International Journal of Innovative Research in Computer

and Communication Engineering

(An ISO 3297: 2007 Certified Organization)

Vol. 2, Issue 6,  June 2014

Design of 4th

Order Parallel Coupled Microstrip

Bandpass Filter at Dual Frequencies of 1.8 GHz

and 2.4 GHz for Wireless Application

S.Srinath

UG Student, Dept. Of ECE, Vellore Institute Of Technology, Vellore, Tamilnadu, India

ABSTRACT: Design of a parallel-coupled microstrip bandpass filter is presented in this paper. The aim of this  paper is to present the design technique, parameter analysis, real prototype fabrication and measurement results at  dual simulation  frequencies of 1.8GHz and 2.4GHz. Half wavelength long resonators and admittance inverters are used to design the filter. The filter is simulated using AWR Microwave Office software (Advanced Wave Research).

KEYWORDS: Bandpass filter; Microstrip; 1.8 GHz & 2.4GHz; Parallel Coupled Line; Microwave Engineering; AWR Simulator.

I.INTRODUCTION

The microwave filter is a two port network which used to control the frequency response by providing transmission at frequencies within the passband and attenuation in the stopband of a filter. Filters are an essential part of telecommunications and radar systems. Of its low-cost fabrication, easy integration and simple designing procedure, the parallel coupled-line/edge-coupled filters are widely used in microwave microstrip circuits with a required bandwidth up to 20 % of central frequency . A bandpass filter only passes the frequencies within a certain desired band and attenuates others signals whose frequencies are either below a lower cutoff frequency or above an upper cut-off frequency. The range of frequencies that a bandpass filter let’s to pass through is referred as passband. A typical bandpass filter can be obtained by combining a low-pass filter and a high-pass filter or applying conventional low pass to bandpass transformation . The architecture demonstrated here is a coupled line type filter, since this is among the most practical and common filter types which can meet the stated specifications. In Coupled Transmission Lines, coupling between two transmission lines is introduced by their proximity to each other. Coupling effects may be undesirable, such as crosstalk in printed circuits, or they may be desirable, as in directional couplers where the objective is to transfer power from one line to the other . Another of their major use is using them in filtering the Microwave range frequencies.

The filter response will be based on the Chebychev transfer function. Chebychev type filters are popular for their high selectivity, i.e., they have a relatively fast signal cut off between pass and stop band. Filters operating in gigaherz frequency ranges rely on distributed transmission line structures to obtain the desired frequency response. Dimensions of the coupled transmission lines can be derived with published formula or minimal simulation software capability.

II.RELATED WORK

This paper presents the design of a parallel-coupled microstrip bandpass. The design is based on the use of half wave long resonators and admittance inverters. The dual center frequencies of 1.8 GHz & 2.4GHz are selected, the bandwidth (BW) is about 5%, the minimum attenuation amounts to -30 dB and the pass-band ripple is obtained equal to 0.5 dB.The design technique, parameter analysis, real prototype fabrication and measurement results of a 4th order coupled line bandpass filter at a dual simulation  frequencies of 1.8GHz & 2.4GHz is presented in this paper.

III. THEORY

A general layout of a parallel coupled microstrip bandpass is shown in figure 3.1 . The filter structure consists of open circuited coupled microstrip lines . These coupled lines are quarter wavelength , (λ/4) long and are equivalent to shunt resonant circuits. The coupling gaps correspond to the admittance inverters in the low-pass prototype circuit. Even- andodd- mode characteristic impedances of parallel-coupled half-wave resonators are computed using admittance inverters. These even- and odd- mode impedances are then used to compute physical dimensions of the filter. Now consider a bandpass filter composed of a cascade of N + 1 coupled line sections, as shown in Figure 3.1. The sections are numbered from left to right, with the load on the right, but the filter can be reversed without affecting the response. Since each coupled line section has an equivalent circuit of the form, the equivalent circuit of the cascade is as shown in Figure 3.2.

IV. IMMITANCE INVERTER

Immittance inverters play a very important role in filter design. They are used to transform a filter circuit into an equivalent form that can be easily implemented using various microwave structures. Immittance inverters are either impedance or admittance inverters. Making use of the properties of immittance inverters, bandpass filters may be realized by series (L-C) resonant circuits separated by impedance inverters (K) or shunt (L-C) parallel resonant circuits separated by admittance inverters (J). To design a bandpass filter, first of all a low-pass prototype circuit is modified to include immittance inverters. These low pass structures are then converted to bandpass circuits by applying conventional low-pass to bandpass transformation.

V.SIMULATION MODELING AND DISCUSSION

The design equations for the coupled line are as follows:

The order of the filter was calculated assuming an equi-ripple (Chebyshev type 1) response with an insertion loss (L) of 30dB at the center frequency of  1.8Ghz and 2.4Ghz and the passband ripple amplitude (G) of 0.5dB. The fractional bandwidth  = 5%. Hence the upper and lower cutoff frequencies of the passband are 2.52 GHz and 2.28 GHz respectively. Using the standard Chebyshev model:

This gives us  = 4. Now, we get the lowpass prototype values from the standard Chebyshev table:

Now, we use the following design equations to get the inverter constants for a coupled line filter with N+ 1 sections:

Now, the even and odd mode impedances can be calculated as follows:

The results of these calculations are tabulated below:

V.SIMULATION DESIGN, RESULTS & DISCUSSION

The design was simulated using AWR Design Environment (9.00.4847) and a response was generated. The coupled line design used for simulation was MCFIL which is a non-floating line. This is a coupled line model with the end effect included for the open ended line. One side of each coupled line is the ground plane.

Figure 5.1 : Layout of the proposed 4th  order filter design in AWR Software

Here, the parameter S_11(dB) represents the insertion loss at port 1 and this parameter which has a value of -6.521dB at the center frequency of 2.4 GHz while -6.587dB at the center frequency of 1.8GHz

The parameter S_21 (dB) represents the insertion loss from port 1 to port 2 which has a value of -2.633dB at the center frequency of 2.4GHz while -6.375dB at the center frequency of 1.8GHz.

Figure 5.2 : Coupled Line Bandpass Filter at Dual Frequencies Result

The first design discussed above was simulated in AWR. The same was simulated using EM simulation. The schematic diagram for the same is given below:

Figure 5.3 : Layout of the proposed 4th  order filter design in AWR Software using EM simulation

Here, the parameter S_11  (dB) represents the insertion loss at port 1 and the parameter which has a value of -2.606dB at the center frequency of 2.4 and 1.8GHz

The parameter S_21 (dB) represents the insertion loss from port 1 to port 2 which has a value of -16.87dB at the center frequency of 2.4GHz while -31.55dB at the center frequency of 1.8GHz.

Figure 5.4 : Coupled Line Bandpass Filter at Dual Frequencies EM Simulation Result

For the Stackup, the dielectric used is FR4 and the conductor is copper. The transmission lines used in the design are MCLIN which are essentially similar to MCFIL lines with their remaining ends left open. The thickness of the dielectric layer is taken as 1.58mm and air thickness is taken as 24mm.

The simulation is done on EMSight with X and Y cell resolution of 0.5mm and an extension of 1mm. The extracted EM schematic is given below:

VI. CONCLUSION

On a substrate with a dielectric constant of 4.4,with the dual center frequencies of 1.8 GHz & 2.4 GHz, a coupled line bandpass filter was simulated with the bandwidth of about 5%, with the minimum attenuation of 30 dB and with the passband ripple equal to 0.5 dB. Thus the design technique, parameter analysis, real prototype fabrication and measurement results at dual simulation frequencies of 1.8GHz and 2.4GHz of a 4th order coupled line bandpass filter was presented in this paper.

VIII. ACKNOWLEDGEMENT

At the outset, I would like to express my gratitude for my institute – Vellore Institute of Technology (V.I.T.) for providing me with the opportunity to undergo my undergraduate training, and assimilate knowledge and experience hitherto unknown to me.

REFERENCES

[1] D. M. Pozar, “Microwave Engineering”, John Wiley & Sons Inc., 1998.

[2] Miguel Bacaicoa, David Benito, Maria J. Garde, Mario Sorolla and Marco Guglielmi, “New Microstrip Wiggly-Line Filters with Spurious Passband Suppression”, IEEE Transactions on microwave theory and techniques, vol. 49, no. 9, September 2001.

[3] John T. Taylor and Qiuting Huang, “CRC Handbook of Electrical Filters”, CRC Press, pp. 22-23, 1997.

[4] “Tuning, Optimization and Statistical Design”, Agilent Technologies, May 2003. R. Levy, S. B. Cohn, “A History of Microwave Filter Research, Design, and Development”, Microwave Theory and Techniques, IEEE Transactions, vol. 32, no. 9, pp. 1055,1067, Sep 1984.

[5] A. Naghar, O. Aghzout, F. Medina, M. Alaydrus, M. Essaidi, “Study and Design of a Compact Parallel Coupled Microstrip BandPass Filter for a 5 GHz Unlicensed Mobile WiMAX Networks,” International Journal of Science and Technology, vol. 2, No. 6, June 2013. Sina Akhtarzard, Thomas R. Rowbotham, and Petter B. Johns, “The Design of Coupled Microstrip Lines”, IEEE Transactions on Microwave Theory and Techniques, vol. MTT-23, no. 6, pp. 486-492, June 1975. E. O. Hammerstard, “Equations for microstrip circuit design,” in Proceedings of the European Microwave Conference, Hamburg, Germany, 1975, pp. 268–272.

[6] Annapurna Das and Sisir K Das, “Microwave Engineering”, MacGraw Hill, p305, 2001.

[7] Hong, J.S., M.J, “Microstrip Filter for RF/Microwave Applications”, A Wiley-Interscience Publication, Canada, 2001.

[8] C. A Balanis, “Antenna Theory: Analysis and Design”, 3rd edition, Wiley, 2005.

[9] S. B. Cohn, “Parallel-Coupled Transmission-Line-Resonator Filters,” Microwave Theory and Techniques, IRE Transactions on , vol. 6, no. 2, pp. 223-231, April 1958.

[10] S. Seghier, N. Benahmed, F. T. Bendimerad, N. Benabdallah, “Design of parallel coupled microstrip bandpass filter for FM Wireless applications”, Sciences of Electronics, Technologies of Information and Telecommunications (SETIT), 6th International Conference , pp.207-211, 21-24 March 2012. A. R Othman, I.M. Ibrahim, M. F. M. Selamat, M. S. A. S. Samingan, A. A. A. Aziz, H. C. Halim, “5.75 GHz microstrip bandpass filter for ISM band”, Applied Electromagnetics, APACE Asia-Pacific Conference on , pp. 1-5, 4-6 Dec. 2007. I. Azad, Md. A. H. Bhuiyan, S. M. Y. Mahbub, “Design and Performance Analysis of 2.45 GHz Microwave Bandpass Filter with Reduced Harmonics”, International Journal of Engineering Research and Development, vol. 5, no. 11, pp. 57-67, 2013.

[11] John T. Taylor and Qiuting Huang, “CRC Handbook of Electrical Filters”, CRC Press, pp. 22-23, 1997.

BIOGRAPHY

Design and Real Prototype Fabrication Of a Free

Space Optical Transmitter and Receiver

S.Srinath

UG Student, ECE, Vellore Institute of Technology, Vellore, India

Abstract: We are communicating with each others for every purpose. Different modes of communication are used. Free space optics is one of the mode of communication. Free space optics is widely used by satellites for transmitting with each other. Design and real prototype fabrication of a low cost portable free space optical transmitter and receiver is presented in this paper. Using this prototype wireless communication is possible. Light from a laser torch is used as the carrier in the circuit. The laser torch can transmit light up to a distance of about 500 meters. The transmitter circuit comprises of condenser microphone transistor amplifier BC548. The gain of the op-amp can be controlled with the help of 1-mega-ohm potmeter. The transmitter uses 9V power supply. The receiver circuit uses an npn phototransistor as the light sensor that is followed by a two-stage transistor preamplifier and LM386-based audio Power amplifier. This paper deals with the designing of a very low cost free space optical system which is perfect for information transmission of general conversation, using an ordinary available Laser torch of cost. The circuit is designed using National Instrumentations Multisim11.0 (N.I. Multisim 11.0) and National Instrumentations UltiBoard11.0 (N.I. UltiBoard 11.0).

Keywords: Battery driven design, Free space optics, Laser torch, Low cost design, N.I. Multisim and N.I. UltiBoard Simulator, Voice or data transmission.

Low Pass Filter Design Comparison Using

Agilent Genesys

S.Srinath

Student, ECE, Vellore Institute of Technology, Vellore, India

Abstract: Wireless communication is becoming more and more popular. In this paper, a maximally flat lowpass filter and a equal-ripple lowpass filter have been designed for Ultra High Frequency (UHF) band ie I.T.U. band 9 (Frequency 300Mhz – 3000Mhz; Wavelength 1m – 100mm).Application of UHF band includes television, microwave ovens, mobile phones, wireless LAN, Bluetooth, etc. The filters are designed from the method of "Impedance and Frequency Scaling". The design parameters and return loss are discussed. Also the amplitude (attenuation in dB) vs frequency graph is obtained for both the filters and their results are compared and suitable conclusions are drawn. The filters are designed using Agilent Genesys 2010.05

Keywords: Agilent Genesys Simulator; Low Pass Filter; Equal-ripple filter; Smith chart; Polar Chart; Maximally flat filter; Wireless communication; UHF Band Spectrum; S Parameters.

Optisystem based CATV System-Performance

Improvement by Using External Light-

Injection Technique

S.Adithyan^1, S.Srinath^2

U.G. Student, Department of EEE, C. Abdul Hakeem College of Engineering & Technology, Vellore, Tamilnadu, India^1

Final Year Student, B.Tech, Department of ECE, Vellore Institute of Technology, Vellore, Tamilnadu, India^2

ABSTRACT: Cable Television (CATV) is designed with erbium-doped amplifier-repeated system that uses an external light – injection technique and a directly modulated wave using amplitude modulation. The external light – injection technique can greatly enhance the frequency response of the laser diode, and hence improve the overall performance of the fibre optical CATV system. It implemented using Optiwave Optisystem 10.0.

KEYWORDS: External Light–Injection Technique, Semiconductor Lasers, Optical Communication, Directly Modulated Transmitter.

I.INTRODUCTION

CATV is a shared cable system that uses a tree-and-branch topology in which multiple households within a neighborhood share the same cable. Cable television is a system of distributing television programs to subscribers via radio frequency (RF) signals transmitted through coaxial cables or light pulses through fiber-optic cables. The abbreviation CATV is often used for cable television. It originally stood for Community Access Television or Community Antenna Television, from cable television's origins in 1948, in areas where over-the-air reception was limited by distance from transmitters or mountainous terrain, large "community antennas" were constructed, and cable was run from them to individual homes.

II. RELATED WORK

Lu et al [7] developed a CATV system Based on Lower-Frequency Sidemode Injection-Locked Technique with an injection power level of 4.8 dBm.

Wen et al [8] proved that Injection-locking enhances the resonance frequency of the laser and the electrical feedback achieves strong resonance at the base-rate frequency of the injected data streams.

Our paper is based on directly modulated transport system which employs the external light-injection technique. The external light-injection technique greatly enhances the frequency response of the laser diode, and thus improves the overall performance of the fibre optical CATV system. The idea is implemented using Optisystem 10.0 and we analyse how the output power varies with and without the external light-injection technique. Using external light-injection technique we are analysing how the output power varies with 3dBm, 4dBm, 5 dBm and 8 dBm external injected power.

III. INTODUCTION TO THE EXTERNAL-LIGHT INJECTION TECHNIQUE

The recent changes in telecommunication regulations and changing market forces are making the market for broadband network services to the home an extremely lucrative and competitive area. Out of many competing technologies for such broadband services, major CATV companies are banking heavily on various methods of making the network more and more fast and efficient. Most of the interest exists in broadband network services to deliver a variety of products to consumers, such as Internet access, telephony, interactive TV, and video on demand. But due to its cost efficiency, we need to find a better way to do that. When we send any optical signal, we find there is some loss in the transmission and hence there is the loss in data. So to increase the fibre transmission distance, achieve high quality for the given system and increase the performance is the ultimate goal of the fibre optical cable television (CATV) transport systems. However, nonlinear distortions introduced by laser chirp, fibre dispersion effects can degrade the system performance as well as limit the maximum transmission distance. Till now many techniques have been devised to circumvent these problems, but many of them just increase the complexity of the system. In a recent study, external light-injection technique has been employed in a hybrid radio–fibre system to improve the bit-error-rate performance but it has not been employed as a system-performance improvement technique in an analog light wave system. We suggest that the external light injection technique can be used to meet all the goals of CATV system efficiently. The external light-injection technique can greatly enhance the frequency response of the laser diode. It is expected to have good performances in analog fibre optical CATV systems.

IV. THE CATV NETWORK

A CATV network is made up of three main parts: the trunk, the feeder, and the customer drop. The trunk is usually intended to cover large distances of tens of miles. The feeder portion of the cable is used by the consumers for tapping signal. Its maximum length is only a few miles since energy is tapped off to feed homes (subscribers) which require relatively high power levels. The drop is the flexible cable which goes to the home and it has a maximum length of approximately 600 feet and is made up of lower quality coaxial cable than the feeder or trunk. Older generation CATV systems used coaxial cables in the trunk and feeder portions of the network and therefore experienced many problems related to (a) interference from spurious radiation, (b) distortions introduced by amplifiers and (c) limited bandwidth. Long-distance transmission of fibre AM-VSB 80-channel CATV systems is used widely and is spread throughout the cable industry. Whereas, the maximum transmission distance of such systems is still limited by RF parameters and it is difficult to obtain better CNR performance due to full channel loading. In an optical CATV system, the signal is directly or externally modulated with light wave before it communicates. Directly modulating signal with LD is an economic method whereas the transmission distance and performance are significantly limited by laser chirping issues. In order to provide an economic structure with advanced transmission performance in external modulation system, direct modulation method is often combined with other techniques or components to compose higher performance and lower cost CATV system. By increasing the wavelength numbers, major parts of CSO distortions from each communication band are automatically removed from each communication channel. External light technique in particular have been experimented and proved as efficient method to enhance laser output power and laser resonance frequency.

V. SIMULATION DESIGN

Our proposed directly modulated transport system employs the external light-injection technique. Without external light injection (Fig 3), CH 2-40 (ranging from 55 – 320 MHz) are directly fed into the first Continuous Wave (CW) laser diode and CH 41-78 (325 – 550 MHz) are directly fed into the second one. The CATV frequency bands are up-converted to the first microwave frequency bands (14.75 – 15.25 GHz) and then fed into the Continuous Wave (CW) laser diodes. The second CATV frequency bands are up-converted to the second microwave frequency bands (18.25 – 18.75 GHz) and then fed into the CW laser diodes. The central wavelengths of the two CW laser diodes are 1550.5nm and 1555.7nm, respectively. Without external light injection, the relative intensity noise (RIN) of the two CW laser diodes is about -170 dB/Hz. With external light injection, the RIN of the two DFB laser diodes are lower than -170 dB/Hz. Light is injected in the counter propagation direction through an optical isolator and a 3-dB optical coupler. The wavelengths of the injected light are 1550.7nm and 1555.6nm, respectively. In the system the optical power was coupled into the EDFA - I by a 2x1 optical coupler. After a 50 km single-mode fibre (SMF) transmission, the received optical signal was split by a 1x2 optical splitter, went through two separate optical band pass filters in order to select the appropriate wavelength, and detected using two broadband analog optical receivers. This system can be used to increase the power of the sent signal to a larger extent while maintaining the efficiency at the same time.

VI. SIMULATION, RESULT AND DISCUSSION

When the power injected into the laser diode is increased, the power launched into the EDFA-I is also increased. This is due to the fact that the external light injection will reduce the laser diode threshold current and hence increase the optical output power of the laser diode. The higher the input power launched into the EDFA, the better the CNR performance we can obtain in the system.

In the normal case (without light injection) by using the 30dBm source light the electrical power output of the system is 2.34dBm . By using the 3dBm, 4dBm, 5 dBm and 8 dBm external light injection technique the electrical power output is 4.45dBm, 5.21dBm, 6.53 dBm and 8.34 dBm respectively.

A plot of "Injected Power" vs "Output Power" is shown below. This plot concludes that as injected power through the external light injection technique is increased then the output power also increases.

The output power as seen through a "Electrical Power Meter Visualizer" for a CATV system without external light injection is shown below.

The output power as seen through a "Electrical Power Meter Visualizer" for a CATV system employing external light injection (3dBm injection) is shown below.

The output power as seen through a "Electrical Power Meter Visualizer" for a CATV system employing external light injection (4dBm injection) is shown below.

The output power as seen through a "Electrical Power Meter Visualizer" for a CATV system employing external light injection (5dBm injection) is shown below.

The output power as seen through a "Electrical Power Meter Visualizer" for a CATV system employing external light injection (8dBm injection) is shown below.

VII. CONCLUSION

We propose and demonstrate a directly modulated AM-CATV EDFA-repeated system that uses the external light-injection technique to improve the systems" performance. The external light-injection technique greatly enhances the frequency response of the laser diode, and thus improves the overall performance of the fibre optical CATV system. The efficiency of the CATV system can be further increased by feeding the customers using the optical fibre i.e. fibre to home in place of coaxial cable. This can increase the efficiency by 10 times as compared to normal coaxial cable.

REFERENCES

[1] D. Piehler, C. Y. Kuo, J. Kleefeld, and C. Gall, “Nonlinear intermodulation distortion in an optically amplified analog video transport system with dispersion compensation fiber,” in Eur. Conf. Opt. Communications, Paper WeP.02, pp. 3217–3220, 1996.

[2] J. Helms, “Intermodulation and harmonic distortions of laser diodes with optical feedback,” J. Lightwave Technol., vol. 9, pp. 1567–1575, Nov.1991.

[3] S. H. Lee, J. M. Kang, I. H. Choi, and S. K. Han, “Linearization of DFB laser diode by external light-injected cross-gain modulation for radio-over-fiber link,” IEEE Photon. Technol. Lett., vol. 18, no. 14, pp. 1545–1547, Jul. 15, 2006.

[4] Y. Hong and K. A. Shore, “Locking characteristics of a side-mode injected semiconductor laser,” IEEE J. Quantum Electron., vol. 35, no. 11, pp. 1713–1717, Nov. 1999.

[5] S. K. Mondal, B. Roycroft, P. Lambkin, F. Peters, B. Corbett, P. Townsend, and A. Ellis, “A multiwavelength low-power wavelength-locked slotted Fabry–Pérot laser source forWDMapplications,” IEEE Photon. Technol. Lett., vol. 19, no. 10, pp. 744–746, May 15, 2007.

[6] X. J. Meng, T. Chau, and M. C. Wu, “Experimental demonstration ofmodulation bandwidth enhancement in distributed feedback lasers with external light injection,” Electron. Lett., vol. 34, pp. 2031–2032, 1998.

[7] Lu, H.-H., Patra, A. S., Tzeng, S.-J., Peng, H.-C., and Lin, W.-I., “ Improvement of Fiber-Optical CATV Transport Systems Performance Based on Lower-Frequency Sidemode Injection-Locked Technique.”, IEEE Photonics Technology Letters 20, 351-353, 2008.

[8] Attygalle, M., and Wen, Y. J. ,“Injection-locked Fabry-Perot laser with electronic feedback for clock recovery from high-speed OTDM signals.” IEEE Photonics Technology Letters 18, pp. 478-480, 2006.

[9] Choi, K. M., Baik, J. S., and Lee, C. H. ,“ Broadband light source using mutually injected Fabry-Perot laser diodes for WDM-PON.”, IEEE Photonics Technology Letters 17,pp. 2529-2531, 2005.

[10] Hann, S., Kim, D. H., and S., P. C. ,“ Uni-lambda bidirectional 10/1.25 GbE access service based on WDM-PON.”, Electronics Letters 40, pp.194-195, 2004.

[11] Ni, Y., Zhang, L., An, L., Peng, J., and Fan, C., “ Dual-core photonic crystal fiber for dispersion compensation.”, IEEE Photonics Technology Letters 16, pp. 1516-1518, 2004.

[12] Lu, H.-H., Huang, H.-H., Su, H.-S., and Wang, M.-C., “ Fiber Optical CATV System-Performance Improvement by Using External Light-Injection Technique.” , IEEEPhotonics Technology Letters 15,pp. 1017-1019, 2003.

[13] Kaszubowska, P. Anandarajah, and L. P. Barry, “Improved performance of a hybrid radio/fiber system using a directly modulated laser transmitter with external injection,” IEEE Photon. Technol. Lett., vol.14, pp. 233–235, Feb. 2002.

[14] H. H. Lu, C. T. Lee, and C. J. Wang, “Dispersion compensation in externally modulated transport system using chirped fiber grating as well as large effective area fiber,” Opt. Eng., vol. 40, pp. 656–657, 2001.

[15] Srinath, S. "Performance Analysis of 2.5 Gbps GPON.", International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering , Vol.3 , Issue.6, pp:10148-10155, June,2014,.

[16] L. P. Shen, W. P. Huang, G. X. Chen, and S. S. Jian, "Design and optimization of photonic crystal fibers for broadband dispersion compensation," IEEE Photon. Technol. Lett., vol. 15, pp. 540-542, 2003.

[17] Y. J. Wen, C.-J. Chae, and H. F. Liu, “Time-domain polarization interleaving of signal to allow polarization-insensitive all-optical clock recovery,” IEEE Photon. Technol. Lett., vol. 17, no. 6, pp. 1304–1306, Jun. 2005.

[18] H. H. Lu, C. L. Ying, W. I. Lin, Y. W. Chuang, Y. C. Chi, and S. J. Tzeng, “CATV/ROF transport systems based on light injection/optoelectronic feedback techniques and photonic crystal fiber,” Opt. Commun., vol. 273, pp. 389–393, 2007.

[19] J. L. Thomas, “Cable Television Proof-Of-Performances,” in Hewlett-Packard Professional Book, ch. 8, pp. 158–193,1998.

[20] S. Kawanishi, “High bit rate transmission over 1 Tbit/s,” IEICE Trans. Commun., vol. E84-B, no. 5, pp. 1135–1141, 2001.

BIOGRAPHY

Performance Analysis of 2.5 Gbps GPON

S.Srinath

B.Tech , Department of ECE, Vellore Institute Of Technology, Vellore, Tamilnadu, India

ABSTRACT: The ITU-T G.984 is Gigabit-capable Passive Optical Networks (GPON) standard. In this paper, 2.5 Gb/s GPON link is presented. The quality or performance of a digital communication system is specified by its BER or Q value with respect to other parameters such as receiver sensitivity . The system performance is presented through various parameters such as Q factor, eye diagram. The proposed models have the nominal bit rate 2.5 Gbit/s with required bandwidth. It implemented using OptiSystem 7.0.

KEYWORDS: GPON, Bit Error Rate(BER), Q Factor, Eye Diagram.

I. INTRODUCTION

Fiber optics uses light signals to transmit data. As this data moves across a fiber, there needs to be a way to separate it so that it gets to the proper destination. A passive optical network does not include electrically powered switching equipment and instead uses optical splitters to separate and collect optical signals as they move through the network. A passive optical network shares fiber optic strands for portions of the network. Powered equipment is required only at the source and receiving ends of the signal. GPON (Gigabit Passive Optical Network) network consists of three important units ie Optical Line Terminal (OLT), Optical Network Unit (ONU) and Optical Splitters. The data is transmitted from the central office to a single optical fibre which runs from the central office to the optical splitters. This splitter then divides the power into N separate paths that goes to different subscribers. The number of splitting paths can vary from 2 to 64.Optical Line Terminal is a device that serves as the service provider endpoint of a passive optical network. It has two main functions: To perform conversion between the electrical signals used by the service provider’s equipment and the fiber optic signals used by the passive optical network. To coordinate the multiplexing between the conversion devices on the other end of that network (called Optical Network Units).Optical Network Unit is used in combination with an Optical Line Terminal (OLT). It is a device that terminates any one of the endpoints of a fiber to the premises network. It transforms incoming optical signals into electronics at a customer's premises. Optical Splitters are used to divide the incoming light beam from a single fiber into two or more fiber channels.GPON offers many advantages:It supports triple play service. It is a term for the provisioning of two bandwidth intensive service-high speed internet access and television and a less bandwidth demanding service, telephone over a single broadband connection.It has a high bandwidth transmission and long reach service coverage (20 km).Since PON uses the same fiber for upstream as well as downstream transmission, it utilizes WDM (Wave Division Multiplexing) for bidirectional transmission. It adopts two multiplexing techniques. In the downstream direction the data packets are transmitted in a broadcast manner. 1,490 nm wavelength is used for downstream traffic while in the upstream direction the packets are transmitted in a TDMA manner. The wavelength used for upstream traffic is 1310 nm. 1550 nm is reserved for overlay services, typically RF video (analog).

In this paper different characteristics like jitter, minimum Bit Error Rate (BER), Q factor and optical power for different wavelengths are compared. We will also see the variation of these factors when there is a change in the fiber attenuation.

II. RELATED WORK

While previous survey and research papers focussed on the downstream performance of a GPON system for data rates less than 2Gbps, this paper focuses on both the upstream and downstream performance of a GPON for data rate above 2Gbps ie 2.5Gbps(ITU-T G.984.1 standard).Higher data rate simulation is performed in this paper as high speed GPON network are the need of the hour. The performance measure of a GPON system presented in this paper analyses how the BER , Q-Factor and Optical power changes as wavelength and attenuation changes and how effective these factors are for better communication. The downstream performance analysis of GPON system is analysed for ‘single user’ case and ‘multiple user’ case. The upstream performance analysis of GPON system is analysed for ‘multiple user’ case. For analysing the performance of multiple user GPON system ‘BiDirectional Optical Fibres’, ‘BiDirectional Circulators’ and ‘BiDirectional Splitters’ available in Optisystem 7.0 software were used.

III. THEORY

Bit Error Rate (BER) is defined as the number of bit errors is the number of received bits of a data stream over a communication channel that has been altered due to noise, interference, and distortion or bit synchronization errors. BER is the number of bit errors divided by the total number of transferred bits during a studied time interval ie ( ) where E(t) is the number of bits received in error over time t, and N(t) is the total number of bits ( ) transmitted in time t. BER is a unit less performance measure, often expressed as a percentage.Q Factor describes how under damped an oscillator or resonator is. Higher Q factor indicates a lower loss of energy.Higher Q indicates a lower rate of energy loss relative to the stored energy of the resonator. A high-Q tuned circuit in a radio receiver would have more selectivity and hence better job of filtering out signals from other stations that lie nearby on the spectrum.Eye Diagram patterns are a widely used tool for studying the quality and stability of optical communication systems. The quality of the signals can be judged from the appearance of the eye. It is an experimental tool for the evaluation of the combined effects of channel noise and inter symbol interference on the performance of a baseband pulse-transmission system. It is the synchronized superposition of all possible realizations of the signal of interest viewed within a particular signaling interval. It is a composite view of all the bit periods of a captured waveform superimposed upon each other. If the bottom appears to have a smaller amplitude variation than the top, the signal seems to carry more 0s than 1s.

The following can be obtained from an eye diagram.

IV. OVERVIEW OF GPON SYSTEM

Recommendation ITU-T G.984.1 describes a flexible optical fibre access network capable of supporting the bandwidth requirements of business and residential services and covers systems with nominal line rates of 2.4 Gbit/s in the downstream direction and 1.2 Gbit/s and 2.4 Gbit/s in the upstream direction. Both symmetrical and asymmetrical (upstream/downstream) gigabit-capable passive optical network (GPON) systems are described.GPON standard defines a lot of different line transmission rates for downstream and upstream direction.

The simulation was performed for a bit rate of 2.5Gbps.

V. SIMULATION DESIGN, MODELING & RESULTS AND DISCUSSION

The proposed 2.5 Gbps simulation model of GPON was done in optisystem software.The model was designed for a ‘single user’ scenario and a ‘multiple user’ scenario. It consist of pseudo random sequence generator, NRZ pulse generator, continuous wave laser source, Mach-Zehender modulator, It also has an ONT receiver should have photodiode, low pass filter,3R generator, BER analyzer, Bessel optical fiber filter. The link, sometimes called channel, is consists of 20 km/50km of single mode fiber SMF28 and optical attenuator so as to add the loss for all the ODN class.

SINGLE USER :

CASE 1:

In CASE 1 , the wavelength of 1490 nm was chosen with a fibre length of 50km and fibre attenuation of 0.7db/km.

In figure 5.1 an open eye pattern is obtained which indicates less jitter and signal distortion. Figure 5.2 represents the Q factor which is high and its sharp graph indicates low loss. Figure 5.3 indicates the BER which is less. The optical power at the end of the fiber through which the signal has been transmitted has reduced from 6.75 dBm to -29.418 dBm.

CASE 2:

In CASE 2 , the wavelength of 1699.983 nm was chosen with a fibre length of 50km and fibre attenuation of 0.6db/km.

Table.5.2. Results

Figure 5.4 has more number of amplitude variation at the one level than the zero level. Hence there are more number of one’s in the signal than zero’s. Figure 5.5 represents the Q factor which is around 20. Figure 5.6 indicates the BER which is low. The optical power at the end of the fiber through which the signal has been transmitted has reduced from 6.785 dBm to -24.501 dBm.

CASE 3:

In CASE 3 , the wavelength of 1700 nm was chosen with a fibre length of 50km and fibre attenuation of 0.2db/km.

Table.5.3. Results

In figure 5.7 the eye opening is very small indicating lot of noise and crosstalk in the signal. Figure 5.8 represents the Q factor which is low. Figure 5.9 indicates the BER which too has increased from the previous cases. The optical power at the end of the fiber through which the signal has been transmitted has reduced from 6.785 dBm to -5.473 dBm.

The wavelength of 1550 nm was chosen with a fibre length of 20km and fibre attenuation of 0.2db/km.

In figure 5.11 an open eye pattern is obtained which indicates less jitter and signal distortion. Figure 5.12 represents the Q factor which is high and its sharp graph indicates low loss. Figure 5.13 indicates the BER is less. The optical power at the end of the fiber through which the signal has been transmitted has reduced from -6.172 dBm to -13.172 dBm.

VI. CONCLUSION

SINGLE USER - From the graphs we can see that as the wavelength is changed from 1490 nm to 1700 nm the eye diagram changes. In the first case i.e. 1490 nm an open eye pattern is obtained which indicates less jitter and signal distortion. The Q factor is high and its sharp graph indicates low loss. Also the BER is less. The optical power at the end of the fiber through which the signal has been transmitted has reduced from 6.75 dBm to -29.418 dBm.

The second case 1699.983 nm has more number of amplitude variation at the one level than the zero level. Hence there are more number of one’s in the signal than zero’s. The jitter has increased from the previous cases. The Q factor has reduced to a mere 20 and there is a small BER too.

In the third case of 1700 nm, the eye opening is very small indicating lot of noise and crosstalk in the signal. There is a huge amount of jitter and it has a very low Q factor. The BER too has increased from the previous cases. Thus performance of the network is best obtained at a wavelength of 1490 nm.

MULTIPLE USER USING BIDIRECTIONAL LINK - From table 5.4,the wavelength was chosen to be 1550 nm in which Q factor was found out to be around 6 for the ‘Optical network units’ and the BER was found out to be 10^-12. Similarly for the uplink Q factor was found out to be around 6 for the ‘OLT’ and the BER was found out to be 10^-8. Thus, we see that the Q factor and the BER was exceptionally good for the GPON system operating at a wavelength of 1550nm and an input power of 10dbm using an optical fibre of length 20km with an attenuation of 0.2db/km.

VIII. ACKNOWLEDGEMENT

At the outset, I would like to express my gratitude for my institute – Vellore Institute of Technology (V.I.T.) for providing me with the opportunity to undergo my undergraduate training, and assimilate knowledge and experience hitherto unknown to me. I would like to sincerely thank my teacher, Prof. Revathi.S -  Assistant Professor(Selection Grade), for her constant support during the course of my activities. I will forever be obliged to madam for her assistance, encouragement and guidance.

REFERENCES

[1] X. Z. Qiu, J. Vandewege, F. Fredricx, and P. Vetter, “Burst Mode Transmission in PON Access Systems”, 7th Eur. Conf. networks Optical Communication, pp.127–132,2002.

[2] Xing-Zhi Qiu,“Development of GPON Upstream Physical-Media-Dependent Prototypes,” Journal of Lightwave Technology,Vol.22, Issue.11, pp.2498 – 2508,2004.

[3] P. Vetter ,“Study and Demonstration of Extensions to the Standard FSAN BPON” ,Int. Symp. Services Local Access,pp.119–128, 2002.

[4] ITU-T recommendation G.984.1, “Gigabit-capable Passive Optical Networks (GPON): General Characteristics”, International Telecommunication Union, March 2003.

[5] ITU-T Recommendation G.984.2, “Gigabit-capable Passive Optical Networks (G-PON): Physical Media Dependent (PMD) layer specification”, International Telecommunication Union, March 2003.

[6] ITU-T Recommendation G.975, “Forward error correction for Submarine systems”, International Telecommunication Union, Oct. 2000.

[7] ITU-T recommendation G.984.4, “Gigabit-capable Passive Optical Networks (GPON): ONT management and control interface specification”, International Telecommunication Union, June 2004.

[8] Bakarman H.A. ,Shaari . S, Ismail.M , “Simulation of 1.25 Gb/s downstream transmission performance of GPON-FTTx”, International Conference on Photonics (ICP), pp. 1 – 5, 2010

[9] V. Alwayn, “Optical Network Design and Implementation”, Cisco Press,2004.

[10] J. H. Franze and V. K. Jain, “Optical Communications: Components and Systems”, Narosa Publishing House, 2000.

[11] T. Antony and A. Gumaste,“WDM Network Design”, Cisco Press, ch. 4,2003.

[12] Lallukka, Sami & Raatikainen,“Pertti. Passive Optical Networks. Transport concepts”, Espoo,2006.

[13] F. J. Effenberger and E. Shraga,“Status of GPON and B-PON standards”, Flexlight-networks,2004.

BIOGRAPHY

Design and Electromagnetic Modeling of E-Plane Sectoral Horn Antenna For Ultra Wide Band Applications On WR-137 & WR-62 Waveguides

S.Srinath

(Final Year Student,ECE, Vellore Institute of Technology, Vellore, India)

ABSTRACT : The Design and EM modeling of a E-Plane Sectoral Horn Antenna for Ultra Wide Band Application on WR-137 and WR-62 standard waveguides are presented in this paper. In E-plane sectoral antenna, the E-Plane is much narrower as the flaring and dimensions of the horn are much greater in that direction. The horn flare angle, horn size, wall thickness, etc of the E-plane sectored horn antenna are examined. The return loss, input impedance, total gain and field pattern of the E-plane sectored horn antenna are observed. The antenna is simulated using ANSOFT HFSS 14.0.

KEYWORDS : Ansoft HFSS Simulator, Beam width, Directivity, E-Plane Horn Antenna, Electromagnetic modeling, Radiation Pattern, Return Loss

I. INTRODUCTION

An antenna is an electrical device which converts electric currents into radio waves, and vice versa. To transmit the signal a transmitter applies an oscillating radio frequency electric signal to the antenna’s terminals, and the antenna radiates the energy in the form of electromagnetic waves.Horn antennas are used as antennas at UHF and microwave frequencies, above 300 MHz. They are used as feeders for larger antenna structures such as parabolic antennas.  Over the hundred years, horn antennas have given the best directive and high power operation for Microwave Frequencies. Design Simplicity and large gain with best matching properties are added advantage of Horn antenna. Applications include Radar, Satellite tracking, Radio astronomy and Communication dish antennas. Other applications are Reflector feeds, Gain standards for antenna measurements, EMC/EMI tests, Communication systems, Direction finding (DF), mm-wave systems.

Fig 1 : A Practical Horn Antenna

A E-plane sectoral horn is one in which the opening is flared in the direction of the E-field.

Fig 2 : E-Sectored Horn Antenna

The E-Plane sectored horn antennas are chosen because of their directional radiation pattern, ability to achieve high gain and directivity, and their ease of fabrication. The horn antenna which is designed was subject to the following constraints:

- Operating frequency around 8 GHz (C Band) for first case and 16 GHz (Ku Band) for second case.

- Maintain a gain of 10 dB over the entire operating frequency range

II. ANTENNA DESIGN

The C and Ku frequency bands were selected as the operating frequency. These bands are selected as they pertain to the communication frequency bands. The design was performed to accomplish an ultrawide bandwidth. (i) For the first case of 8Ghz (C Band) the operating frequency was chosen to be 8Ghz. The waveguide dimensions are a = 34.85mm, b = 15.8mm, waveguide length = 31.75mm. These indicate the standard WR-137 waveguide. Horn size dimensions are b=44.45mm, horn flare length = 95.25mm, wall thickness = 1.626mm. (ii) For the second case of 16Ghz (Ku Band) the operating frequency was chosen to be 16Ghz. The waveguide dimensions are a = 15.8mm, b = 7.9mm, waveguide length = 15.88mm. These indicate the standard WR-62 waveguide. Horn size dimensions are b=22.23mm, horn flare length = 47.63mm, wall thickness = 1.016mm. For both the cases the outer boundary condition is Radiation Boundary Condition. The Radiation Boundary Condition are as follows :

- Absorption achieved via 2nd order radiation boundary

- Place at least λ/4 from strongly radiating structure

- Place at least λ/10 from weakly radiating structure

- The radiation boundary will reflect varying amounts of energy depending on the incidence angle. The best performance is achieved at normal incidence. Avoid angles greater then ~30degrees. In addition, the radiation boundary must remain convex relative to the wave

In HFSS to properly model the far field behavior of an antenna, an appropriate volume of air must be included in the simulation. Truncation of the solution space is performed by including a radiation boundary condition on the faces of this air volume that mimics free space. The appropriate distance between strongly radiating structures and the nearest face of the air volume depends upon whether a radiation boundary condition is used. HFSS also uses Finite Element Method (FEM) as analysis & solution to Electromagnetic problems by developing technologies such as tangential vector finite elements, adaptive meshing, and Adaptive Lanczos-Pade Sweep (ALPS).

Fig 3 : Structure of the proposed E-Plane Horn Antenna

III. PROPOSED MODEL IN ANSOFT HFSS 14.0 FOR CASE 1

The 3D view of the designed E-Plane Horn Antenna in HFSS for a solution frequency of 8Ghz (C-Band ) is shown below. The boundaries for the air-box are set as an ideal propagation space and and the ground plane as perfect electric conductor.

Fig 4 : 3D View of the E-Plane Horn antenna in HFSS for a solution frequency of 8Ghz

Fig 5 : Figure showing the direction of excitation for a solution frequency of 8Ghz

IV. RESULTS AND DISCUSSION FOR CASE 1

The parameters which verify the success of antenna design are beam width, impedance matching , etc. These are analysed here. The gain of the antenna versus frequency with return loss is -44dB at 8Ghz is shown below.

Fig 6 : Return loss in db over frequency range for a solution frequency of 8Ghz

The Radiation pattern for the antenna design in 3D is shown in below.

Fig 7 : 3D Radiation pattern of the antenna in HFSS for a solution frequency of 8Ghz

The 2D plot is total gain for phi = ‘0 deg’ and phi = ’90 deg’ is shown below.

Fig 8 : 2D Plot for total gain versus theta (deg) with phi for a solution frequency of 8Ghz

V.  PROPOSED MODEL IN ANSOFT HFSS 14.0 FOR CASE 2

The 3D view of the designed E-Plane Horn Antenna in HFSS for a solution frequency of 16Ghz (Ku-Band ) is shown below.

Fig 9 : 3D View of the E-Plane Horn antenna in HFSS for a solution frequency of 16Ghz

Fig 10 : Figure showing the direction of excitation for a solution frequency of 16Ghz

VI. RESULTS AND DISCUSSION FOR CASE 2

The parameters which verify the success of antenna design are beam width, impedance matching , etc. These are analysed here. The gain of the antenna versus frequency with return loss is -49dB at around 16 Ghz is shown below.

Fig 11 : Return loss in db over frequency range for a solution frequency of 16Ghz

Fig 12 : The range of input impedance is shown below for a solution frequency of 16Ghz

Fig 13 : 3D Radiation pattern of the antenna in HFSS for a solution frequency of 16Ghz

Fig 14 : 2D Plot for total gain versus theta (deg) with phi for a solution frequency of 16Ghz

VII. CONCLUSION

An Ultra Wide Band E-Plane sectored Horn Antenna operating at solution frequencies of 8Ghz and 16Ghz frequency range was designed. The horn antenna which was designed satisfied the following constraints: (i)Operating frequency around 8 GHz (C Band) for first case and 16 GHz (Ku Band) for second case; (ii)Maintain a gain of 10 dB over the entire operating frequency range. The return loss for both the cases was found to be greater than -40db.Thus the desired results are achieved and the simulated structures are suitable for various applications.

VIII. ACKNOWLEDGEMENTS

At the outset, I would like to express my gratitude for my institute – Vellore Institute of Technology (V.I.T.) for providing me with the opportunity to undergo my undergraduate training, and assimilate knowledge and experience hitherto unknown to me.

REFERENCES

[1] Lei Yang, Weihua Tan, Zhongxiang Shen, and Wen Wu, WideBand Wide-Coverage Linear Array of Four Semi-Circular Sector Horns, IEEE transactions on antennas and propagation, vol. 60, no.8, August 2012.

[2] Thomas A Milligan, Modem Antenna Design (John Wiley & Sons INC, Second Edition.)

[3] Constantine. A. Balanis, Antenna Theory Analysis & Design (John Wiley, & Sons INC, Third Edition.)

[4] M. M. Tentzeris, J. Laskar, J. Papapolymerou, S. Pinel, V. Palazzari, R. Li, G. DeJean, N. Papageorgiou, D. Thompson, R.Bairavasubramanian, S. Sarkar, and J.-H. Lee, 3D Integrated RF and millimeter-wave functions and modules using liquid crystal polymer (LCP) system-on-package technology, IEEE Trans. Adv. Packag., vol. 27, no. 2, pp. 332–340, May 2004.

[5] D. M. Pozar and D. H. Schubert, Microstrip Antennas—The Analysis and Design of MicrostripAntennas and Arrays (New York: IEEE Press, 1995.)

[6] F.Mohamadi Monavar , N.Komjani and P.Mousavi, Application of Invasive Weed Optimization to design a broadband Patch antenna with symmetric radiation Pattern, IEEE antennas and wireless propagation letters,Vol.10,2011.

[7] Qi wu ,ronghong jin, and junping geng, A Single layer ultrawideband microstrip antenna , IEEE antennas and wireless propagation letters,vol.1,January 2010.

[8] A. W. Love , Antenna Engineering Hand book (R. C. Johnson and H. Jasik, Ed. New York, 1984.)

BIOGRAPHY

S.SRINATH passed 10th  C.B.S.E. Board with a mark of 475/500(95%) and 12th C.B.S.E. Board from D.A.V. Boys Senior Secondary School, Gopalpuram, Chennai ,India with a mark of 458/500(91.6%).Currently he is studying final year B.Tech, ECE, School of Electronics Engineering in Vellore Institute of Technology , Vellore, India.

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