IOSR Journal of Electronics and Communication Engineering (IOSR-JECE) e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 12, Issue 1, Ver. I (Jan.-Feb. 2017), PP 14-23 www.iosrjournals.org DOI: 10.9790/2834-1201011423 www.iosrjournals.org 14 | Page An Novel Ultra Broad-Band Exponential Taper Transmission Line 8- Port Network 1, Adnan Affandi, 2, Abdullah Dobaie, 3, Yasser Gharbi 1,2,3 Electrical and Computer Engineering Department King Abdul Aziz University Abstract: An novel Ultra Broad-Band Exponential Taper Transmission Line 8- Port Networkis analyzed. The parameters of this developed network is calculated and its frequency responses are computed. Comparison between the simulated and measured parameters are presented. Keywords: Exponential Taper; 8-Port network; Nonuniform Taper I. Introduction Because of the great applications of the eight- port networks in microstrip line and microwave field, intensive work, research and effort have been conducted and devoted in order to improve thier performances and quality. For instance G. P. Riblet [1] has proposed a symmetrical eight-port ring composed of microstrip lines and slot lines on the face and back of the provided substrate. This proposed network found an important application as a phase comparator circuit in monopoles radar in order to control both the azimuth and the elevation of the target. While I, Ohta, T. Kawal, S. Shimahashi and K. Ho. [2] proposed a transmission line type microstrip eight port hybrid which is with the proper termination, it can be used as a phase comparator and a Four-way power combiner/divider. Also '1. Kawal, K. Ho, I. Ohta and T. Kaneko have proposed a branch line type eight-port comparator circuit which was composed of four 180' branch line couplers [3]. More recently, A. M. Affandi and G. M. Raw have proposed broadband microstrip eight-port hybrid ring [4] which with the proper terminations can be converted into a phase comparator, 4-way power combiner/divider or six-port reflectometer. II. The Theoretical Analysis of The Non-Uniform Transmission Line Type Eight- Port Circuits Four different configurations of non-uniform transmission line eight port networks are considered here, each one of them will be discussed in more detail latter on. There are two different approaches which be adopted in order to analyze the previous network . The first approach is to convert the proposed eight-port networks into 4-port symmetrical network by employing S. B. Karoomi and Y. Garaultg technique [5], while the second approach is to convert the eight-port circuit into two-port network by dividing the eight-port network about its two-fold symmetry, i.e, about the planes of AAI, and BBI with magnetic or electrical boundary [2], [3]. Once the property of the two planes boundary AAI, and BBI, are defined properly, (i.e. either AIA2, and B1B2, plane have magnetic walls or electrical walls or the combinations) the two port equivalent circuit is known and its scattering parameters can be easily found. The magnetic wall here represent an even-mode while the electrical wall denotes an odd-mode. The non-uniform transmission lines which have been selected here are exponential, linear and parabolic taper transmission lines. III. TheTheoretical analysis of the proposed novel Ultra Broad-Band Exponential Taper Transmission Line 8- Port Network The exponential taper eight-port hybrid is shown in Figure 1. This network is the best described by its scattering parameters which will be computed latter with the aid of the A B C D matrix.Figure 1b shows the photograph of the proposed of the novel Ultra Broad-Band Exponential Taper Transmission Line 8- Port Network. This proposed network is fabricated on Roger 4003 substrate with dielectric constant of 3.38 and the thickness = 0.203 mm.