Various center edge shorted microstrip antennas backed by modified ground plane are analyzed from compactness and polarization purity point of view. The optimum results are obtained for the dual H-shape ground plane profile antenna, amongst all, which yields 44 dB reduction in the cross-polar level at the broadside direction. Empirical formulas are derived to estimate the resonant length at the fundamental and higher-order mode frequency of shorted antennas backed with different ground plane profiles. Simulated resonant frequencies closely match with those computed by using proposed formulas in each case. Thus, the proposed formulas can be applied to design compact antennas operating at any desired frequency based on the application.

This paper presents multichannel multi cavity modeling technique (MCMT) analysis of cross channel interference in Ka band. The Multi cavity modeling technique is used to analyze the channel interference at waveguide joints. Waveguides are used as transmission line in microwave communications, broadcasting and RADAR installation. When two channel waveguides are joined together the phenomenon of cross channel interference will certainly appear and the reason behind is faulty workmanship. The Gap appears at the flange joint causes power coupling to the neighboring ports. In this paper two channel E-plane waveguide joints for frequency range 26 GHz to 29 GHz has been analyzed. Scattering parameters data obtained from MCMT analysis has been verified and compared with CST microwave studio simulated data and measured data.

In this paper, miniaturized tri-band Circularly Polarized (CP) staired Rectangular Dielectric Resonator Antenna (RDRA) using novel design feed network of trisection Wilkinson Power Divider (WPD) with wideband 900 phase shifter is developed for navigation satellite applications at L5-band (1.164 to 1.188 GHz), L1-band (1.565 to 1.585 GHz) and S-band (2.48 to 2.5 GHz). For tri-band RDRA, the ground plane size is reduced to 40 mm x 40 mm at lower resonance frequency of 1.176 GHz using high dielectric constant (er = 51.92) of dielectric resonator material and dielectric substrate (es = 10.2) (Rogers RO3210). Ground plane area and volume of RDRA are achieved small compared to published research works. Circular polarization of tri-band RDRA produces in L5-, L1- and Sband using novel design feed network trisection WPD with wideband 900 phase shifter. Far field radiation patterns of tri-band RDRA are obtained from electric field distribution of TEy111 , TEy113 and TEy112 modes at center frequencies of 1.176 GHz, 1.575 GHz and 2.49 GHz, respectively. Simulated Return Loss (RL) of triband RDRA is achieved to be more than 10 dB over L5-, L1- and S-bands. The simulated peak Right Hand Circular Polarization (RHCP) gain is varying between 0.92 to 2.3 dB over all bands. Simulated Axial Ratio (AR) is obtained to be lower than 3 dB overall band. Tri-band RDRA is analyzed, fabricated and tested. Various parameters such as RL, RHCP-LHCP (Left Hand Circular Polarization) far field radiation patterns, RHCP gain and AR of tri-band DRA are obtained simultaneously over L5, L1 and Sbands as per design technical specifications that’s novel contribution.

Branch line couplers are 3 dB directional couplers. They have varied applications like power dividers, power combiners, monitoring power flow in microwave measurements, etc. A conventional branch-line coupler is designed for WiMAX applications (3.5GHz) using commonly available FR4 substrate. Then a compact branch-line coupler is designed using an equivalent pi-network of high impedance line and shunt capacitances. When compared to other methods, this method has less design complexity, no modification of ground is needed and the designed structure is planar. This method provides 31% size reduction.