A Wide Beam Printed Quadrifilar Helix based Circularly Polarised Radiating Element for Electronically Steered Antenna

Wide beam and low axial ratio performance of printed quadrifilar antennas result in very attractive circularly polarised radiating element for wide scanned Electronically Steered Antenna. A compact printed quadrifilar Helix antenna (PQHA) has been designed and realised at S-Band frequency. Simulation and optimisation of designed antenna has been performed using ANSYS’s high frequency structure simulation (HFSS) software for its impedance, axial ratio (AR) performance and radiation characteristics. The developed circularly polarised antenna has 3-dB beam width of 130° and peak gain of 3.4dBic at 2.6 GHz. The developed antenna shows excellent AR performance over the frequency band as well as over the radiated beam. Half power axial ratio bandwidth of developed antenna is 27.4% (2.2 GHz - 2.9 GHz) while the impedance bandwidth is 32% (2.1 GHz - 2.9 GHz). Design has been validated through measured results. Designed wide band PQHA can be used as radiating element for electronically steered antenna for large beam steering application

Design and realization of microstrip filters with new defected ground structure (DGS)

In this paper, various microstrip filters, such as bandpass (narrow/wideband) filters, dual band bandpass filter and lowpass filters, are designed with new metal strips loaded defected ground structure (DGS). In this proposed DGS, metal strips are introduced in connecting slot of dumbbell shaped DGS (DB-DGS). This new DGS is an improved version of conventional (dumbbell-shaped) DGS with enhanced characteristics of filters. With this new metal strip loaded DB-DGS, a bandpass (narrow-band/wide-band) filters, dual-band bandpass filter and lowpass filters, are designed with improved characteristics. The entire proposed filters are designed and fabricated with the same substrate area using 50 Ω, λg/4 microstrip line which is very compact to conventional microstrip filters. For validation of proposed designs, all fabricated filters are measured in Rohde and Schwarz Vector Network Analyzer 1127.8500 and also compared with circuit simulated results. All the simulations are carried out in HFSS V10 and ADS2006A

Investigation on microstrip filters with CSRR defected ground structure

This paper consists the design studies of complementary split ring resonator (CSRR) defected ground structure (DGS) microstrip filter with low insertion loss in the passband and high rejection in stopband with a comparison of various CSRR-DGS structure has been proposed. Various parameters of microstrip filters have been studied with CSRR-DGS such as roll off rate, bandwidth, effective inductance and capacitance. On the basis of these studies, microstrip low-pass, bandpass and dual-band bandstop filters have been designed and realized with enhanced properties of filters.clos