Ashok Mittal

Directivity enhancement of circularly polarized microstrip antenna using split ring FSS superstrate

In this paper, a spit ring frequency selective surface is designed to enhance the directivity of a circularly polarized aperture coupled microstrip antenna. In order to characterize the radiation parameters of the proposed structure, a simple ray tracing method is used. It was investigated through simulation that polarization dependent frequency selective surfaces are more capable of reducing the cross polar radiation components, so we have used polarization dependent FSS for this design. In order to achieve circular polarization, we have used two oppositely polarized FSS unit cells so as to nullify the effects of their polarization dependency. Simulation results show that the proposed structure achieves a broadside peak gain of approximately 14 dB for the entire frequency range where the axial ratio is less than 3 dB.

Fan blade shaped slotted patch antenna for wideband circular polarization

A novel structure of a slotted patch antenna loaded with a fan blade-shaped slot for wideband circular polarization is proposed. The proposed structure is aperture fed and matched over a broad frequency band. The antenna exhibits a simulated 3-dB axial-ratio bandwidth of 3.27% (2.41-2.49 GHz) with respect to the axial ratio resonant frequency of 2.45 GHz. The computed 1:2 VSWR bandwidth is 23.67% (2.17-2.75 GHz) with respect to the mid-band frequency of 2.45 GHz. The antenna gain is more than 8.0 dBi in the circularly polarized band.

Dual band π-shaped slotted patch antenna for wireless applications

A new geometry of a square microstrip antenna embedded with a symmetrical n-shaped slot is presented here. The antenna resonates at a dual frequency band from 2.40-2.88 GHz and 3.42-3.58 GHz. This covers the WLAN 2.4-2.5 GHz band, WiMAx 2.5-2.69 GHz band and part of WiMax 3.5 GHz band. The proposed structure is fed with an aperture coupled feed and matched over a broad frequency band using a stub at the open end of the microstrip feed. The antenna gain is more than 7.8 dBi over the dual band. The antenna is suitable for wireless communication systems operating at 2.4/2.5/3.5 GHz band.

Dual-polarized resonant cavity antenna using slotted-circular patch FSS

This paper presents the theory and design of a dual-band dual-polarized high gain Resonant Cavity Antenna (RCA). RCA with slotted circular patch frequency selective surface (FSS) is used atop primary feed i.e., microstrip patch antenna at a height of ~λ/2. The proposed structure is simulated using FEM based HFSS and 3D-EM Solver CST Studio Suite. The slot type defect is introduced in the patch FSS to obtain dualband with orthogonal polarization. It is demonstrated how using a slot, linearly polarized RCA gets converted to orthogonally polarized antenna. A gain of upto 16dB (approx) can be achieved at the two bands with different polarization using this structure. The simulation plots of current density on FSS are also studied, to understand the phenomenon.

An investigation of circular patch antenna on pin-bed type RIS

This paper presents analysis of circular microstrip patch antenna placed over a thin grounded pin bed type reactive impedance surface (RIS). Effect of the variation in the height of the pins on the resonant frequency and the radiation properties of antenna have been studied. 3D EM simulation tools based on finite element method (Ansofts HFSS) and finite integration technique (CST Microwave Studio) are used to model the structure. Magnetic field distribution within the pin-bed substrate has also been studied. 26% compactness has been achieved with the pin bed structure maintaining the gain within an appreciable limit.

An investigation on high-gain dual-polarized cavity reflex antenna using slotted-patch FSS superstrate

This paper presents the analysis of high gain dual polarized cavity reflex antenna (CRA) using two different geometries (i.e. square and circular) of slotted patch type frequency selective surface (FSS) superstrate. A microstrip patch antenna is used as a primary feed for both the configurations. The structures are analyzed using FEM based Ansoft HFSS and 3D-EM Solver CST Studio Suite. The results from both the configurations are compared to understand the effect of FSS unit cells geometry on CRAs performance. It is observed that the geometry plays a significant role, affecting the frequency separation as well as other radiation parameters of the dual polarized antenna. High gain in the range of 16-20dB (approx), is observed from both the configurations for two orthogonal linear polarizations.