Dual Band H-Shaped Antenna-Filter-Antenna based Frequency Selective Surface for Q-Band Applications

a multi-layer antenna-filter-antenna (AFA) based frequency selective surface isproposed for Q – band applications, consisting of dual bands. The elementary cell consisting of two micro strip patch antennas and a non-radiating resonant structure in the form of H shape. The design is simulated with the help of ANSYS-HFSS simulation software. The simulated results give two bands (37.9GHz-39.4GHz & 43.7GHz-44.9GHz). The simulation results gives a 22.6% 3-dB (3.88% &2.7% 10-dB for two bands) bandwidth. IndexTerms—Antenna-filter-antenna, Frequency-selective-surfaces. Introduction The main part of the proposed method is Antenna-Filter-Antenna (AFA) elementary cell. It consists of three elements namely a receiving antenna operating at input port, a resonant structure which is not radiating and a transmitting antenna operating output port [1]. For realization of transmit array antennas (TA) [2], the elements of the cell can be configured in non-uniform arrays. In order to realize the frequency selective surfaces (FSS) [3], we can configure the elements of the cell in uniform arrays. Planar periodic structures are used for to realize the FSS. The FSS can be considered as filters with radiative ports. Based on the geometry, a bandpass or band elimination response is obtained by a single layer FSS around its resonance frequency. The metallic structure consists of three layers. The two patch antennas are presented at bottom and top layers and the middle layer consists of three slot resonators in the form of H-shape. Transfer function of the bandpass filter obtained from transmit array AFA elements. For satellite [4], power combining and radar [5] applications, the characteristics of bandpass filter are more desirable. The heat dissipation and power handling in the structure can be improved by the distributed nature of transmit arrays. Multi-layer FSS structures [6-7] are used for design of high order filters because the computational complexity dramatically rises. By combining the individually designed FSS layers gives a high order FSS. A thick dielectric slab of thickness (0.2-0.3λ0) is used to stack the each of the FSS layers resonators. Normally the dielectric slab acts as an impedance inverter. All these arrangements will create a multipole filter. This method has multiple problems as given below:  The very first problem is that the filter topology so obtained is a sequence of resonators and inverters which can be used for a constrained class of filter responses which reduces the design space significantly.  The second issue is that the simple resonator inverter interpretation is not valid because of the direct near-field coupling present between the layers of FSS in the stack.  Finally the structure looks bulky and thick hence it is not preferable for more applications. In this paper we presented our approach to design a dual band Antenna-Filter-Antenna element. The elementary cell is a threelayer structure composed of two patch antennas and co-planar waveguide (CPW) resonators (the coupling slots are in the form of Hshape). The results obtained for this design are simulated results only. www.ijcrt. org © 2018 IJCRT | Volume 6, Issue 1 March 2018 | ISSN: 2320-2882 IJCRT1803106 International Journal of Creative Research Thoughts (IJCRT) www.ijcrt. org 41 Fig. 1. An array of AFA modules as a bandpass FSS.