A Triband Multifunction Frequency Selective Surface

In this paper, a Triband Multifunction Frequency Selective Surface (TMFSS) is proposed. There are four number of p-i-n diodes used in TMFSS unit cell which are biased on parallel biasing principle. Between 1~2.0 volts are required only to feed the diodes in a layer of full board. Three bands can be selected for transmission and reflection in multiple ways along with polarization control. The operating bands work at 2.0 GHz, 3.9 GHz and 5.0/5.47 GHz frequencies. Multiple codes are assigned on the basis of biasing to p-i-n diodes and working principle of TMFSS in terms of different behavior. The codes 0000 and 1111 meet transmission through TMFSS at 3.9 GHz and 5/5.47 GHz to dual polarizations of plane wave, respectively. Meanwhile, both states reflect frequencies other than their selected transparent windows. The codes 0011 and 1100 supply polarization asymmetry besides switching between two bands residing at 3.9 GHz and 5.47 GHz frequencies. The codes 1011 and 1101 provide polarization inversion and switching at 2.0 GHz. However, these codes provide dual polarization transparency at about 5/5.47 GHz with little drift in center frequency. The code 0001 is transparent for TE wave at 2.0 GHz and 5 GHz. This code reflects the 3.9 GHz band at which the TMFSS is transparent to TM wave. The code 1000 makes the TMSSS transparent for TM wave at 2.0 GHz and 5.0 GHz. This code reflects the TM wave at 3.9 GHz band at which the TMFSS is transparent to the TE wave. For the code 1010 = 0101, the TMFSS acts transparent to any polarized wave at 2.0 GHz and 5.0 GHz frequencies, whereas this code reflects rest of frequency waves with any polarization. Insensitivity of TMFSS approaches to 45. oblique anzles,

I. Introduction

Frequency Selective Surfaces (FSSs) can be used to design first, second or higher order filters with single, double or multilayer arrangements, respectively [1]–[6]. Multiple com-binations of transmission, reflection, polarization conversion and absorber/rasorbers etc., are also possible with mixture of metallic resonant or non resonant elements and choice of dielectric materials. The proper organization of microstrips and patches provide single, dual and multi band filters within a unit structure [7]–[10]. Based on the order, filter characteristics and number of bands in the filters domain, the FSSs have become most emerging research area. These filters have edge over other kind of filters because of their low profile, less weight, more degree of freedom and ease of fabrication. These filters have also been proposed to be applicable in immense RF/microwave systems [11]–[18].