Wideband gap coupled microstrip antenna using RIS and RIS cavity resonator

This paper presents a wideband gap coupled microstrip antenna. FR4 substrate is used to fabricate the micro strip antenna (MSA) and placed 1.5 mm above ground plane which improves the antenna efficiency and its bandwidth. An array of square patches is fabricated on bottom side of FR4 substrate with inter element spacing between them. RIS reduces the coupling between the ground plane and MSA patch and therefore increases the bandwidth of antenna. This MSA with RIS is placed in RIS cavity resonator to increase the bandwidth of the antenna. Parasitic patches are gap coupled to both radiating edges of fed patch of MSA. Dielectric rods are used at edges with air gap between superstrate layer and ground plane. The VSWR is less than 2 is obtained over 4.704-6.512 GHz, which covers bandwidth of 1.8 GHz also provides uniform gain over bandwidth. The overall bandwidth contains 5.15-5.35 GHz ISM, 5.725-5.875 GHz ISM band and 5.9-6.4 GHz C band. The antenna provides VSWR less than 2 dB and greater than 75 % efficiency of antenna.