A dual mode shared aperture antenna consisting of two planer arrays of ring antennas is designed for L and S bands. The array of larger dimension surrounds the array of smaller dimension. The antennas are isolated from one another and fed separately. The antenna dimensions are optimized and prototyped. The antennas radiate separately in L and S bands with least coupling or no coupling. Measured results are in agreement with the simulations, depicting good performance in terms of impedance bandwidth, isolation, and gain.

Abstract-This paper presents the design of a novel wideband gap coupled sectoral antenna for communication systems. The circular patch is placed in the aperture of four sectoral rings. The antenna parameters are optimized using various simulations to attain good return loss and corresponding resonant frequency. The antenna operates in X-band at 10.35 GHz showing wideband characteristics along with high directivity and reduced side lobe level to a good extent. The antenna has also been studied using fuzzy inference system (FIS). The return loss and analogous frequency obtained from simulated results and fuzzy system are compared and in good agreement. Design is extended to an array of nine elements mutually coupled to the active fed patch. The antenna is fabricated, and the simulated results are found to be in good agreement with experimentally measured ones. A bandwidth of 900 MHz at resonant frequency of 10.35 GHz with a directivity of 7.0 dBi and reduced side lobe level of −18.9 dB is therefore obtained.