Three-element filtering antenna array designed by the equivalent circuit approach

This paper introduces a design methodology of a third-order three-element patch array that has no filtering parts and yet behaves like a filtering antenna (filtenna). The design approach includes shaping the frequency response of the reflection coefficient and modeling the frequency response of the normalized realized gain. In order to control the shape of these two responses, gi coefficients of an equivalent low-pass prototype filter are derived for designing the third-order filtering antenna array. The design methodology was verified over the frequency band from 4.8 to 6.8 GHz for levels of the reflection coefficient from −10 to −20 dB and for fractional bandwidths from 7% to 14%. The whole design methodology was supported by manufacturing and measuring three third-order filtering antenna arrays designed with different configurations. The simulated and measured results show good agreement in all cases.