Dual‐frequency dual‐polarised shared‐aperture microstrip antenna array with suppressed higher order modes

Here, a dual‐frequency dual‐polarised shared aperture microstrip antenna (DFDP‐SA MSA) at S‐ and X‐bands with suppressed higher order mode is presented. The technique for higher order mode suppression comprises of a microstrip filter within the antenna, which eliminates the need of a separate RF filter in the transmitter/receiver chain. The antenna operates at two frequencies having high‐frequency ratio of 1:3.2 between them, which is utilised to its advantage by using cross‐shaped antenna at S‐band and 2 × 2 array of square patches at X‐band around it. This antenna gives measured bandwidth ( | S 11 | ≤ − 10dB ) of 7.4% from 2.6 to 2.8 GHz (S‐band) with measured gain of 8 dBi at 2.5 GHz and measured isolation better than 18 dB between the orthogonal ports at S‐band. It gives bandwidth of 8.7% from 7.7 to 8.5 GHz (X‐band) with measured gain of 11.5 dBi at 8 GHz and measured isolation better than 28 dB between the orthogonal ports at X‐band. The antenna is extended to 2 × 2 array for higher gain.