Rishi Mishra, A. R. Harish
A tri-band shared-aperture antenna array is proposed in this letter. Band-1 (3.76–4.76 GHz) and Band-2 (5.20–6.45 GHz) antennas are designed such that the structure of one band exhibits a surface-wave electromagnetic bandgap (SW EBG) characteristic for the other band, thereby enhancing inter element isolation when arranged in a triangular 2×4 shared array. Two heterogeneous Band-3 (14.75–15.25 GHz) elements— a microstrip patch and a substrate-integrated waveguide (SIW) cavity slot antenna—are designed and integrated into the Band-1 and Band-2 antenna structures, respectively. Each unit-cell of the Band-1 structure contains four Band-3 patches, while each Band 2 unit-cell incorporates one Band-3 SIW slot antenna. A prototype of a 2×4 shared-aperture array consisting of Band-1 and Band-2 elements with 128 (only 1×8 populated for testing) Band-3 elements is fabricated and tested. Good agreement between simulated and measured results is observed. For the single element, the simulated -10 dB reflection bandwidth of 23.5%, 21.5%, and 3.4% is achieved with peak gains of 10.7 dBi, 9.2 dBi, and 5.5 dBi in Band-1, Band-2, and Band-3, respectively.