A Wideband Microstrip Array Design Using RIS and PRS Layers

In this letter, a wideband microstrip antenna (MSA) array using reactive impedance surface (RIS) and partially reflecting surface (PRS) is proposed. The antenna with RIS and PRS provides wider impedance bandwidth (BW), less gain variation, and further miniaturization compared to antenna with single RIS. The proposed antenna provides 24.3% impedance bandwidth, which covers the frequency band from 5.14 to 6.56 GHz. Maximum gain of 12.5 dBi with less than 1.1 dB gain variation over three individual bands viz. 5.15-5.35 GHz (ISM), 5.725-5.875 GHz (ISM), and 5.9-6.4 GHz (satellite uplink) is achieved. Broadside radiation patterns have sidelobe level (SLL) <; -20 dB, cross polarization <; -15 dB, and front-to-back lobe ratio > 20 dB. The overall antenna dimensions are 1.55 λ
₀
× 1.55 λ
₀
× 0.11 λ
₀
, where λ
₀
is the free-space wavelength corresponding to 5.85 GHz, central frequency of the operating frequency band. The structure is fabricated and tested, and the measured results agree with simulation results.