A Comparative Investigation of Conventional and Dual Differential-Fed 2×2 Phased Arrays

In this paper, a comparison between conventional 2×2 phased array and dual differential-fed 2×2 phased array is presented from the perspective of system effective reflection coefficient (S
eff
), axial ratio (AR) for both circular polarization (CP) and linear polarization (LP), and directivity. It is shown that S
eff
can be a useful tool to evaluate the combined effects of single element ports isolation, individual port matching, and mutual coupling between the patch elements. When reducing the mutual coupling by increasing elements spacing, S
eff
can be improved while limited by single element ports isolation. Isolation levels beyond -60dB are shown for the proposed dual differential-fed phased array, which is superior to the isolation level of the conventional 2×2 phased array. Moreover, the AR of the proposed dual differential-fed phased array is almost 0dB for CP and nearly 60dB for LP, and its AR is immune against mutual coupling.