3-D-Printed Ka-Band Circularly Polarized Monopulse Antenna Array With High Gain and Low Axial Ratio

In this article, a 3-D-printed $16\times 16$ circularly polarized (CP) monopulse antenna array is investigated in the Ka-band, featuring high gain and low axial ratio (AR). The monopulse antenna array comprises four low-profile left-handed CP subarrays and a sequential rotation comparator network (SRCN). The four subarrays are connected orthogonally to the SRCN outputs, enabling simultaneous phase relationship integration between the traditional 2-D monopulse antenna array and the sequential rotation network. To verify the design concept, a $16\times 16$ monopulse antenna array prototype is monolithically fabricated by selective laser melting (SLM) 3-D printing technology. The measured results show that the proposed monopulse antenna array achieves a shared bandwidth (return loss >10 dB) from 27.5 to 30.0 GHz for both sum and difference input ports. The left-handed CP gain reaches up to 32.3 dBic with an in-band AR lower than 0.3 dB. The null depth is approximately −24 dB and the total efficiency is over 70%. The advantages of the proposed monopulse antenna array, including high gain, excellent CP purity, high efficiency, and substantial power capacity, are particularly well suited for satellite communication systems.