A Broadband Magneto-Electric Dipole Transmitarray Antenna with Improved Aperture Efficiency

In this paper, a broadband magneto-electric (ME) dipole transmitarray antenna (TA) with a high efficiency is proposed, whose transmission phase is manipulated by simply varying the length of the delay lines. Operating at millimeter-wave (mm-Wave) frequency band, it is demonstrated that the proposed TA element has a wide 1-dB bandwidth of about 44.4%. Several TA designs with different phase compensation schemes are simulated and compared. The results show that the aperture efficiency of a 16 × 16-element TA adopting the continuous phase adjustment reaches 56.8% with a 3-dB gain bandwidth of 33.9%, covering from 25.5 to 36 GHz. Compared to the 1-bit TA, the aperture efficiency of the proposed TA antenna is significantly improved. Meanwhile, to solve for the bandwidth degradation in large-sized TAs and moderate-sized TAs with small F/D ratio, the true-time delay strategy is adopted. Specifically, a true-time delay moderate-sized TA is designed, simulated and tested. It exhibits a wide operating bandwidth of 32.3%. The demonstrated TA can be a promising candidate for a variety of mm-Wave applications.