A Wideband Transmitarray Antenna Based on True-Time Delay Magneto-Electric Dipole Elements

In this brief, a millimeter-wave (mmWave) wideband transmitarray antenna (TA) based on true-time delay (TTD) magneto-electric (ME) dipole elements is proposed. The TTD element is composed of two identical ME dipole with L-shaped probes connected by a time-delay stripline. By adjusting the length of the stripline, a phase shift of over 1200 degrees can be achieved. To evaluate the effectiveness of the TTD technique compared to the traditional method with phase truncated within 360 degrees, several TAs with different F/D ratios have been analyzed using an in-house algorithm based on aperture-field method. The numerical results reveal that the TTD technique enhances the gain bandwidth of the TA. Furthermore, a TA prototype with a quasi-circular aperture consisting of 904 elements is designed, fabricated, and tested for demonstration, with an F/D ratio of 0.8. The measured results exhibit a 3-dB bandwidth of 40.7% spanning from 23.5 to 35.5 GHz and a peak gain of 32.6 dBi, corresponding to a maximum aperture efficiency of about 41.4%, highlighting the potential of the proposed TA for mmWave applications.