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° can be achieved. To evaluate the effectiveness of the TTD technique compared to the traditional method with phase truncated within 360°, 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.