In this paper, a high-isolated dual-polarized leaky-wave antenna (LWA) with a fixed beam is proposed for full-duplex millimeter-wave applications. The proposed antenna consists of a dual-polarized LWA array and an orthogonally differential feeding network. The proposed dual-polarized LWA array is developed based on the proposed LWA unit cell, which is suitable for differential feed, and the open-stop band is eliminated. The proposed feeding network provides two pairs of orthogonally differential excitation for the LWA array to realize the fixed beam with orthogonal polarization in boresight direction; the high inter-port isolation is implemented as well. The prototype for demonstration purposes is fabricated and measured. The measured results show that the proposed antenna exhibits an operating band from 27.6 GHz to 29.5 GHz with a maximum gain of up to 24 dBi. Furthermore, the measured inter-port isolation is higher than 51 dB within the operating band, where the maximum isolation is up to 60 dB. The measured cross-polarization levels are also very low, less than −27 dB. The proposed antenna features high gain, high inter-port isolation, and good co/cross-polarization isolation, achieving a good Tx/Rx separation for the in-band full-duplex applications at millimeter-wave frequencies.

Facing the demand for decoupling and filtering for large-scale antenna arrays in modern communication systems, a transmission-line-based scheme is proposed and studied in this article. Different from other decoupling networks published recently featuring narrow decoupling bandwidths and high spurious levels, the proposed approach uses simple T-shaped networks where decoupling and filtering responses are realized simultaneously, leading to high frequency selectivity and improved decoupling bandwidth. The proposed design is a simple one-dimension configuration but powerful for two-dimension arrays. Based on the study case of a 4×4 dual-polarized patch array, theoretical analysis and full-wave simulation are carried out to verify the performance in the decoupling and frequency selectivity of this method. A prototype is further fabricated, assembled, and measured to demonstrate the performance of the proposed method in practice. The measured and simulated results are consistent with each other where a low insertion loss of around 0.6 dB is observed. The results denote that the proposed method is easily realized with a very small effect on the radiation performance of antenna elements, making it to be a potential and valuable decoupling and filtering solution for large-scale arrays.

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