A Two-Port Microwave Component With Dual-Polarized Filtering Antenna and Single-Band Bandpass Filter Operations

This paper presents a two-port microwave component, which behaves either as a dual-polarized filtering antenna or as a single-band bandpass filter. For the dual-polarized antenna operation, a novel feeding network with a hook-shaped self-coupled line is employed for a pair of magnetoelectric dipoles to obtain filtering radiation performance. This self-coupled line can not only ensure the impedance matching within the passband, but also generate a radiation null at the upper band edge, further suppressing the out-of-band antenna radiation. Since no complex filter circuit is involved in the antenna function design, the in-band radiation performance of the antenna is nearly not affected. Thus, both satisfactory filtering and radiation performances are obtained. With respect to the filter operation, the magnetoelectric dipole of the component does not radiate but functions as the ground of the feeding network, and the feed lines act as two resonators, forming a second-order bandpass filter. For demonstration, the two-port component with both antenna and filter operations is implemented and fabricated. The component has a measured average in-band gain of 7.6 dBi as an antenna, whereas it features a measured in-band insertion loss of less than 1.14 dB as a filter.