Dual-Channel Balanced-to-Single-Ended Out-of-Phase Filtering Power Divider-Based High-Gain Dual-Polarized Filtenna Subarray

In this article, we propose an innovative codesign methodology for a high-gain dual-polarized filtenna subarray based on a dual-channel balanced-to-single-ended (BTSE) out-of-phase filtering power divider (FPD). The design begins with the development of a dual-channel BTSE FPD, which integrates a substrate-integrated waveguide (SIW) resonator with four patch resonators. Interchannel isolation is achieved through the orthogonality of the degenerate TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> and TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> modes within the SIW cavity. The four patches are coupled to the SIW cavity via strategically positioned rectangular apertures, organized into two groups. Balanced feeding probes directly coupled to the patches via these apertures, creating a transmission zero (TZ) in the lower stopband. The out-of-phase characteristics of the TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> and TE<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> modes result in a 180° phase difference between the output ports on the patches of each group. By removing the output ports, the signal radiates directly through the patches. Due to the out-of-phase characteristics, the two patches in each group exhibit identical surface current directions, effectively forming a dual-polarized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times 2$</tex-math> </inline-formula> filtenna subarray. Additionally, the introduction of slots on each patch exhibits opposite electric fields near the slots, generating a lower frequency radiation null (RN). By rotating these slots inward, the reshaped TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">02</sub>/TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sub> modes—featuring directional radiation capabilities—are produced alongside the original TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub>/TM<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">01</sub> modes. This creates multiple radiation paths, resulting in an additional in-band resonance and an RN in the upper stopband. To validate the proposed methodology, a prototype is developed, and measured results demonstrate high gain, high selectivity, and excellent polarization isolation.