This letter proposes a novel wideband 360° filtering phase shifter (FPS), which combines a reflection-type phase shifter (RTPS) and two switch-type phase shifters (STPSs). The RTPS is based on a filtering magic-T configuration with varactor diodes on the collinear ports, which simultaneously realizes the filtering function and 0°–90° phase shift. Then, a 180° STPS and a 90° STPS are cascaded with the RTPS to form the proposed wideband 360° FPS. It achieves a full 360° continuous phase shift and good frequency selectivity within a wide passband. For demonstration, a prototype of the proposed wideband 360° FPS was fabricated and measured. The measured results show that the prototype operates over a 2–3-GHz bandwidth with a 40% fractional bandwidth (FBW), exhibiting a maximum in-band phase error of ±6.14°, a root-mean-square (rms) phase error of 3.55°, and a return loss (RL) better than 10 dB.

This article presents a novel compact high-Q bandpass filter (BPF) utilizing a 3-D stacked stripline configuration. T-shaped stepped impedance resonators (SIRs) are employed to achieve miniaturization. By folding the filter geometry from an inline arrangement into a U-shape along the broadside direction, both broadside and edge coupling structures are realized, enabling various cross-coupling schemes for flexible placement of transmission zeros (TZs). A comprehensive analysis of both electric and magnetic coupling structures is conducted to support the overall filter design. To validate the concept, a tenth-order general Chebyshev BPF prototype centered at 3.485 GHz with a 1 dB bandwidth of 380 MHz is designed, fabricated, and measured. The filter is constructed by vertically soldering two patterned sheet metal layers together with three stacked cavities. Despite having an electrical size of only 0.58 × 0.23 × 0.19 λ_g³, the filter exhibits a high unloaded Q-factor (Q_u) of 1200, along with up to six TZs and a spurious-free frequency range extending to 12 GHz. Measured results show an insertion loss of 0.58 dB at the center frequency and a return loss of better than 20 dB within the passband, demonstrating favorable agreement with simulations. Featuring solid electrical performance, the proposed filter is ideally suited for 5G and 5G-Advanced (5G-A) communication base stations.

This letter presents a tunable notch band ultra-wideband (UWB) filtering balanced power divider (FBPD) using a hybrid microstrip/slot-line structure for effective common-mode (CM) suppression and differential-mode (DM) transmission. The innovative design enhances upper stopband suppression by incorporating a pair of open-circuit stubs on each side of the microstrip structure. Additionally, a short-circuit stub loaded with a varactor diode enables tunable notch band functionality. This configuration achieves a wide upper stopband and a tunable notch band with excellent frequency selectivity, enhancing versatility over conventional designs. Finally, the proposed UWB FBPD was fabricated and measured. The measurement results show a 120% DM 3dB fractional bandwidth (FBW). The CM suppression exceeds 28.7dB over the 2–8GHz passband, and the DM upper stopband suppression exceeds 20.7dB up to 20GHz (4f0). The DM isolation exceeds 14.1dB within the passband, and the notch frequency (NF) is tunable from 4.5 to 5.4GHz.