The Compact Balanced Filtering Power Divider With In-Phase or Out-of-Phase Output Using H-Shape Resonators

In this paper, the compact balanced filtering power dividers using four coupled H-shape resonators and two resistors are proposed. The theoretic coupling topologies of the proposed designs are given and analyzed. Meanwhile, the phase feature of the filtering structure formed by the electric or magnetic coupling is studied. The main advantages are compact size, both in-phase and out-of-phase output, wideband isolation, and wideband out-of-band suppression when compared with the reported designs. For demonstration, one in-phase prototype with the size of 0.36 λ_g × 0.22 λ_g and one out-of-phase prototype with the size of 0.34 λ_g × 0.22 λ_g are fabricated and measured (λ_g is the guided wavelength at the center frequency). The in-phase (out-of-phase) design exhibits the insertion loss of 2.2 dB (2 dB) at the center frequency, the 3-dB bandwidth of 6.6% (7.4%), the 20-dB stopband of 2.7f₀ (2.3f₀), and the 15-dB isolation band of 4.9f0 (4.74f₀).