Compact Square Substrate Integrated Waveguide Filtering Power Divider With Wideband Isolation

• Published in: IEEE microwave and wireless components letters Vol. 31; no. 2; pp. 109 - 112
• Main Authors: Liu, Bao-Guang, Lyu, Yun-Peng, Zhu, Lei, Cheng, Chong-Hu
• Format: Journal Article
• Language: English
• Published: IEEE 01.02.2021
• Subjects: Coplanar waveguides; Filtering power divider (FPD); Loss measurement; Passband; Resistors; Resonant frequency; square substrate integrated waveguide (SIW) cavity; Substrates; wide stopband; Wideband; wideband isolation
• ISSN: 1531-1309; 1558-1764
• DOI: 10.1109/LMWC.2020.3042332

In this letter, a new compact filtering power divider (FPD) on the square substrate integrated waveguide (SIW) with wideband isolation is proposed. As the isolation network is embedded in a square SIW cavity, good in-band isolation, compact structure, and low insertion loss can be simultaneously attained. The proposed FPD consists of the coplanar waveguide feeding line of Port 1, the capacitor, a resistor, and the square SIW cavity. TE 101 , TE 201 , and slot-line modes can realize third-order filtering response. Center frequency (<inline-formula> <tex-math notation="LaTeX">f_{0} </tex-math></inline-formula>) and bandwidth of the filtering response can be independently adjusted. In order to achieve out-of-band isolation, Port 2/3 is placed in the specific position to suppress the high-order modes according to the electric-field distributions of these modes. Finally, a prototype with in-band return loss of 20 dB across 5.59-6.4 GHz is designed at 5.99 GHz. The bandwidths of isolation higher than 21 dB and upper stopband attenuation higher than 20 dB are extended to <inline-formula> <tex-math notation="LaTeX">2.79f_{0} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">2.83f_{0} </tex-math></inline-formula>, respectively.