Wideband Evanescent Mode Bandpass Filter Based on Double Ridge Rectangular Waveguide Partially Loaded With Broadside Printed Strips
IEEE Microwave and Wireless Technology Letters, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Publication Date: 2026
- Doi Number: 10.1109/lmwt.2026.3697602
- Journal Name: IEEE Microwave and Wireless Technology Letters
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Keywords: Evanescent mode filter (EMF), hybrid technology, miniaturized, ridge waveguide, wide stopband, wideband
- Hacettepe University Affiliated: Yes
Abstract
The double ridge rectangular waveguide (DRRW) partially loaded with a dielectric substrate on which broadside copper strips are printed is presented for the evanescent mode filter design with a wide passband and a wide spurious-free stopband. Broadside strips printed on the substrate miniaturize the DRRW and cause the monomode bandwidth of the DRRW to widen. The filter topology is based on creating empty evanescent mode DRRW sections along the longitudinal direction of the broadside printed strips loaded-DRRW (BPS-DRRW) by cutting the corresponding parts of the printed circuit board (PCB) off. The PCB is sandwiched between the upper and lower rigid metallic parts of the DRRW. Conducting posts at the edges of the substrate ensure the continuity of the narrow wall current. A fifth-order, all-pole bandpass filter with input/output microstrip line transition circuits is designed for a passband of 2.5–3.5 GHz and a wide spurious-free stopband up to 18 GHz with a rejection greater than 25 dB.