Novel multi-functional and compact waveguide filter based on various<i> meta</i>-resonators for C-band applications

This paper presents the design, fabrication, and performance analysis of a novel, multi-functional WGF for Cband (4.90-7.05 GHz) applications. The novel WR-159 WG structure is precisely fabricated from Al6065 material by the CNC milling method, and also meta-resonator structures designed in different sizes and geometries are fabricated from low-loss Duroid/RT 5880 substrate material with help of LPKF. Thanks to the designed single WR-159 WG structure, the WGF with four different functions is experimentally realized using a set of metaresonators that can be mounted and dismounted. These four functions are bandpass/bandstop, narrow/medium/ wide bandwidth, shifting operating frequency (5.5, 6, and 6.5 GHz), and filter order (n = 1-7). Filter performance has been verified through simulations and measurements with a vector network analyzer (VNA). For each WGF designed for different functions, simulated and measured performance results, such as for center frequency (f0), return loss (RL), insertion loss (IL), fractional bandwidth (FBW), and quality factor (Q) are compared, and they have good agreement with each other. The proposed modular structure offers a low-cost and versatile alternative that can replace commercial filters.