A novel microstrip band‐pass filter based on hole coupling structure

Abstract

A novel C-band hole-coupled bandpass filter with metallized post (or via-hole) arrays directly embedded in middle of the microstrip line is presented in this letter. The proposed filter removes via-hole arrays embedded along waveguide section from the half-mode substrate integrated waveguide filter, while the new concept simplifies the structure of previous filter. Simulated and experimental results show that the proposed filter of this paper has good performances of low insertion loss, return loss, and better rejection characteristics. The insertion loss of measured four-pole filter is about 0.8 dB, and the return loss is better than À25 dB in the whole passband. Keeping the advantages of excellent performances, the proposed filter can be constructed more conveniently and is suitable for low-cost planar circuit.ABSTRACT: This article presents a design for wideband bandpass filters using a microstrip cavity coupler. The broadband nature of the cavity-coupled designs is fully exploited for this application. Two additional circuits are introduced to improve the stopband performance of the cavity-coupled bandpass filter. A prototype design example is presented with its center frequency located at 6.28 GHz. The design has the merits of wide bandwith of more than 140%, flat group delay within the passband, good insertion/return loss, and stopband attenuation of nearly 30 dB up to 30 GHz. The validity of the simulation results is verified experimentally.

Miniaturized W‐band bandpass filter based on rectangular micro‐coaxial structure

“…Since the basic Chebychev filter theory is well known, the parameters in the formulas refer to. 15,16 In addition, parameters l i and λ g0 represent the length of transmission line between grounded cylinders and the wavelength of proposed filter at center frequency respectively. To determine dimensions of the third-order resonant structure, the following steps based on the above analysis are carried out.…”

“…Next, we use the equivalent circuit method to synthesize the initial dimensions of the resonant structure, [15][16][17] as shown in Figure 4. The grounded cylinder with a short section of rectangular micro-coaxial transmission line around it can be equivalent to a K inverter, which is presented in Figure 5.…”