A Compact Quad-Band Bandpass Filter Using Multi-Mode Stub-Loaded Resonator

Abstract

Abstract-This paper presents a compact shorted stub-loaded quad-band bandpass filter. The proposed filter simultaneously operates at GSM (0.83-0.97 GHz), LTE2300 (2300-2400 MHz), WiMAX (3.3-3.7 GHz), and WLAN (5.725-5.825 GHz) bands. The filter has been designed using the technique of stub-loaded resonator (SLR). By changing the length of the center-loaded stub, the resonant frequency of the even-mode can be varied without affecting that of the odd-mode. This simplifies the design and tuning of the quad-band filter. Eight transmission zeros (TZs) around the three passband make the pass bands highly isolated. In order to validate its practicability, a quad-band bandpass filter (BPF) has been designed, fabricated and measured. Good agreement between simulated and measured results is observed.

Multi-Band Bandpass Filter Using Novel Topology for Next-Generation IoT Wireless Systems

“…Nowadays, researchers are more focused on developing miniaturized quad-, penta-, and sext-band BPFs. Different design topologies have been adopted to develop quad-band BPF [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. A popular method to design a quad-band BPF is by using stub-loaded topology [9][10][11][12][13].…”

“…Different design topologies have been adopted to develop quad-band BPF [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. A popular method to design a quad-band BPF is by using stub-loaded topology [9][10][11][12][13]. In [9], a quad-band BPF with only three finite frequency transmission zeros using symmetrical stub-loaded topology has been presented.…”

“…However, each band's insertion loss and selectivity are not good enough. In [12], another quad-band BPF has been presented using a stub-loaded resonator. The even and odd mode method is used to analyze the symmetrical structure.…”