A Design of a Dual-Band Bandpass Filter Based on Modal Analysis for Modern Communication Systems

Abstract

A dual-band bandpass filter (BPF) composed of a coupling structure and a bent T-shaped resonator loaded by small L-shaped stubs is presented in this paper. The first band of the proposed BPF covers 4.6 to 10.6 GHz, showing 78.9% fractional bandwidth (FBW) at 7.6 GHz, and the second passband is cantered at 11.5 GHz with a FBW of 2.34%. The bent T-shaped resonator generates two transmission zeros (TZs) near the wide passband edges, which are used to tune the bandwidth of the first band, and the L-shaped stubs are used to create and control the narrow passband. The selectivity performance of the BPF is analyzed using the transfer function extracted from the lumped circuit model verified by a detailed even/odd mode analysis. The BPF presents a flat group delay (GD) of 0.45 ns and an insertion loss (IL) less than 0.6 dB in the wide passband and a 0.92 IL in the narrow passband. A prototype of the proposed BPF is fabricated and tested, showing very good agreement between the numerically predicted and measured results.

Compact wideband Wilkinson power divider on gallium arsenide‐based integrated passive device technology

“…The even-odd mode analysis method has a good application in the design of microwave passive circuits and is widely used in the symmetrical circuits of two-port filters and three-port power dividers. [25][26][27][28] The network is divided into two identical networks by a symmetric reference plane. In the odd-mode state, the reference surface is equivalent to an ideal electric wall, which is equivalent to a short circuit.…”

Compact Bandwidth Enhanced Cavity-Backed Magneto-Electric Dipole Antenna with Outer Γ-Shaped Probe for GNSS Bands

“…At 1.04 GHz, the dominant current is at the edge of the horizontal plates and rotates; this behavior is also observed at 1.16 GHz, where the horizontal and vertical parts are near their resonance frequencies. At 1.27 GHz, we can observe the strongest currents on the vertical part of the magneto-electric struc- This technique, also used in microwave engineering (e.g., [20]), allows the identification of strong currents on the structure for specific frequencies and helps with comprehension of working mechanisms involved. At 1.04 GHz, the dominant current is at the edge of the horizontal plates and rotates; this behavior is also observed at 1.16 GHz, where the horizontal and vertical parts are near their resonance frequencies.…”

“…To understand the working process of the antenna, the current distribution of the antenna for resonance frequencies is shown in Figure 5. This technique, also used in microwave engineering (e.g., [20]), allows the identification of strong currents on the structure for specific frequencies and helps with comprehension of working mechanisms involved. At 1.04 GHz, the dominant current is at the edge of the horizontal plates and rotates; this behavior is also observed at 1.16 GHz, where the horizontal and vertical parts are near their resonance frequencies.…”

Compact Double Notch Coplanar and Microstrip Bandstop Filters Using Metamaterial—Inspired Open Ring Resonators

“…However, most of these designs have relatively large size and high insertion losses, because they are based on several elements inserted in series in the propagation line. Examples of these designs include cascaded stepped-impedance resonators [2][3][4], open stubs filters [5], open loop resonators [6,7], T-shaped resonators [8], and cascaded split-ring resonators [9]. Several design techniques for controlling the resonances by means of even and odd mode analysis [10,11], or the frequency response by using an analysis of the transfer function [12,13], have been proposed.…”