Xue‐Shun Zhang

Compact dual-band BPF for GPS and WLAN with two dual-mode stepped impedance resonators

A compact dual-band microstrip bandpass filter (BPF) is proposed using two dual-mode stepped impedance resonators (SIRs). Either of the dual-mode SIRs can not only separately generate one passband but also control the passband performance. Due to the intrinsic characteristics of the SIRs and source-load coupling, three transmission zeros are created near the passband edges to improve the selectivity of the filter. A dualband filter located at 1.57GHz (GPS application) and 2.40GHz (WLAN application) is simulated and fabricated. Good agreements are obtained between its measured and simulated S-parameters.

Compact and high selectivity dual mode microstrip filter with source-loaded coupling

In this letter, a novel compact and high selectivity microstrip filter with source-loaded coupling is proposed using miniaturized dual-mode resonator. The resonator can generate one odd-mode and one even-mode in the desired band. Two resonant frequencies can be adjusted easily to satisfy the bandwidth of the BPF. A transmission zero is created near the lower cut-off frequency due to the main path signal counteraction. Two additional transmission zeros attributed to source-loaded coupling are generated near the upper cut-off frequency and in the upper-stopband. A dual-mode filter is simulated, fabricated and measured. The EM simulated and measured results are presented and excellent agreement is obtained.

Cross-coupled UWB bandpass filter with dual-mode stepped impedance resonator

In this paper, a new three-mode ultra wideband (UWB) bandpass filter (BPF) with compact size and highly selectivity is proposed using dual-mode stepped impedance resonator (SIR). The resonator, configured by two sections big impedance ratio transmission lines, generates two operating modes in the desired band and the even-mode frequency can be tuned effectively by adjusting the length and width of the low impedance line if keeping the perimeter unchanged. In order to obtain a good in-band and high selectivity performance, a cross-coupled feed structure is applied to generate a reflection zero in passband and two transmission zeros at the lower and upper stopband. By properly optimizing the structure by HFSS, an UWB BPF with 1dB fractional bandwidth 56% from 3.1 to 5.7 GHz, group delay between 0.25 and 0.45ns, and return loss better than 15dB is presented.

Compact quadruple-mode UWB bandpass filter using open stub loaded multiple-mode resonator

In this paper, a compact quadruple-mode ultrawideband (UWB) bandpass filter (BPF) is designed by using open stub loaded multiple-mode resonator (MMR). The proposed MMR possesses the advantage that odd-mode resonance frequencies exclusively depend on the traditional MMR; even-mode resonance frequencies can be flexibly controlled by impedance-stepped stub, whereas the odd-mode ones are fixed. By simply adjusting the dimension of the impedance-stepped stub, the fourth resonant mode falls down and works together with the first three modes to form a novel quadruple-mode UWB filter. Two other pairs of open stubs are mainly applied to adjust the high resonant modes and obtain good match, respectively. The filter using open stub loaded MMR is simulated, fabricated and measured. The EM simulated and measured results are presented and excellent agreement between them is obtained.