Dual-Band Bandpass Filter and Filtering Power Divider With Ultra-Wide Upper Stopband Using Hybrid Microstrip/DGS Dual-Resonance Cells

Abstract

In this paper, two types (i.e., type-A and type-B) of hybrid microstrip/defected ground structure (DGS) cells are proposed for passive circuit implementation with ultra-wide stopband. Both cells consist of the stepped-impedance DGS and embedded folded slotline on the ground, which could obtain the dual-resonances. In type-A cell, a microstrip T-stub on the top side is introduced, which can not only allocate a strong coupling to the DGS with slotline on the bottom side, but also act as the input/output port. To finely adjust the dual-resonances of the type-B cell, a grounded microstrip patch is used. Meanwhile, such compact cells could feature an ultra-wide upper stopband, due to their own slow-wave effect. Based on the aforementioned hybrid microstrip/DGS cells, two dual-band bandpass filters (BPFs) and a dual-band filtering power divider (FPD) are proposed and fabricated. Measured and simulated results are in a fairlyclose agreement. Both dual-band BPFs exhibit the ultra-wide upper stopband, which extends up to 40 GHz with a high rejection level about 30 dB. Besides, the dual-band FPD has merits of more than 18.7 dB of in-band isolation and 28 dB stopband rejection levels up to 40 GHz. INDEX TERMS Bandpass filter (BPF), defected ground structure (DGS), dual-band filter, filtering power divider (FPD), slow-wave, ultra-wide stopband.

Filtering Power Divider With Ultrawide Stopband and Wideband Low Radiation Loss Using Substrate Integrated Defected Ground Structure

“…Note that the electric fields' contribution of SIDGS is mainly restricted in a quasi-cavity by ground II and metal-vias. With such characteristics, the SIDGS can effectively reduce the radiation loss compared with the conventional DGS [25]. Besides, the proposed SIDGS can be easily integrated into passive circuits design due to the surrounding of a complete ground plane.…”

Symmetric 3dB Filtering Power Divider with Equal Output Power Ratio for Communication Systems

“…Two-way integrated FPDs with equal output power ratio have been proposed and achieved in [5]- [7], while those with unequal or arbitrary power ratios have been reported in [8]- [10]. Other papers have reported integrated FPDs that exhibit dual-band filtering characteristics [11], [12]. The integrated FPD reported in this paper is designed to equally divide the input power between the two output ports in the ratio of 1:1.…”

Multiwideband Bandpass Filter Based on Folded Quad Cross-Stub Stepped Impedance Resonator

“…Microstrip filters play a significant role in the multiband microwave filter design because of their advantages in terms of fabrication simplicity, miniaturization, low loss, and low cost [6,7]. Some attractive methods frequently used for the MB-BPF design include quarter-wavelength step impedance resonators (SIRs) [8], trisection SIRs [9][10][11][12], cascaded multiband resonators [13], loaded crossed resonators [14], stub-loaded resonators (SLRs) [15], trimode SLRs [16], stub-loaded quarter-wavelength resonators [17], stub-loaded and defected ground resonators (DGSs) [18,19], and crossed open stubs (COSs) [20][21][22]. e most challenging part of an MB-BPF design is to allow several passbands simultaneously without sacrificing any design freedom or additional drawbacks such as complex geometry and increasing size.…”

“…e most challenging part of an MB-BPF design is to allow several passbands simultaneously without sacrificing any design freedom or additional drawbacks such as complex geometry and increasing size. Recently, some studies of an MB-BPF have been published in [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. e results show a good electrical performance; however, the additional passbands would make the size of the BPF greater and the bandwidth narrower.…”