A compact triple‐mode (TM) bandpass filter (BPF) is designed based on the proposed dual capacitively‐loaded (DCL) substrate‐integrated waveguide (SIW) resonator. Two identical T‐shaped grounded striplines are inserted into a square SIW cavity to generate a capacitively loading effect without damaging cavity surface integrity, which contributes to maintaining EM‐shielding capability. By adjusting the size and position of the DCL structure, the first three resonant modes, including TE101, TE201, and TE301 are easily controlled to design a TM‐BPF. A transmission zero (TZ) is introduced by the grounded striplines and flexibly controlled. TZ is tuned to suppress the TE102 mode to acquire a wide upper rejection band. Furthermore, the filter design procedures are presented in the context under specified filter performance. Finally, to verify the proposed design method, an example of self‐packaged TM‐BPF at 6 GHz with a good lower stopband and a wide upper rejection band is designed, fabricated, and measured. The measured results are in good agreement with simulated ones.
This paper at first presents the proposal and design of a filtering crossover and diplexer with two second-order filtering channels on substrate integrated waveguide (SIW) quadruple-mode resonators (QMRs) and in a respective single cavity. The proposed method has an interesting application in the overall size miniaturization design. The proposed resonator is yielded with four perturbed modes, TE103, TE104, TE201 and TE202, and featuring distinct electric field distribution, by inserting metal via-holes in the center of a rectangular SIW cavity. Next, a pair of resonances is applied to form a second-order channel filter while TE201 and TE202 modes are implemented to realize the other, thereby integrating the whole circuit in a single cavity. Besides, the transmission responses between the channels are isolated only by the perturbed via-holes. Slots are introduced in the metal surface to further increase each channel design flexibility. In this way, controllable frequencies and compact size have been well achieved. Two examples including a diplexer and crossover with two second-order channels are designed, fabricated, and measured to verify. Good agreement between simulation and measurement can be observed. INDEX TERMS Crossover, diplexer, quadruple-mode resonator (QMR), single cavity, substrate integrated waveguide (SIW).
A compact filtering crossover utilizing substrate integrated waveguide (SIW) quintuple-mode resonator (QMR) technology is proposed for the first time. Benefiting from this technology, the proposed crossover firstly breaks the status quo that SIW crossover filtering response is only concentrated in single passband, thereby extending the applications of the SIW crossovers. In design, the QMR is derived by embedding metal-via holes in the conventional SIW resonant cavity, thus to produce quintuple resonant modes featuring with specific electric distributions. Next, by dividing these modes into two groups, a triple-mode bandpass filter (BPF) channel and a single-mode dualband BPF channel are both realized. To implement two flat passband channels, there are two SIW cavities cascaded. And also, the isolation between two channels is implemented by employing the orthogonal characteristic. In this way, a crossover is implemented. The proposed design method can be a good candidate for developing SIW multi-band filtering crossovers. For verification, an example circuit has been designed, fabricated, and measured.
A miniaturized dual-mode sector patch bandpass filter using a single via-hole is presented in this article. Only a single 11.25 sector patch resonator, which is one-thirtysecond of the complete circular patch resonator, is utilized to miniaturize the filter for the first time. Without changing the size and construction of the initial patch, a simple via-hole is used to perturb the patch resonator, thus the novel dominant mode, which provides further compactness is generated. In addition, the change of viahole position is utilized to expand the bandwidth and significantly enhance the flexibility of the filter. Moreover, the proposed filter possesses two transmission zeros and it has obvious advantages of low insertion loss, compact size, and wide passband.
A stripline hybrid dual‐capacitively loaded (DCL) substrate integrated waveguide (SIW) resonator is proposed and analyzed in this letter. First, the fundamental mode (TE101) and two higher order modes (TE102 and TE201) are shifted lower through the capacitive perturbation effect. Extra Striplines are then integrated with the proposed DCL triple‐mode resonator to generate transmission zeros both below and above the passband. Subsequently, the proposed stripline hybrid DCL SIW resonator is used to design an example fourth‐order filter with three transmission zeros. A step‐by‐step design guideline is then summarized under specified filter performance. Finally, to verify the proposed design method, an example fourth‐order bandpass filter at 5.5 GHz with an improved lower rejection band is designed, fabricated, and measured. The measured results indicate that this filter has the advantages of compact size, good selectivity, and easy three‐dimensional integration.
This letter presents a compact tri‐band filter using a dual‐capacitively loaded (DCL) substrate integrated waveguide (SIW) triple‐mode resonator. The frequencies of TE101, TE102, and TE103 are shifted lower by the capacitive loading effect, which is achieved by the DCL structure. A compact tri‐band example filter is then built by using two DCL triple mode SIW resonators. Following that, seven transmission zeros are generated to improve filter selectivity by vertical coupling of two cavities. The area of the filter occupies only 0.46 λg2. The measured results demonstrate that this compact tri‐band filter has the advantages of flexible control of passbands, easy interconnection with other planar radio frequency components, making it promising for millimeter wave implementations and 3D‐integrated systems.
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