Single Substrate Integrated Waveguide Cavity Research Articles

Design of dual‐band balanced bandpass filter based on a single substrate integrated waveguide cavity

This paper proposes a dual-band balanced bandpass filter (BPF) based on a single interfered substrate integrated waveguide (SIW) cavity. The TE201, TE202, TE401, and TE402-modes are controlled by the metallic vias and divided into two groups. The first passband is made up of the affected TE201 and TE202-modes, while the second passband is made up of the disturbed TE401 and TE402-modes. In this balanced BPF design, it realizes the requested differential-mode (DM) transmission and common-mode (CM) suppression. Particularly, the bandwidths (BWs) of the two DM passbands can be efficiently controlled by only adjusting the locations of these metallic vias. A prototype dual-band balanced BPF operating at 16.71 and 22.23 GHz with BWs controllable is fabricated and measured for verification. Good accordance between simulation and measurement can be observed.

Compact triple‐band filter with adjustable passbands on one substrate integrated waveguide square resonant cavity

AbstractA new compact triple‐band bandpass filter (BPF) with adjustable passbands based on only single substrate integrated waveguide (SIW) square resonant cavity is proposed in this letter. The first six resonant modes (the perturbed TE101′ mode and TE102′ mode, the perturbed TE201′ mode and TE202′ mode, the perturbed TE301′ mode and TE302′ mode) of the SIW cavity are controlled to constitute the three corresponding passbands by elaborately introducing metallic vias in the design. The three center frequencies and passband bandwidths can be effectively adjusted by only changing the location and sizes of these perturbations. For demonstration, a prototype SIW triple‐band BPF is designed, fabricated, and tested. Measured and simulated results are in good agreement, verifying the feasibility of the design concept.

Design and Implementation of SIW Cavity-Backed Dual-Polarization Antenna Array With Dual High-Order Modes

In this communication, a novel approach for high-order modes excitation using substrate-integrated waveguide (SIW) is proposed for the implementation of a dual-polarization cavity-backed slot antenna. The antenna consists of a resonant SIW cavity with eight radiating slots and two separated SIW feeding networks. The vertically linear polarization (VLP) and horizontally linear polarization (HLP) are realized by adopting the TE430 and TE340 modes with different signal schemes. The field distributions and the surface currents of the TE430 and TE340 modes are used to analyze and illuminate the radiation mechanism. To further validate the proposed design, a $2 \times 2$ polarization-diverse SIW cavity-backed antenna array is fabricated and tested. The measured results show that the impedance bandwidths (S11 < −10 dB) for the two linear-polarization (LP) states are 10.73–10.9 GHz and 10.75–10.83 GHz, respectively, while the 3 dB axial ratio bandwidth for the right-hand circular polarization (RHCP) is 10.75–10.83 GHz. The measured peak gains of the two LP modes and CP mode are 13.4, 12.92, and 12.2 dBi, respectively. The proposed approach demonstrates an effective way of high-order modes (TE430 and TE340 modes) generation in a single SIW cavity, which has significant meaning in polarization-diversity applications.

Synthesis Method for Substrate-Integrated Waveguide Bandpass Filter With Even-Order Chebyshev Response

A synthesis method for an even-order Chebyshev bandpass filter of a substrate-integrated waveguide (SIW) is proposed in this paper. The transformation of a Chebyshev polynomial is studied and applied to achieve an equal source and load termination for an even-order filtering response. This transformed Chebyshev polynomial is used to design a millimeterwave (mmW) SIW bandpass filter through electric coupling of SIW resonators or cavities. The cascaded resonators are formed by properly etching the slots on the top metal plane of a single SIW cavity, and these slots create electric coupling as desired in a filter design. The proposed synthesis procedure of coupled-resonator bandpass filter with an even-order Chebyshev response is given and discussed here in detail. The theoretical and extracted external quality factor (QE) and coupling coefficient (K) are utilized to determine the filter circuit dimensions. Two fourth-order bandpass filters are designed at 140 GHz under a Chebyshev response using magnetic coupling and electric coupling as design examples. These two filters are used to prove the correctness of the proposed synthesis method as well as the advantages of electric coupling in mmW. In order to prove the validity, the previously proposed fourth-order filter using electric coupling is fabricated. The filter is fabricated in a single substrate layer using a low-temperature cofired ceramic technology and measured in a frequency band around 140 GHz. The measured results are in good agreement with simulated results.

RF Characterization of Magnetodielectric Material Using Cavity Perturbation Technique

Magnetodielectric (MD) materials find application in many areas of microwave engineering, and therefore, measurement of their dielectric and magnetic properties is very important. This paper presents a novel MD material characterization method using the cavity perturbation technique (CPT) with substrate-integrated waveguide (SIW) cavity resonators. Frequency dependent complex permittivity and permeability of MD material can be extracted with a single SIW cavity structure by inserting the sample material into different locations. The fundamental theory of CPT is explained and its analysis for SIW cavity is discussed. Cobalt nanoparticles are synthesized with a fluoropolymer matrix to realize the MD materials and their properties are measured in the frequency range 1–4 GHz. The effect of volume fraction and density of the synthesized MD materials on the dielectric and magnetic properties has been studied.

Design of Millimeter-Wave Bandpass Filter Using Electric Coupling of Substrate Integrated Waveguide (SIW)

A millimeter-wave (mmW) bandpass filter (BPF) using substrate integrated waveguide (SIW) is proposed in this work. A BPF with three resonators is formed by etching slots on the top metal plane of the single SIW cavity. The filter is investigated with the theory of electric coupling mechanism. The design procedure and design curves of the coupling coefficient (K) and quality factor (Q) are given and discussed here. The extracted K and Q are used to determine the filter circuit dimensions. In order to prove the validity, a SIW BPF operating at 140 GHz is fabricated in a single circuit layer using low temperature co-fired ceramic (LTCC) technology. The measured insertion loss is 1.913 dB at 140 GHz with a fractional bandwidth of 13.03%. The measured results are in good agreement with simulated results in such high frequency.

Design and Experimental Verification of Compact Frequency-Selective Surface With Quasi-Elliptic Bandpass Response

A compact frequency-selective surface (FSS) having a quasi-elliptic bandpass response is presented in this paper. This was realized by vertically cascading substrate integrated waveguide (SIW) cavities. A single SIW cavity FSS has been fully studied and approximate analytical formulas are introduced to calculate its resonant frequencies. Two different resonances can be excited by a plane wave in the single SIW cavity FSS. According to theories of the cascading cavity filter and dual-mode filter, cross coupling can be realized in cascading SIW cavity FSSs, thus a compact FSS with a quasi-elliptic bandpass response is implemented. A Ka-band sample was fabricated by a printed circuit board (PCB) process. Experiments were carried out to validate this design method. Measured results are in agreement with predicted ones. The proposed quasi-elliptic FSS presents a number of advantages, namely, high selectivity, stable performance, and much reduced volume.