Dual-mode Substrate Integrated Waveguide Cavity Research Articles

High Selectivity, Dual-Mode Substrate Integrated Waveguide Cavity Bandpass Filter Loaded Using CCSRR

In this paper, a third-order, high selectivity Substrate Integrated Waveguide (SIW) bandpass filter (BPF) loaded with Circular Complementary Split-Ring Resonator (CCSRR) is proposed for C band applications. The SIW cavity BPF comprises two stepped resonators ([Formula: see text] and [Formula: see text]) and one CSRR ([Formula: see text]) engraved on the top metal plate. Initially, the cavity loaded with stepped resonators ([Formula: see text] and [Formula: see text]) alone does not make a good selectivity on the lower out of band. Hence, the CCSRR is introduced between the stepped resonators ([Formula: see text] and [Formula: see text]) to improve the filter’s selectivity and enhance the filter’s bandwidth. The introduction of CCSRR enhances the selectivity on the lower out-of-band at 5.5[Formula: see text]GHz, and the extra pole increases the bandwidth. The metamaterial behavior of CCSRR is validated by permittivity extraction. The 3[Formula: see text]dB bandwidth of the third-order SIW filter is 840 MHz with a center frequency of 6.18[Formula: see text]GHz. The designed filter uses RTDuroid 5880 substrate of [Formula: see text] = 2.2 with a size of 28.4 × 28.4 × 0.51[Formula: see text]mm3. The proposed filter measurement and simulated results agree with each other.

C/X Dual-Band Circularly Polarized Shared-Aperture Antenna

A novel dual-band circularly polarized (CP) shared-aperture antenna is proposed in this letter. The overall structure consists of a substrate-integrated waveguide (SIW) slot antenna working in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band, which also serves as the top patch of a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> -band microstrip-like antenna. The SIW slot antenna achieves CP radiation by etching a circular slot on the top surface of a dual-mode SIW cavity. The patch antenna realizes CP radiation by loading two pairs of asymmetric shorting vias. With this design method, the proposed antenna can achieve dual-band CP operation and high aperture reuse efficiency. Besides, the feeding pin of the SIW slot antenna inserts through one of the asymmetric shorting vias, that is, the shorting vias serves as both perturbations for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> -band operation and a feeding path for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band operation. This new feeding scheme can prevent signal crosstalk between the two bands.

Balanced multiple‐layer dual‐mode substrate integrated waveguide filters with controllable finite‐transmission zeros

This paper proposes three balanced multiple-layer dual-mode substrate integrated waveguide (SIW) bandpass filters. The first balanced filter has two substrate layers, and two pairs of balanced feeding ports are located on the upper substrate layer. The lower and upper dual-mode SIW cavities are coupled by two crossed slots in the middle metal layer. The second balanced filter has two substrate layers, and two pairs of balanced feeding ports locate parallelly on the upper and lower substrate layers, respectively. The third balanced filter has three substrate layers, and two pairs of balanced feeding ports locate vertically on the upper and lower substrate layers, respectively. The proposed three balanced filters can produce three, two and one finite-transmission zeros (FTZs), respectively. Characteristics of the proposed multiple-layer SIW filters with controllable FTZs' locations are analysed in detail. For the demonstration, some design examples with the centre frequency of 7.5 GHz and bandwidth of 240 MHz are presented, and three design examples are fabricated to verify the performance of the proposed balanced filters. The measured results agree well with simulated ones.

Performance Enhancement of a Planar Slot Phased Array by Using Dual-Mode SIW Cavity and Coding Metasurface

This communication presents a planar phased array designed with an enhanced reflection bandwidth, a wide-angle scan, and a broadband low backscattering. On one hand, an improved substrate integrated waveguide (SIW) cavity-backed slot antenna which supports dual resonant modes is designed and utilized as the array element. The dual-resonance element presents the advantages of wideband reflection, wide-beam radiation, and compact size, which has the benefit for the wideband wide-angle scan of the proposed phased array. On the other hand, a coding metasurface, which consists of four specially arranged unit cells, is presented and surrounds the slot array. Based on the specially designed coding metasurface, the array gain is enhanced and a broadband scattering reduction is realized. Both simulated and experimental results indicate that the designed phased array supports a main-beam scan up to 60° and a 3 dB beam coverage up to 75° in an active reflection band of 10.1-11.6 GHz. Besides, the results also show that the radar cross section (RCS) has the reduction from 6.2 to 16.3 GHz and from 6.2 to 15.2 GHz for TM and TE polarizations, respectively.

A Class of Box-Like Bandpass Filters With Wide Stopband Based on New Dual-Mode Rectangular SIW Cavities

This article proposes a new class of box-like substrate integrated waveguide (SIW) filters with wide stopband. First, a two-pole doublet bandpass filter with one finite-transmission zero (FTZ) is proposed using a new planar dual-mode rectangular SIW cavity, which is realized by TE201 and TE103 modes. TE102, TE202, and TE104 modes are suppressed intrinsically by arranging feeding lines at the horizontal centerline of the dual-mode SIW cavity. Then, a four-pole box-section filter with one FTZ is proposed using one dual-mode and two single-mode rectangular SIW cavities, and the two single-mode cavities have different width-length ratios to further improve the stopband performance. To further improve the cutoff skirt, a new design method for five-pole quasi-elliptic SIW filter is proposed, which is achieved by the four-pole filter loaded by one single-mode SIW cavity. Some design examples with the center frequency of 10 GHz are presented to verify the performance of the proposed dual-mode SIW filters and the design method.

Compact, Vertically Integrated Duplex Filtenna With Common Feeding and Radiating SIW Cavities

In this communication, a compact vertically integrated full-duplex filtenna is developed by using common feeding and radiating substrate integrated waveguide (SIW) cavities. A rectangular dual-mode SIW cavity, operating at its two orthogonal TE120 and TE210 modes, is first employed as the common feeding cavity to realize two passbands. And then, a common radiating square slot-loaded SIW cavity is vertically integrated with the common feeding cavity so as to enhance the operational bandwidth and improve the frequency selectivity for both two passbands. Two metallic posts are utilized to achieve the desired coupling strength between the feeding and radiating cavities for the two passbands, respectively. By properly arranging the locations of two input ports and coupling regions, high isolation between the two input ports is realized. The detailed design process based on the coupling matrix is presented. To verify the proposed concept, a prototype is fabricated and measured. The measurement results agree well with the simulated values, showing the maximum broadside realized gains of 4.36 and 4.83 dBi, and the impedance bandwidths of 3.2% (4.03–4.16 GHz) and 3.9% (4.81–5 GHz) for the lower and upper passbands, respectively. The proposed antenna also exhibits good performance in terms of port isolation, flat in-band gain response, and out-of-band frequency selectivity.

Compact balanced bandpass filters based on multilayer dual-mode substrate integrated waveguide cavities

To design size-reduced balanced bandpass filters (BPFs) with high selectivity, two new multilayer dual-mode substrate integrated waveguide (SIW) balanced BPFs are proposed. Firstly, the characteristic of dual-mode SIW cavity is analyzed in detail. Then, a balanced SIW BPF with balanced input/output (IO) ports locating on the upper dual-mode SIW cavity is proposed, and the lower dual-mode SIW cavity is coupled to the upper one using two crossed slots. Three transmission zeros (TZs) can be produced at any locations. A balanced SIW BPF with balanced IO ports locating on the upper and lower dual-mode cavities respectively is also proposed, and the two cavities are coupled by a slot. Two symmetrical TZs can be produced. Based on the proposed structures, two filters with center frequency of 10 GHz are designed, fabricated and measured. The measured results agree well with the simulated ones, which indicates the feasibility of the proposed multilayer dual-mode SIW balanced BPFs with compact size and high selectivity.

A Low Pulling Effect Self-Isolated Harmonic Active Radiator for Millimeter-Wave Internet-of-Things Applications

A low pulling effect self-isolated harmonic active radiator operating around 28 GHz is proposed, investigated, and demonstrated in this article. Thanks to the inherent self-isolation property of a feedback loop of the proposed active radiator, a superiority of pulling effect mitigation, harmonic output, and simple structure is achieved. As part of the loop, a partially air-filled dual-mode substrate integrated waveguide cavity with a dielectric-loaded broadside slot is designed to realize the functions of resonators, harmonic diplexers, and antennas concurrently. The radiator oscillates at a fundamental frequency which is set by the first mode of the cavity resonator, and the generated second harmonic signal is extracted and radiated by the diplexer and antenna functions, respectively. Self-isolation is achieved because a pulling signal is attenuated by the synergetic effect of the reverse isolation and harmonic separation of the loop amplifier and diplexer, respectively. Measured results of a fabricated prototype show a maximum equivalent isotropic radiated power of 15 dBm at 28.15 GHz and a phase noise of −108 dBc/Hz at 1 MHz offset. Load pulling and injection pulling are reduced by a factor of 10 and 17, respectively, compared with an active radiator transmitting a fundamental signal around 28 GHz. Such a robust and compactly integrated structure is a good candidate for low-cost millimeter-wave Internet-of-Things applications in connection with identification, sensing, tracking, and communication.

Multi‐layered dual‐mode substrate integrated waveguide bandpass filter with input and output ports located on same substrate layer

This study reports a multi-layered dual-mode substrate integrated waveguide (SIW) bandpass filter (BPF), in which the input and output ports are located on the same substrate layer (i.e. the upper one). The dual-mode SIW cavity in the lower substrate layer is coupled to the upper dual-mode SIW cavity by two crossed slots, which can independently control the inter-couplings. The proposed filter can be modelled by a dual-extended doublet coupling scheme with considering bypass couplings between source and load. Based on the proposed structure, single- and dual-band filtering responses with four controllable finite-transmission zeros (FTZs) are realised and analysed. For the demonstration, a single-band filter and a dual-band filter were fabricated and measured. The measured results agree well with simulated ones.

Triple‐mode bandpass filter

triple‐mode bandpass filter

Balanced dual‐mode SIW filter

This Letter proposes a balanced dual-mode substrate integrated waveguide (SIW) filter for the first time. Based on dual-mode square SIW cavities, perturbation vias, and balanced ports, the quasi-elliptic differential mode response with improved selectivity as well as high-performance common mode suppression can be obtained conveniently. Resonator number decrease and compact size can also be available.

Circularly Polarized Antennas Inspired by Dual-Mode SIW Cavities

This paper presents a detailed study on a family of circularly polarized (CP) antennas inspired by the dual-mode substrate integrated waveguide (SIW) cavities. The related design methodology has been proposed and summarized for the first time. The field distribution for dual-mode SIW cavities (using TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> , TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">103</sub> modes) are first analyzed. Based on the current flow of the orthogonal modes, slot cuts are incorporated on the top surface considering both the phase and current magnitude, which leads to optimal boresight CP radiation. All the feasible slot combining configurations which are able to generate CP radiation for the dual-mode cavities are summarized and characterized. For experimental verification, four low-profile, low-cost and high- efficiency CP antennas using the dual-mode cavities are proposed, analyzed and implemented, including two CP antennas based on the degenerate TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> /TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> half-mode-like resonators, and a CP antenna as well as its 2-element array using the degenerate TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">103</sub> / TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">201</sub> dual-mode cavity. The measured and simulated results are in excellent agreement. Useful design guidelines are provided. These antennas show a measured bandwidth varying from 2.0 % to 4.1 % and a peak gain ranging from 7.0 dBic to 9.4 dBic, respectively. They demonstrate good CP performance and high radiation efficiency which is better than 88 % in simulation. They offer attractive features including interesting working principle, easy implementation, low-cost, and non-sensitivity to tolerance, appearing as good candidates for high-frequency directive antenna application.

Synthesis Design of SIW Multiband Bandpass Filters Based on Dual-Mode Resonances and Split-Type Dual- and Triple-Band Responses

A synthesis design method for substrate-integrated waveguide (SIW) multiband bandpass filters (BPFs) with flexible frequency and bandwidth allocations is presented by incorporating SIW dual-mode resonances with split-type dual- and triple-band symmetrical frequency responses. By different combinations of the split-type dual- or triple-band responses for two virtual wide passbands dominated by TE101 and TE201 modes in SIW rectangular cavities, SIW tri-/ quad-/quint-/sext-band BPFs with improved band assignments can all theoretically be implemented. In addition, by introducing our previously proposed dual-mode coupling controlling technique, the bandwidths of the two virtual wide passbands can also be allocated flexibly. Three experimental prototypes, including a quad-band BPF based on four dual-mode SIW cavities, a quad-band and quint-band BPFs based on two dual-mode SIW cavities coupled with multiple single-mode ones, are synthesized, designed, fabricated, and tested to demonstrate and validate the collaborative design concept.

Planar integrated substrate integrated waveguide circularly polarized filtering antenna

A new design of substrate integrated waveguide (SIW) circularly-polarized (CP) filtering antenna is presented, which is based on dual-mode (TE102 and TE201) cavities. The satisfying filtering performance of the antenna is realized by a coupled-resonator circuit of two dual-mode SIW cavities. And the radiating element of the antenna is a cavity-backed CP slot antenna which is formed by a nonuniform ring slot integrated with the back cavity. To demonstrate the idea, a prototype antenna operating at X band is designed, fabricated, and measured. Measured results show that the 10-dB impedance bandwidth is 4.2% (from 11.6 to 12.1 GHz), the 3-dB axial-ratio (AR) bandwidth is 4%, and the gain is 5.6 dBi at the center frequency of 11.8 GHz.

A Millimeter-Wave Filtering Monopulse Antenna Array Based on Substrate Integrated Waveguide Technology

A millimeter-wave filtering monopulse antenna array based on substrate integrated waveguide (SIW) technology is proposed, manufactured, and tested in this communication. The proposed antenna array consists of a filter, a monopulse comparator, a feed network, and four antennas. A square dual-mode SIW cavity is designed to realize the monopulse comparator, in which internal coupling slots are located at its diagonal lines for the purpose of meeting the internal coupling coefficiencies in both sum and difference channels. Then, a four-output filter including the monopulse comparator is synthesized efficiently by modifying the coupling matrix of a single-ended filter. Finally, each SIW resonator coupled with those four outputs of the filter is replaced by a cavity-backed slot antenna so as to form the proposed filtering antenna array. A prototype is demonstrated at Ka band with a center frequency of 29.25 GHz and fractional bandwidth of 1.2%. Our measurement shows that, for the H-plane, the sidelobe levels of the sum pattern are less than -15 dB and the null depths of the difference pattern are less than -28 dB. The maximum measured gain of the sum beam at the center operating frequency is 8.1 dBi.

SIW magic‐T with bandpass response

A novel magic-T with bandpass filtering response using substrate integrated waveguide (SIW) technology is presented. The basic design concept is based on properly locating the two power-division ports in a dual-mode circular SIW cavity, whose field distributions are even or odd symmetric. Not only in-phase and out-of-phase operations can be achieved in the magic-T, but also filtering responses for the two operations can be obtained. This magic-T is fabricated in a single-layer PCB and measured results show that it is centred at 9 GHz with 70 MHz 3 dB bandwidth. Good measured performance of balance for magnitude (±0.35 dB) as well as phase (0°–5°) is also obtained within the passband.

Design of Dual-Mode Substrate Integrated Waveguide Band-Pass Filters

Three dual-mode band-pass filters are presented in the present paper. The first filter is realized by dual-mode substrate integrated waveguide (SIW) cavity; the second is based on the integration of SIW cavity with electromagnetic band gap (EBG); and the third is based on the integration of SIW cavity with complementary split ring resonator (CSRR). The dual-mode SIW cavity is designed to have a fractional bandwidth of 4.95% at the midband frequency of 9.08 GHz; the proposed EBG-SIW resonator operates at 9.12 GHz with a bandwidth of 4.38% and the CSRR-SIW resonator operates at 8.66 GHz with a bandwidth of 2.54%. The proposed filters have the high Q-factors and generate a transmission zero in upper stopband, and these by the use of Rogers RT/duriod 5880 (tm).

Design of a Bandwidth-Enhanced Polarization Rotating Frequency Selective Surface

An approach for the bandwidth enhancement of a polarization rotating frequency selective surface (FSS) based on the substrate integrated waveguide (SIW) technology is proposed in this communication. Compared with the previously reported polarization rotating FSS, the passband bandwidth of the proposed FSS is enhanced from 4.6% to 7.2% by introducing a triple-mode SIW cavity resonator as the periodic element. Meanwhile, better frequency response selectivity of filtering performance is achieved. The proposed FSS is made up of a periodic array of the novel triple-mode SIW cavity resonators with two orthogonal slots on the front and back surfaces for polarization rotation. The triple-mode SIW cavity resonator is achieved by placing a metallic via at the center of a dual-mode SIW cavity resonator. Bandwidth enhancement of the FSS is achieved by simultaneously exciting and properly merging together these three modes in the SIW cavity resonator. A prototype designed at Ka-band was fabricated and measured. Good agreement between the measurement and simulation results has been achieved.

Symmetric dual-mode filter based on substrate integrated waveguide (SIW)

A planar four-pole dual-mode filter with symmetric transmission response based on substrate integrated waveguide (SIW) is proposed. The filter centered at 10 GHz, consisting of two TE102–TE201 dual-mode SIW cavities, is implemented in a single layer substrate by PCB process. A linear microstrip taper is used to implement the transition between 50 Ω microstrip and SIW. The measured results are in agreement with simulated results.

Substrate integrated waveguide (SIW) asymmetric dual-mode filter and diplexer

Substrate integrated waveguide (SIW) can be used to implement high Q waveguide components with the same easy and low-cost fabrication process as planar circuits. In this paper two inline three-pole dual-mode filters with asymmetric transmission response based on SIW are presented. These two filters, consisting of a TE102-TE301 dual-mode SIW cavity and a TE101 mode SIW cavity, are centred at around 10 GHz with a transmission zero on the left of the passband and the right of the passband, respectively. Based on the two kinds of three-pole deal-mode filters, a diplexer with isolation better than 35 dB is developed. A linear microstrip taper is used to implement the transition between microstrip and SIW. The measured results agree with simulated results.