Dual-mode Substrate Integrated Waveguide Research Articles

Millimeter-Wave Monopulse Filtenna Array with Directive Dielectric Resonators

This paper presents a new millimeter-wave monopulse dielectric resonator (DR) filtering antenna (filtenna) array based on substrate-integrated waveguide (SIW) technology. The monopulse comparator realized by a square dual-mode (<i>TE</i><sub>102</sub> and <i>TE</i><sub>201</sub>) SIW feed cavity uses diagonal irises, of which couplings between the feed and next-stage cavities lead to almost identical filter responses for the sum and difference channels with compact size and a planar single-substrate structure. Both dielectric resonator antennas (DRAs) adopting <i>HEM</i><sub>133</sub> mode for enhanced directivity are implemented with two filters based on SIW. The DR acts as the last resonator and the radiator in the filtenna. The prototype is designed at the Ka-band with a center frequency of 27.65 GHz and an operation bandwidth of 700 MHz. The measurement shows a 15-dB fractional bandwidth of 2.36%, a gain of 10.84 dBi for the sum channel, and a null depth of -15.6 dB for the difference channel.

Compact or Wide-Stopband SIW Diplexers With High Intrinsic Isolations Based on Orthogonal Dual Modes

This brief proposes two miniaturized substrate integrated waveguide (SIW) diplexers with wide stopband and high isolation based on orthogonal dual-mode technique. With the orthogonal dual-mode SIW junction-resonators to eliminate the traditional T-junctions, significant circuit miniaturization and the inter-channel isolations can be achieved for SIW diplexers. Additionally, the fractional bandwidth (FBW) diagrams are utilized to identify the feasible FBWs in both passbands effortlessly. To verify the developed method, two types of SIW diplexers centered at 12 and 14 GHz are synthesized and fabricated utilizing a single layer printed circuit board technology. The performances of both diplexers are demonstrated by the measured and simulated results.

Dual-Polarized Patch Antenna Excited Concurrently by a Dual-Mode Substrate Integrated Waveguide

In this work, we propose and demonstrate an integrated dual linearly polarized cavity-backed patch antenna, which is excited by a concurrent dual-mode substrate integrated waveguide (SIW) structure. For the first time, we have exploited the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">20</sub> modes of a traveling wave in a dual-mode SIW configuration to excite the horizontal and vertical polarizations of the patch antenna. The proposed methodology yields a low-profile structure with a high interport isolation thanks to the inherent symmetry of the structure. Measurement results indicate an isolation performing better than 42 dB over a 600 MHz impedance bandwidth of the antenna. Moreover, a methodology is developed to implement transitions from the dual-mode SIW to the two different TEM transmission lines for separate but concurrent excitations of the device. Detailed field and impedance analyses are presented to explain the operation principle of the proposed antenna, which are supported by an excellent agreement between the obtained measurement and simulation results.

Miniaturized Diplexers With Large Frequency Ratios Based on Common Half-Mode Dual-Mode SIW Junction-Cavities

Miniaturized substrate integrated waveguide (SIW) diplexers with widely separated channel passbands using common half-mode dual-mode SIW junction-cavities are presented and developed for 5G sub-6 GHz communications and wireless systems. With this kind of half-mode dual-mode junction-cavities to eliminate the conventional T-junctions and also to produce one transmission pole in each channel passband, significant circuit miniaturization can be achieved for SIW diplexers. Additionally, by exploiting the first dual modes in the half-mode SIW junction-cavities, flexibly allocated fractional bandwidths (FBWs) for the two channels can be realized through FBW design graphs, large frequency ratios can also be accommodated, which is difficult to implement using the whole-mode SIW cavity scheme due to spurious problems. Two compact SIW diplexers with large frequency ratios are synthesized, designed, fabricated, and measured for demonstration, including a third-order direct-coupled prototype centered at 3.5 and 5.0 GHz with a frequency ratio of 1.43 based on the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub> /TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">301</sub> half-mode dual-mode junction-cavity and a fourth-order cross-coupled prototype centered at 3.5 and 5.5 GHz with a frequency ratio of 1.57 based on the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub> /TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">102</sub> half-mode dual-mode junction-cavity.

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.

Compact Dual-Band Dual-Mode SIW Balanced BPF With Intrinsic Common-Mode Suppression

In this letter, a compact dual-band dual-mode substrate integrated waveguide (SIW) balanced band-pass filter (BPF) with intrinsic common-mode (CM) suppression is designed by using a single perturbed SIW circular cavity. The vias and slot perturbations are introduced to tune the resonant modes TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">010</sub> , TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">110</sub> (a pair of degenerate modes), and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">210</sub> of a circular cavity. Thus, they can be used to form two differential-mode (DM) passbands with independently adjustable center frequencies and bandwidths. The SIW can be seen as a natural balun with intrinsic CM suppression. Furthermore, the planar differential excitation structure is designed to excite the perturbed SIW cavity. The CM noise cannot excite SIW cavity due to the characteristics of hybrid electromagnetic boundary. Finally, a compact dual-band dual-mode SIW balanced BPF at 8 and 10 GHz is designed and fabricated, and the measured results show good agreement with the simulated ones.

Pin-Loaded Patch Antenna Fed With a Dual-Mode SIW Resonator for Bandwidth Enhancement and Stable High Gain

A pin-loaded patch antenna fed with a dual-mode substrate-integrated waveguide (SIW) resonator is proposed in this letter for enhanced bandwidth and stable high gain. The loading effect of shorting pins on quality factor of the radiator is investigated with characteristic mode analysis at first. As such, the pin location can be properly selected to enhance gain with the least negative effect on bandwidth. A SIW resonator operating in TE110 and TE120 modes is introduced to feed the patch through aperture coupling. The dual modes of SIW resonator increase the resonant order of the antenna with compact size, which significantly widens the bandwidth. Moreover, the undesired high-order mode is well suppressed with the proposed feeding scheme, which further contributes to steady radiation performance. Simulated and measured results demonstrate that the proposed patch antenna has obtained an enhanced bandwidth of 22% and stable high gain up to 11.9 dBi simultaneously.

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 Millimeter-Wave Endfire Dual-Polarized Antenna Array for Low-Cost Multibeam Applications

A compact multibeam endfire dual-polarized antenna array for low-cost millimeter-wave (mmWave) applications is proposed in this letter. Multimode substrate-integrated waveguide (SIW) section with interactions is applied as the basic beamformer. The dual-mode SIW is used in the beamforming network to support dual-polarization application without occupying an extra area. The printed dipole antenna with integrated balun and the open-ended SIW antenna with metallic strips are integrated to realize an endfire dual-polarized antenna element. Based on this endfire antenna element, a multibeam dual-polarized antenna array is developed. The proposed antenna array includes a four-element antenna array, an SIW beamforming network, and transitions. Additional air gaps between antenna elements are designed for mutual coupling reduction. The fabricated multibeam endfire dual-polarized antenna array achieves an impedance bandwidth of 11.3%, and the overlapped 3 dB beamwidth of the four generated beams in two polarizations are able to cover a wide range between ± 41°. The proposed low-cost multibeam antenna array can be a good candidate for 5G mmWave wireless applications.

High Isolation Substrate Integrated Waveguide Diplexer With Flexible Transmission Zeros

This letter presents a high isolation substrate integrated waveguide (SIW) diplexer using dual-mode resonators. Each dual-mode SIW resonator can generate one transmission pole (TP) and one transmission zero (TZ) for the channel filter. The frequencies of the TZs can be easily controlled by the perturbation vias. One channel filter’s two TZs’ frequencies are designed to cover the other channel filter’s passband. Thus, high isolation performance is achieved. The proposed diplexer is designed and fabricated with lower and upper channels centered at 8.04 and 9.07 GHz, respectively. Simulated and measured results are in good agreement for the two channels with better than 49/53-dB channel isolation.

Multilayer Dual-Mode Balanced SIW Filter Utilizing PEC–PMC Characteristic for Common-Mode Suppression

In this letter, a multilayer balanced substrate-integrated waveguide (SIW) bandpass filter (BPF) using the TE102 and TE201 modes is designed with an aperture etched on the common ground between two stacked SIWs. Under common-mode (CM) operation, the aperture is a perfect magnetic conductor (PMC). When the height is less than λ g /4, the space between the perfect electric conductor (PEC) and the PMC cannot transmit the electromagnetic wave, so the structure can effectively cutoff the CM noise in a wide frequency range. Under differential-mode (DM) operation, the aperture is the PEC and has less effect on the DM frequency responses by properly selecting the location and size. Two transmission zeros near the passband edges can be generated to improve the selectivity. Finally, a compact dual-mode balanced SIW BPF with high selectivity and CM suppression has been designed and fabricated, and the measured results show good agreement with the simulated ones.

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.

High-Selectivity Tunable Filters With Dual-Mode SIW Resonators in an L-Shaped Coupling Scheme

This article reports the design of high-selectivity tunable bandpass filters with constant absolute bandwidth (CABW) using dual-mode (DM) substrate-integrated-waveguide (SIW) resonators. The even and odd modes are coupled to the source and load using an L-shaped coupling scheme instead of the conventional doublet scheme, and thus, each mode produces either one reflection zero or one transmission zero (TZ). Each resonator has one contactless tuner to change the frequencies of both modes simultaneously, and a controllable separation between the two modes can be obtained over the whole tuning range (TR). The proposed resonator is utilized as the building block in four prototype filters with different TZ locations. The first filter is in a principle back-to-back topology, and it distributes TZs on both sides of the passband and has a CABW across the entire TR. The rest three further explore techniques to improve the out-of-band selectivity, i.e., introducing source/load coupling to increase the reject level and relocating the TZs on one side of the passband to build a spectrum with high rejection. All filters are based on two DM SIW resonators with only two tuners. Compared to state-of-the-art works, the proposed filters offer a wide constant-BW TR, low insertion loss, high selectivity, and good nonlinear performance.

High-isolation diplexer based on dual-mode substrate integrated waveguide resonator

AbstractA high-isolation diplexer based on a dual-mode substrate integrated waveguide (SIW) resonator is proposed in this paper. Based on the theory of the dual-mode resonator, the miniaturized diplexers are designed by using the SIW dual-mode resonators. The superior isolation of the diplexers is obtained because the two operating modes of the dual-mode SIW resonators are not directly coupled and there is no interference with each other. In order to further improve the isolation of the circuit, the number of the order of the diplexer is added. Equivalent circuits are given to analyze and design the dual-mode high-isolation diplexers. Detailed analyses are given according to the equivalent circuits. The dual-mode third-order and fourth-order diplexers are designed and fabricated. The measured results agree well with the simulated ones. The total sizes of the fabricated third-order and fourth-order diplexers are 1.78λg × 2.64λg and 1.79λg × 3.63λg, respectively.

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

Substrate Integrated Waveguide Bandpass Filters in Box-Like Topology With Bypass and Direct Couplings in Diagonal Cross-Coupling Path

Substrate integrated waveguide (SIW) bandpass filters in box-like topology based on combining single- and dual-mode cavities are presented. Two coupled TE101-mode-based cavities are coupled to one square-shaped dual-mode (modes TE102 and TE201) cavity to realize the box-like coupling scheme in which bypass and direct couplings can provide the diagonal cross-coupling path. Based on the characteristics of dual-mode SIW and multiple energy flow paths, the superior design flexibility in terms of TZ positioning has been realized and demonstrated. Finally, two asymmetrical response SIW filters with two lower TZs, a quasi-elliptic SIW filter with three TZs and a filter with linear-phase response are simulated, fabricated, and measured to demonstrate and verify the proposed structure.