Substrate Integrated Waveguide Resonator Research Articles

Wide Stopband Substrate Integrated Waveguide Filter Implemented by Orthogonal Ports’ Offset

Ideally, the orthogonal port can be effective to eliminate the TE102/TE201 spurious passband of a fundamental substrate integrated waveguide (SIW) filter using the orthogonality. However, it was not feasible in practical applications because the orthogonality of TE102/TE201 is deteriorated by the orthogonal port. Here, we propose an approach to repair the orthogonality which makes the practical orthogonal port work as the ideal one and thereby avoid the TE102/TE201 spurious passband in an SIW filter. The repair is achieved using ports’ offset almost without affecting the fundamental passband. A guideline of using the proposed technique to design a wide stopband filter based on square SIW resonators is provided. Four SIW filters with three, four, five, and six resonators, respectively, are then experimented. The measured results agree with the expectations well. An empirical equation is finally given to initialize the critical ports’ offset to facilitate the design. Compared with counterparts, the proposed technique uses a much simpler design, obtains better performance, and can be more easily implemented in practical applications.

A Common-Mode Noise Suppression Filter for Gigahertz Differential Signals Based on Substrate Integrated Waveguide Resonators

A common-mode noise suppression filter for microstrip differential lines based on substrate integrated waveguide resonator (SIWR) is proposed in this article. The proposed common-mode filter (CMF) consists of cascaded SIWR units with different size. The equivalent characteristic impedance circuit model of the proposed CMF is given to predict the common-mode suppression characteristics by introducing the spectral domain approach (SDA). Simulated results show that the common-mode noise is decreased more than 35 dB from 4.5 GHz to 11.4 GHz, and −30 dB rejection band is obtained in the frequency band of 4.3-15 GHz. Moreover, the insertion loss and the group delay in the frequency domain show that there is little degradation for differential signals. In the time domain, 86.5% amplitude suppression of common-mode noise is achieved. In addition, the eye diagrams in the time domain are investigated to explain the effectiveness of the proposed CMF and indicate that the CMF can maintain the differential signal integrity. The prototype is fabricated to verify the validity of the proposed structure, and the measurement results show good agreement with the simulation results.

High‐selective triple‐mode SIW bandpass filter using higher‐order resonant modes

A novel high-selective triple-mode substrate integrated waveguide (SIW) bandpass filter using higher-order resonant modes is proposed in this Letter. The new triple-mode SIW resonator is realised by the second degenerate dual modes TM 210 and one perturbed higher-order mode TM 020 in a circular SIW cavity. The resonance of TM 020 mode can be independently moved to that of dual modes TM 210 by changing the size of a floating circular patch. The proposed triple-mode SIW filter can produce three finite-transmission zeros (FTZs), which can also be controlled well by the angle between two feeding lines. For the demonstration, a triple-mode SIW filter with the centre frequency of 13.5 GHz was designed, fabricated and measured. The proposed triple-mode circular SIW filter has the merits of the high-quality factor, high selectivity and controllable bandwidth as well as FTZs.

Practical Design and Implementation Method for Asymmetric-Response Post-Loaded Substrate-Integrated Waveguide Filters

This paper presents a practical method for implementing a post-loaded substrate-integrated waveguide (SIW) filter producing an asymmetric response with a pair of near-band transmission zeros. More specifically, we present a practical frequency-dependent coupling structure for post-loaded SIW resonators for implementing an asymmetric response. By virtue of the proposed coupling design methods, the roll-offs in the upper and lower stopbands can be readily controlled to be different from each other. In other words, the roll-off in a stopband can be made to be steeper than the one in the other stopband by means of using the proposed design method for coupling structure. More importantly, we propose a useful approach to swap the two stopband responses of an asymmetric-response filter. In other word, this paper shows a practical method to laterally reverse an asymmetric response. For demonstration, 1 symmetric-response and 2 asymmetric-response fourth-order SIW filters have been designed using the presented frequency-dependent coupling structures.

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.

Highly Sensitive Air-Filled Substrate Integrated Waveguide Resonator Integrated Wireless Passive Slot-Antenna for Confined Environmental Detection

In this paper, highly sensitive air-filled substrate integrated waveguide (SIW) resonators integrated wireless passive slot-antenna are designed and fabricated for confined environmental detection. The models of SIW sensors were established by using the software of HFSS to optimize the performance of the sensor for the 802.11 WLAN application. Due to the symmetry and the ideal-wall characteristic of the SIW, the SIW sensor can be designed into a half-mode substrate integrated waveguide (HMSIW) to reduce the size of the sensor. The SIW and HMSIW sensor were fabricated and measured experimentally. The sensitivities of HMSIW sensor for humidity detection without humidity sensitivity materials using the dielectric perturbation method were 187.67 kHz/%RH and 0.233 dB/%RH and 211.5 kHz/%RH and 0.33 dB/%RH for SIW sensor. Meanwhile, the SIW sensor can also realize the detection of ammonia filled with polyaniline material into the air-filled hole array of sensor. The slot-antenna integrated wireless passive air-filled SIW resonators with the low-cost advantage provide a new method for the detection of confined environments.

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.

In‐line ports feeding substrate integrated waveguide resonator with higher order modes suppression

In-line ports are usually used to feed substrate integrated waveguide (SIW) resonator in an in-line transmission circuit. However, the higher order mode TE 102 is excited as well as the fundamental mode TE 101 thereby deteriorating the selectivity. Here the authors present a method to remove the selectivity deterioration. By additionally introducing TE 201 , the TE 102 and the TE 201 can be counteracted with each other by taking advantage of their out-phase out-coupling, and then both modes are suppressed well in a SIW resonator feeding with in-line ports. Two prototypes based on square and rectangle cavity are fabricated, respectively and measured to verify the proposed technique. The results agree with the expectation well. It shows the potential to be implemented in the in-line transmission circuit with SIW resonator.

Multilayer SIW Dual-Band Filters with Independent Band Characteristics and High Selectivity

Abstract This work presents an approach to developing dual-mode dual-band substrate integrated waveguide (SIW) bandpass filter based on multilayer process. TE102/TE201 and TE101/TE102 modes are used to feature the two passbands, respectively. To begin with, large range of band location ratios are decided by the effective dimension of the SIW resonator. With reference to the field distribution, independent coupling schemes of the dual-modes are then realized by slots or circular apertures etched on the middle metal layer. It allows to not only introduce a large design freedom of bandwidth but also keep compactness. Finally, source-load and mixed couplings are deployed to produce transmission zeros around the passband in providing a sharp selectivity in the two filters, respectively. The details to independently control the center frequencies and bandwidth of two passbands are also presented. A two-order double-layered and a triple-layered SIW dual-band bandpass filter are prototyped to evaluate the proposed design approach, respectively. Results show a good agreement between simulations and measurements. The proposed filter exhibits flexible design freedom, high selectivity as well as good out-of-band rejection.

Design and Development of Low-Profile Multi-Band Antenna Fed by SIW Cavity Resonator Using Twin Apertures

AbstractA novel design of compact, linearly polarized and low-profile planar antenna which is electrified by Substrate Integrated Waveguide (SIW) resonator has been developed for multi-band applications of X-band spectrum. Radiating patch has been excited through two closely spaced longitudinal apertures of identical length but non-identical width, incorporated in SIW resonator. These apertures are responsible for multiple operating bands. The achieved fractional bandwidths are 1.29 %, 0.49 % and 1.60 % having resonant frequencies at 10.07 GHz, 10.85 GHz and 11.82 GHz respectively for |S11| ≤ -10 dB. The measured peak gain for first, second and third operating band is 6.54 dB, 6.86 dB and 7.68 dB respectively. The proposed antenna is a highly selective antenna for various applications of X-band microwave spectrum. This band has been particularly selected for military communication because it provides a trade-off between the characteristics (i. e. interference and rain resilience, data rates and remote coverage) of different frequency bands which are particularly suited to the needs of military users. It is very much suitable for secure communication i. e. to deny unauthorized access to sensitive unclassified information and prevent disruption of telecommunication. A comparative analysis of antenna’s parameters has been examined by Ansys HFSS and results are verified through experimental outcomes.

Compact dual‐band filter using interleaved folded half‐mode substrate integrated waveguide resonator

A multi-layer interleaved folded half-mode substrate integrated waveguide (HMSIW) dual-band filter is proposed. The TE 101 and TE 102 mode of the HMSIW resonators form dual-band response by vertical coupling, and the bandwidth of the two passbands can be independently designed by adjusting the coupling apertures. Moreover, three transmission zeros (TZs) are obtained to improve out-of-band rejection, and the TZs can be flexibly designed below or above the passband. By vertically superimposing the HMSIW cavity, the HMSIW filter can be extended to multi-pole dual-band filters. A dual-band filter with centre frequency of 3.05 and 4.7 GHz was fabricated and measured to verify the proposed method. The simulated and measured results are in good agreement.

Dual-Frequency Miniaturized Substrate Integrated Waveguide Quarter-Mode Cavity-Backed Antenna Based on Minkowski Fractal Gap with Orthogonal Polarization Radiation Characteristics

A novel quarter-mode substrate integrated waveguide miniaturized cavity-backed antenna loading Minkowski fractal gap is presented in this paper. Firstly, the resonant frequency of the rectangular substrate integrated waveguide resonator is reduced by etching the fractal gap in the resonator to achieve miniaturization. In addition, because of the symmetry of electric field distribution in second and third order resonant modes, the cavity can be segmented into a quarter-mode and the other order resonance modes with asymmetric electric field distribution can be suppressed according to the cavity model theory. Hence, the cavity size is further reduced. The dimension of designed antenna is 0.26λ0×0.26λ0 (λ0 is the wavelength in free space; in this paper, the corresponding wavelength is 3.6 GHz). Moreover, the orthogonal polarization of the proposed antenna in two frequency bands is achieved because the electric field is orthogonal in second and third order resonant modes. This dual-frequency orthogonal polarization characteristic enables antenna to communicate in two working bands and has good channel isolation. The simulated and measured results are consistent. The antenna gain is 4.67dBi and 3.4dBi, respectively, at 3.7GHz and 4.6GHz.

SIW resonator fed horn mounted compact DRA with enhanced gain for multiband applications

AbstractA novel design of compact and light-weight horn mounted cylindrical dielectric resonator antenna (CDRA) fed by substrate integrated waveguide (SIW) resonator has been investigated for high gain and multiband applications. SIW resonator contains two closely spaced longitudinal slots of equal length and unequal width to excite the CDRA. These slots are responsible for introducing triple resonating bands. The excited mode in dielectric resonator by longitudinal slots is EH11δ mode. The achieved impedance bandwidths are 65, 180, and 240 MHz at resonant frequencies 9.78, 10.58, and 11.84 GHz, respectively, for |S11| <−10 dB. Copper-taped horn enhances the gain of antenna more than 2 dB for all resonating bands. The measured peak value of gain is 9.3 dBi at ~11.84 GHz.

A method for single‐band and multiband filters design based on right trapezoid half‐mode substrate integrated waveguide

AbstractIn this article, a novel right trapezoid half‐mode substrate integrated waveguide resonator (RTHMSIWR) is firstly proposed. Based on it, a simple filter design method is presented. By controlling the ratio of the upside length to height of RTHMSIWR, the electric field distribution becomes regular and makes the resonant mode easy to generate the passband response, correspondingly. The fundamental and higher‐order modes are available to realize single‐band or multiband responses as the ratio changes, which provides a flexible choice on band allocation. For verification, a tri‐band bandpass filter (BPF) with source‐load coupling is designed. To further achieve a better rejection between the first and second passbands, a pair of complementary split‐ring resonators (CSRRs) is introduced. Total seven transmission zeros (TZs) are produced to improve the out‐band selectivity. The measured results agree well with the simulated ones.

A Single-Layer SIW Slots Array Monopulse Antenna Excited by a Dual-Mode Resonator

The conventional monopulse comparator, which commonly consists of a power divider, a standard 3dB-coupler and a 90-degree phase shifter, occupies a significantly large area of the antenna aperture. This results in a low efficiency. In order to improve the antenna's aperture efficiency and keep a planar single-layer structure simultaneously, a substrate integrated waveguide (SIW) slots array monopulse antenna excited only by a square dual-mode (TE120 and TE210) SIW resonator is proposed, fabricated and measured in this communication. The sum and difference beams are obtained when the feeding cavity operates at two high-order modes, respectively. The needless of complex feeding network reduces the antenna's structure complexity and improves its aperture efficiency. The aperture efficiency of the antenna can reach 42%. Besides, the sum and difference ports have good isolation due to the orthogonality between the two modes. The proposed antenna obtains a 100 MHz impedance bandwidth, determined by the reflection coefficient less than -10 dB. The measured gain of the sum pattern is 11.9 dBi at 10 GHz, while the null depth of the difference pattern is lower than -27 dB.

Advanced Filtering Solutions in Coaxial SIW Technology Based on Singlets, Cascaded Singlets, and Doublets

The use of singlets, cascaded singlets, and doublets in a coaxial substrate integrated waveguide (SIW) technology is proposed in this paper, with the aim of implementing low-loss filters with very compact size and highly selective symmetric, asymmetric as well as dual-band responses. Singlets based on coaxial SIW resonator structures with source-load coupling are presented and studied. Then, different filter examples based on $N$ cascaded singlets are designed, fabricated, and measured at 7.5 GHz, with up to $N$ transmission zeros that can be easily located below and above the passband. Moreover, the application of doublets based on a dual-mode coaxial SIW resonator with source-load coupling for achieving extremely compact dual-band filters is presented, and two examples with different bandwidth configuration for each channel are designed, demonstrating the flexibility of the proposed coaxial SIW structure. The obtained experimental results of the differently implemented filters show a good agreement with simulations, thus confirming the interesting potential application of these structures for the design of very compact devices with advanced filtering responses.

SIW‐based microfluidically tunable PD with wide‐frequency‐tuning range

A passive microfluidically tunable power divider (PD) with a wide-frequency-agile range based on substrate integrated waveguide (SIW) has been presented. The proposed structure consists of two SIW resonators loaded on the same complementary split-ring resonator and five identical filling-water tubes placed on the top plane. By injecting water into five tubes, the effective permittivity of the substrate can be controlled, and thus the operating frequency of the PD can be precisely tuned. For demonstration, the proposed PD is designed and fabricated. The measured and simulated results are given, showing good agreement.

A filter design method based on higher-order modes of fan-shaped half-mode substrate integrated waveguide resonator

A filter design method based on higher-order modes of fan-shaped half-mode substrate integrated waveguide resonator

Design of a Novel Quarter-Mode Substrate-Integrated Waveguide Filter With Multiple Transmission Zeros and Higher Mode Suppressions

This paper presents a novel quarter-mode packaged bandpass filter with four transmission zeros (TZs) in substrate-integrated waveguide (SIW) technology. The filter has an insertion loss of 2.85 dB at 30 GHz and fractional bandwidth of 20%. The design methodology of the TZs was first demonstrated to increase the attenuations of the filter stopband. The quarter-mode SIW resonators were analyzed with high-mode suppression by properly setting their feed points. The packaged filter was consistent between the simulation and measurement results and offers the advantages of compact configuration and easy integration with other devices. Mode suppressions of up to 110 GHz were also provided. The proposed concept is attractive for designing miniaturized and high-performance-packaged filters for 3-D millimeter-wave transceiver systems.

Substrate integrated waveguide resonator with harmonic suppression

A novel technique to design substrate integrated waveguide (SIW) resonator with harmonic suppression is proposed. The spurious band arising from the harmonics is designed as well as the fundamental passband. The bandwidth of the spurious band is designed to be zero to realise harmonic suppression. At the same time, the fundamental properties of the SIW are almost not affected, and no additional circuit area is required. The harmonic suppression and the fundamental passband can be designed independently of each other. An SIW resonator with harmonic suppression and an SIW filter with wide stopband are fabricated and measured to verify the proposed technique. The results agree with expectation well.