Substrate Integrated Waveguide Resonator Research Articles

Compact Dual-Band Balanced SIW Bandpass Filter With Improved Common-Mode Suppression

The contribution of this letter is to propose a novel substrate integrated waveguide (SIW) dual-band balanced bandpass filter (BPF), which exhibits characteristics of compact size and improved common-mode (CM) suppression. Two diagonal resonant modes TE102 and TE302 in a square SIW resonator with symmetric field distributions provide the possibility to realize balanced inputs/outputs, dual-passband responses and the vertically stacked structure for compact size. Without affecting the differential-mode (DM) responses, a novel method of using slotlines etched on one broadside of either SIW resonators to shift the resonant frequency of CM away from the DM passband is also proposed, to realize a higher CM rejection for this BPF. Meanwhile, perturbation vias have been utilized to adjust the center frequency of the lower passband, while the higher passband can remain almost unchanged. A second-order prototype is designed for the demonstration. Good agreement between simulation and measurement has been observed in the measurement.

Pedestal substrate integrated waveguide resonators and filters

A new substrate integrated waveguide resonator in the form of a square- or cross-shaped pedestal is proposed. The structure is developed from T-shaped ridge waveguides, and utilises the mode separation characteristics of this type of guide to achieve wider spacing between the first two resonances, as well as miniaturisation of the resonator. Two fourth-order X-band filters, one with cross-coupling, are designed using, respectively, square- and cross-shaped pedestal resonators, and validated by simulation and measurement.

SIW resonator humidity sensor based on layered black phosphorus

A passive microwave substrate-integrated waveguide (SIW) resonator humidity sensor using black phosphorus (BP) as sensitive layers has been presented. The proposed structure consists of an SIW cavity resonator operating at S-band and a folded sensing slot opened on the top plane. The humidity sensing performances of the proposed sensor were tested in the relative humidity range of 11–97%. Compared with an SIW resonator without BP sensitive layers, the sensitivity of the proposed SIW sensor with BP nanosheets significantly increased about 40 times.

High-Q Substrate Integrated Waveguide Resonator Filter With Dielectric Loading

A planar cavity is proposed, designed, and implemented with a hybrid substrate integrated waveguide (SIW) and periodically drilled SIW (PDSIW) structure. Air holes are added to synthesize a lower effective permittivity. The periodicity can increase the stored energy and improve the quality factor. The optimal ratio between the two permittivities is investigated. The measured results show that the proposed resonator has an unloaded quality factor ( ${Q}_{u}$ ) of 815, which is 53% higher than its standard SIW counterpart. To demonstrate the potential of the proposed PDSIW cavity, a third-order filter is designed and implemented through the proposed cavity, and it is then compared with filters of different orders. The new filter with a cavity shows performance enhancements in terms of both loss and bandwidth. The SIW resonator can be a promising element for use in the design of high-performance microwave filters and oscillators.

Novel Dual-Mode Bandpass Filters Based on SIW Resonators under Different Boundaries

Two novel substrate integrated waveguide (SIW) resonators under different boundaries are proposed and analyzed. The closed-form solutions of the guided-mode field and the formulas for calculating the resonant frequencies of the SIW resonators under different boundaries are given. The coexistence mechanism of quasi-TEM (TE00) and TE mode was illustrated by the proposed equivalent principle. Two modes of each filter, TE100 (TEM mode) and TE102, TE001 (TEM mode) and TE201, can be tuned independently by the perturbation slotlines. Finally, two dual-mode SIW bandpass filters utilizing the two SIW resonators are fabricated to demonstrate the proposed method. The measured results are in agreement with the simulated results.

Novel Tunable Bandstop Resonators in SIW Technology and Their Application to a Dual-Bandstop Filter with One Tunable Stopband

Two novel tunable bandstop resonators in substrate integrated waveguide (SIW) technology are presented: a ridged SIW resonator and an open-ended coplanar waveguide (CPW) resonator that is etched into the SIW’s top metallization. The ridged SIW resonator shows a tuning range of 200 MHz at 5.54 GHz. The CPW resonator has a tuning range of 600 MHz at 3.8 GHz. The two bandstop resonators are combined to design a dual-band bandstop filter with one tunable stopband. Measured results confirm that the tunable bandstop circuits presented in this letter can be effectively used in reconfigurable SIW systems.

Multilayer Substrate Integrated Waveguide (SIW) Filters With Higher-Order Mode Suppression

This letter presents a multilayer approach for suppressing the higher order modes of substrate integrated waveguide (SIW) bandpass filters. Rectangular SIW resonators in multilayer substrates can be vertically coupled with magnetic and/or electric coupling by the proposed apertures etched on the middle metal layer. Harmonic passbands produced by the first higher-order mode $\text{TE}_{102}$ can be suppressed thanks to the proposed weak coupling or mixed coupling schemes in connection with the $\text{TE}_{102}$ mode. Compared with conventional horizontally coupled filter, the proposed filters also show a compact physical size. To demonstrate the proposed design method, two double-layered SIW bandpass filters Filter (I and II) are fabricated and measured. The experimental results show that the maximum rejection levels at the $\text{TE}_{102}$ mode frequencies are below −30 dB and −20 dB for Filter I and II, respectively. Furthermore, simulated and measured results also show a good agreement.

Compact SIW dual‐band bandpass filter using novel dual‐resonance quasi‐SIW‐transmission‐line‐structure resonators

A compact substrate integrated waveguide (SIW) dual-band bandpass filter (DBSF) using novel quasi-SIW-transmission-line-structure resonators is proposed in this study. This dual-resonance SIW resonator which works in TE100 mode and TE201 mode can be evolved from a conventional SIW-transmission line or a two-conductor transmission line. Multiple signals transmission paths bring extra transmission zeros (TZs) and improve the selectivity and out-band rejection of the DBSF. This filter works at 4.75 GHz/4.82 GHz, 5.38 GHz/5.51 GHz with 3 dB fractional bandwidths of 3.8 and 3.9%, respectively, and has six TZs. The measured results agree with the simulation results well.

Highly‐selective pseudoelliptic filters based on dual‐mode substrate integrated waveguide resonators

A non-degenerate dual-mode resonator derived from circular substrate integrated waveguide is proposed, and two pseudoelliptic bandpass filters with non-resonant mode based on the dual-mode resonators are presented. Two resonant modes (higher order modes) are employed to degenerate a passband, while a non-resonant mode (fundamental mode) is designed to provide a direct input-to-output coupling. Owning to an additional path provided by non-resonant mode, the filters have good selectivity and very compact size. The presented simulation and measurement results are in good agreement.

A Novel Microwave Attenuator on Multilayered Substrate Integrated Waveguide

In this paper, we propose a novel microwave attenuator based on the multilayered substrate integrated waveguide (SIW). The large loss tangent of Flame Resistant-4 (FR-4) material in the Ku band is employed to design a highly lossy SIW resonator cavity as block element for the exploration of this attenuator. The relative permittivity and loss tangent of FR-4 at high frequency are at first experimentally extracted by testing a fabricated ring resonator on FR-4 substrate. Then the characteristics of single unit of this attenuator versus a few critical geometrical dimensions are studied. Next, an equivalent circuit of this single-unit structure is developed to theoretically predict the propagation characteristics of the designed attenuator in an efficient and effective manner. Finally, an example of SIW-based attenuator is designed and measured. The measured attenuation factor agrees with the simulated and predicted ones in the stopband frequency of our concern. In addition, good impedance matching at input and output ports is satisfactorily realized.

A K‐band push–push oscillator employing differential transmission line loaded with SIW cavity operated in TM110 mode

ABSTRACTIn this letter, a novel differential transmission‐line (TL) loaded with circular substrate integrated waveguide (SIW) cavity is presented for realizing K‐band push‐push oscillator. The SIW cavity is working at TM110 mode to enforce the 180° phase difference between two sub‐oscillators, and the tuning metal vias perturbation is introduced in the SIW resonator to maximize the distance between desired odd TM110 mode and adjacent even modes to stabilize the oscillation mode. Unlike the conventional SIW resonator structure, this differential TL possesses a reflective‐type property at the resonance frequency. A 19.76 GHz push–push oscillator based on this differential TL is designed and implemented. The measured suppression of fundamental frequency component is −25.62 dBc, and the phase noise is −118.1 dBc Hz−1 at 1 MHz offset frequency, which corresponds to a figure‐of‐merit (FOM) of −191 dBc Hz−1. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1217–1221, 2016

W-Band Characterizations of Printed Circuit Board Based on Substrate Integrated Waveguide Multi-Resonator Method

This paper provides a broadband measurement method at W-band for printed circuit board (PCB) properties using multiple substrate integrated waveguide (SIW) resonators, i.e., SIW multi-resonator method. Eight SIW resonators are designed in series fed by a rectangular waveguide through coupling slots. All resonators operate at TE101 mode with different resonant frequencies. Multi-resonator Foster form is employed to obtain unloaded resonant frequency of each SIW cavity. After introducing the testing procedure, a number of samples based on different PCBs are fabricated and accurately measured to verify the feasibility of this method.

COMPACT COAXIAL PROBE-FED CP SUBSTRATE INTEGRATED WAVEGUIDE CAVITY-BACKED ANTENNA UTILIZING SLOT SPLIT RING

A circularly polarized (CP) substrate integrated waveguide (SIW) cavity-backed slot antenna is proposed. A slot split ring (SSR) etched on the top metal surface of an SIW resonator is employed to generate the right-handed circularly polarized (RHCP) wave. The proposed antenna is excited directly by a coaxial probe with a proper distance from the symmetric axis of the SSR resonator. A prototype of the proposed CP antenna at the center frequency of 10 GHz is manufactured. As a result, the proposed antenna exhibits the advantages of both conventional planar antennas and metallic cavity backed antennas, including simple structure, compact size of 15.8×15.8 mm 2 , light weight, easy fabrication, high gain and wide axial ratio bandwidth. It is proved by experiment that an impedance bandwidth of 10.2% for the reflection coefficient less than −10 dB, an axial ratio (AR) bandwidth of 1.72% for AR less than 3 dB, and a RHCP gain 5.5 dBi have been obtained.

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.

FLAT-PASSBAND SUBSTRATE INTEGRATED WAVEGUIDE FILTER WITH RESISTIVE COUPLINGS

A lossy filter with resistive coupling is proposed based on substrate integrated waveguide (SIW) resonators, where nonresonating nodes are not required to simplify the realization. The sensitivity analysis of S-parameter to the resistive coupling coefficient is carried out to determine the parameters of coupling structure and mounted resistors. When resistive couplings are added to the structure, the measured 0.2-dB passband bandwidth increases from 198 to 256 MHz, compared with the case without resistive couplings. At a sacrifice on the additional insertion loss of 1.1 dB, the passband flatness and selectivity are improved significantly. The lossy SIW filter can provide a smaller in-band insertion loss than the microstrip counterparts, because the unloaded Q-factor of SIW resonators is higher than that of microstrip resonators. Moreover, a simpler topology and a less insertion loss are obtained in the proposed resistively coupled SIW filter than those of the lossy filter synthesized with lossy coupling matrix. Excellent agreement between the simulated and measured results is achieved to demonstrate our idea.

Cross-coupled bandpass filter based on circular substrate integrated waveguide resonator

Cross-coupled bandpass filter based on circular substrate integrated waveguide resonator

Quasi Eighth-Mode Substrate Integrated Waveguide (SIW) Fractal Resonator Filter Utilizing Gap Coupling Compensation

AbstractIn this paper, a kind of quasi eighth substrate integrated waveguide resonator (QESIWR) with defected fractal structure (DFS) is proposed firstly. Compared with the eighth substrate integrated waveguide resonator (ESIWR), this kind of resonator has lower resonant frequency (

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.

Design of K-Band Substrate Integrated Waveguide Band-Pass Filter with High Rejection

This article presents the design of K-band Substrate Integrated Waveguide (SIW) Band-pass filter with high rejection, by using the topology with iris and the SIW resonators. The simulated results of this filter have shown that the passband is from 17.3 GHz to 19.3 GHz, while the insertion loss is 1.35 dB within 10.9 % bandwidth around 18.3 GHz and input return loss in the passband is better than 15 dB, with high rejection of -57.88 dB at the frequency 24.07 GH. All the structures are designed on a single substrate of Rogers R04003 permittivity 3.55. The compatibility with planar circuits is provided via a specific microstrip transition (microstrip tapered transitions).

Ultra-Miniature SIW Cavity Resonators and Filters

This paper presents ultra-miniature substrate integrated waveguide (SIW) cavity resonators, and filters by employing ramp-shaped slots as interdigital capacitors (IDCs) to force the structure to operate in the first negative-order resonance mode. Additionally, a metal patch in the middle metal layer along with disconnected vias is used to increase the equivalent series capacitance of the resonator and accordingly the miniaturization factor. By applying this method to half-mode SIW (HMSIW) and quarter-mode SIW (QMSIW) resonators, 90%, and 95% of miniaturization is achieved, respectively, compared to conventional full-mode SIW resonators. Afterwards, a two-pole bandpass filter is proposed based on the presented QMSIW resonator. Also, by using a combination of HMSIW and QMSIW ultra-miniature resonators, two trisection filters with a controllable transmission zero on either side of the passband are presented. To the best of authors' knowledge, this is the first disclosure of simultaneous use of HMSIW and QMSIW resonators to achieve asymmetric filter response with an ultra-compact size.