Half-mode Substrate Integrated Waveguide Research Articles

Four-Way Chained Quasi-Planar Slotted-HMSIW Power Divider

A four-way chained quasi-planar slotted power divider, using half-mode substrate-integrated waveguide technology, is presented in this letter. Based on the equivalent-circuit model, slotted capacitive coupling model has been achieved. In order to verify the validity of the design method, a four-way power divider operating at X-band is designed, fabricated and measured. The simulation and measured results with good agreement are presented. The measured insertion loss (in the frequency range of 9.05–9.55 GHz) is less than 1.4 dB, and the return loss is better than 17.5 dB. The measured isolations between the output ports are greater than 12 dB at the entire design band.

Miniaturised ISM band HMSIW band‐pass filter loaded with wide U slot

In this study, two half-mode substrate integrated waveguide (HMSIW) filters are proposed by introducing wide U slot in the conventional SIW (substrate integrated waveguide) structure. In the first case, lower ISM (industrial, scientific and medical radio) band HMSIW filter is designed by extending the centre stub, thereby controlling the resonant frequency and bandwidth. In the second case, higher ISM band HMSIW filter is designed by shorting the extended stub using via. These filters are having a compact core size of 26 mm × 11 mm and work at 2.4 and, 5.8 GHz with a fractional bandwidth of 4.0 and 2.6%, respectively. The filter is fabricated with a single layer standard printed circuit board process. The measured results are good and in agreement with simulated results. The band-pass filter structure has the advantage of low insertion loss, good return loss, sharp side band rejection and compact size.

A dual-band half-mode substrate integrated waveguide-based antenna for WLAN/WBAN applications

A dual-band half-mode substrate integrated waveguide (HMSIW) based cavity-backed antenna is proposed for WLAN/WBAN applications at 5/5.8 GHz, respectively. A semi-hexagonal slot is introduced on the top plane of the cavity primarily for radiation. This slot offers miniaturization for both the TM210 and TM020 modes. Later on, two rectangular slits are loaded on the open edge of the patch, to provide miniaturization and tuning mainly for the higher frequency band. The performance of the proposed antenna is investigated in free space and in proximity of the pork tissues. In free space conditions, the measured −10 dB fractional bandwidths are 3% and 3.1% along with peak gains of 6.25 and 6 dBi for the frequency bands at 5 and 5.8 GHz, respectively. In proximity of the pork tissues, the measured fractional bandwidth is 3.2% along with the efficiency of 81.5% at 5.8 GHz. The specific absorption rate (SAR) is 0.48 mW/g averaged over 1 g of tissues with 100 mW input power.

Development of Compact HMSIW Gysel Power Dividers With Microstrip Isolation Networks

Based on the concept of conventional Gysel power divider, a novel concept of half-mode substrate integrated waveguide (HMSIW) Gysel power divider was reviewed and developed, by simply combining a traditional HMSIW power divider and a microstrip isolation network. The proposed concept was reviewed, investigated, and analyzed thoroughly, after that, $Y$ -type, $T$ -type, and Parallel-type HMSIW Gysel power divider were designed and analyzed, respectively. Furthermore, based on Parallel-type design, a developed version using two isolation networks was proposed for frequency bandwidth enhancement. All the four prototypes were fabricated and measured for verification and comparison. The good electrical performances and compact configuration indicate the advantages of the proposed concept and an excellent candidate for high power-handling HMSIW/SIW circuits or systems.

Wideband Half-Mode SIW Power Divider With Improved Output Isolation Using Slotline Isolation Technology

A wideband half-mode substrate integrated waveguide (HMSIW) power divider with bandpass-filtering response using the slotline isolation technology is presented in this paper. Resistive slot on the bottom layer is employed to improve the output isolation. To obtain filtering response, L-type slot line and two multimode SIR resonators loaded symmetrically at two sides of the input transmission line are employed to generate transmission zeros at upper stop band. In addition, filtering response is achieved by combining the inherent high-pass characteristic of the HMSIW and the TZs. The equivalent circuits are presented and analyzed by using even- and odd-mode method, and the relative design equations are derived. The measured return loss of the HMSIW power divider is about 10 dB and its isolation is greater than 15 dB from 3.8 to 5.8 GHz. All measured results show reasonable agreement with the simulated ones.

Dual-Mode Characteristics of Half-Mode SIW Rectangular Cavity and Applications to Dual-Band Filters With Widely Separated Passbands

The dual-mode characteristics of the half-mode substrate-integrated rectangular cavity (HMSIRC) are systematically analyzed for the first time and experimentally demonstrated by two planar substrate-integrated waveguide (SIW) dual-band bandpass filters (DBBPFs) with widely separated passbands. The mode spectrums in an HMSIRC and their constraint relationships are comprehensively investigated first to explore the realizable frequency ratio of the second mode (TE301 or TE102) to the first one (TE101). The maximum frequency ratio of 1.63 for TE301/TE101 and 1.72 for TE102/TE101 can be achieved considering the spacing between the second and third resonances. Subsequently, the formulas of determining the physical dimensions of the dual-mode HMSIRC are derived and validated. The factors impacting the unloaded quality factor Q u of the HMSIRC are also discussed and the square single-mode quarter-mode substrate-integrated rectangular cavity has been investigated. Two compact planar SIW DBBPFs, including a third-order direct-coupled one with frequency ratio of 1.5 based on TE101 and TE301 dual-mode HMSIRC, and a fourth-order cross-coupled one with frequency ratio of 1.7 based on TE101 and TE102 dual-mode HMSIRC, are synthesized and designed for verification.

Reconfigurable Coplanar Waveguide (CPW) and Half-Mode Substrate Integrated Waveguide (HMSIW) Band-Stop Filters Using a Varactor-Loaded Metamaterial-Inspired Open Resonator.

An open ring resonator (ORR) loaded with a varactor diode is designed and implemented in order to achieve high-performance tunable band-stop filters in planar technology with a compact size. This varactor-loaded ORR (VLORR) is versatile. It allows a shunt connection with different planar waveguide sections. In this paper, it has been connected to a coplanar waveguide (CPW) and a half-mode substrate integrated waveguide (HMSIW). As a reverse bias voltage is applied to the VLORR, a continuous tuning over the resulting stop-band can be achieved. To illustrate the possibilities of the VLORR, three prototypes have been designed, fabricated, and characterized. The three prototypes show an outstanding performance, with a rejection level at the resonant frequency and a tuning range greater than 12 dB and 85%, respectively. This VLORR has high potential value in microwave communication systems to eliminate unwanted signals.

A Leaky Wave Antenna Design Based on Half-mode Substrate Integrated Waveguide Technology for X Band Applications

A new type of leaky-wave antenna (LWA) using half-mode substrate integrated waveguide (HMSIW) as the base structure is proposed in this paper. The structure consists of an array of slot, antenna designed to operate in X band applications from 8 to 12 GHz. HMSIW preserves nearly all the advantages of SIW whereas its size is nearly reduced by half. The antenna radiates one main beam that can be steered from the backward to the forward direction by changing frequency.

A Novel 60 GHz Wideband Coupled Half-Mode/Quarter-Mode Substrate Integrated Waveguide Antenna

A novel wideband substrate integrated waveguide (SIW) antenna topology, consisting of coupled half-mode and quarter-mode SIW resonant cavities, is proposed for operation in the 60 GHz band. This innovative topology combines a considerable bandwidth enhancement and a low form factor with compatibility with low-cost printed circuit board manufacturing processes, making it excellently suited for the next generation, high data rate wireless applications. Moreover, exploiting SIW technology, a high antenna-platform isolation is obtained, enabling dense integration with active electronics without harmful coupling. The computer-aided design process yields an antenna that covers the entire 57–64 GHz IEEE 802.11ad band with a measured fractional impedance bandwidth of 11.7% (7 GHz). The measured maximum gain and radiation efficiency of the prototype are larger than 5.1 dBi and 65%, respectively, within the entire impedance bandwidth.

A miniaturized evanescent mode HMSIW humidity sensor

A passive evanescent mode half-mode substrate integrated waveguide (HMSIW) resonator loaded with a complementary split ring resonator (CSRR) is designed and fabricated for humidity sensing applications. The use of the CSRR which is etched on the top plane of the HMSIW can significantly reduce the size of the device. Without any sensing material, the sensor which has a compact size of 0.17λg × 0.17λg can provide high humidity sensitivity up to 5.82 MHz/%relative humidity (RH) at high RH region (>84.3%). The results indicate that the proposed structure is a promising candidate for radio and microwave humidity sensing applications.

Continuously tunable crossover based on HMSIW

A frequency-tuning crossover based on half-mode substrate-integrated waveguide (HMSIW) is presented for the first time. Two HMSIW transmission lines are parallelly arranged to form the four-port crossover. Three tunable capacitors placed between the HMSIW transmission lines are used to obtain the tunable passband. For verification, both simulated and measured results are given and good agreement between the simulation and measurement is observed. The measured passband can be tuned in a frequency range from 2.2 to 5.0 GHz (tuning range of 78%) with better than 19 dB return loss and 15 dB isolation, while the insertion loss varies from 0.93 to 1.97 dB.

Fabrication of miniaturized CSRR-loaded HMSIW humidity sensors with high sensitivity and ultra-low humidity hysteresis

In this work, half-mode substrate integrated waveguide (HMSIW) resonators loaded with a complementary split ring resonator (CSRR) are designed and fabricated for humidity detection application. Introduction of the CSRR can significantly reduce the dimensions of the HMSIW devices in order to meet the demand for device miniaturization. Graphene oxide (GO) is used as the humidity sensing material and is deposited on the different regions of the surface of the CSRR. A series of experimental results indicate that high humidity sensitivity and ultra-low humidity hysteresis can be achieved when GO films are deposited on the central conducting patch of the CSRR. The sensor shows a high sensitivity of up to 772kHz/%RH in the humidity range of 11.3% to 84.3% and 3.415MHz/%RH in the high humidity range (>84.3% RH), and an ultra-low humidity hysteresis (0.07% RH) in the range of 11.3% to 97.3% RH. This work provides a promising approach for the realization of miniaturized microwave humidity sensors with high sensitivity and ultra-low humidity hysteresis.

Substrate Integrated Waveguide Filters Based on a Dielectric Layer With Periodic Perforations

This paper presents a novel class of substrate integrated waveguide (SIW) filters, based on periodic perforations of the dielectric layer. The perforations allow to reduce the local effective dielectric permittivity, thus creating waveguide sections below cutoff. This effect is exploited to implement immittance inverters through analytical formulas, providing simple design rules for the direct synthesis of the filters. The proposed solution is demonstrated through the design and testing of several filters with different topologies (including half-mode SIW and folded structures). The comparison with classical iris-type SIW filters demonstrates that the proposed filters exhibit better performance in terms of sensitivity to fabrication inaccuracies and rejection bandwidth, at the cost of a slightly larger size.

Portable Six-Port Reflectometer for Determining Moisture Content of Biomass Material

A portable six-port reflectometer for determining moisture content of biomass material is proposed for the first time in this paper. The proposed system consists of a 5.13-GHz reflectometer used with an open-ended half-mode substrate-integrated waveguide sensor. The complex permittivity of biomass (sawdust) was measured, and a dielectric-properties-based algorithm for moisture determination was developed. The reflectometer performance was verified by comparing the measured complex permittivity to results obtained with a commercial automatic network analyzer. Finally, the predicted moisture content was compared with the standard oven drying method.

Design of a Compact UWB Filter With High Selectivity and Superwide Stopband

This letter presents a design of compact ultra-wideband bandpass filter (BPF) with high selectivity and superwide stopband. Three resonant modes from the multiple-mode resonator (MMR) based on half-mode substrate integrated waveguide (HMSIW) structure and four resonant modes from a pair of electromagnetic bandgap loaded parallel-coupled lines can constitute a wideband performance. Superwide stopband can be achieved and two transmission zeros are realized on both sides of the passband to improve the filter selectivity. A prototype of the BPF operating from 3.1 to 10.4 GHz with an extremely broad stopband region from 10.7 to 24 GHz and a rejection level of 15 dB is demonstrated in the measured results.

Energy Leakage and Characteristic Analysis of HMSIW and Implement in Multi-layered Structure Equalizer Design

The phase constant and attenuation constant of half mode substrate integrated waveguide (HMSIW) are calculated using an improved quicker multi-line method in this paper. A mathematical method is proposed to analyze the energy leakage of HMSIW theoretically. The radiation and leakage character of electromagnetic field at open face of HMSIW is different with different relative permittivity. An equalizer loaded multi-layered HMSIW resonant cavities is proposed based on the energy leakage excitation without external coupling structure. Compared with the other planar circuits, these structures have superiorities of small size, simple structure, low loss and high Q, suitable for the miniaturization development, and are easily integrated with other circuits. Furthermore, this proposed equalizer has a simpler design procedure than other HMSIW equalizers without resonant frequency deviation.

A broadband half mode substrate integrated waveguide balun using composite right/left‐handed transmission line

AbstractA broadband half mode substrate integrated waveguide (HMSIW) balun using composite right/left‐handed transmission line is proposed. The proposed structure is consisted of a broadband microstrip Wilkinson power divider and two phase adjusted‐HMSIWs, new CRLH‐HMSIW and HMSIW thru. The broadband microstrip Wilkinson power divider is bridged with the HMSIW in/outputs. The new CRLH‐HMSIW is designed with surface mounted capacitors and printed circuit board (PCB) embedded inductors on the open edge of the HMSIW. The measured prototype shows a 1 dB amplitude imbalance and 180° ± 5° phase difference in a frequency band of 8–13.3 GHz, which has 50% fractional bandwidth. The simulation shows a good agreement with the measurement.

Size‐reduced dual‐band HMSIW cavity filters loaded with double‐sided SICSRRs

Two size-reduced dual-band half-mode substrate integrated waveguide (HMSIW) cavity filters double-side-loaded with the conventional and stepped-impedance complementary split-ring resonators (SICSRRs) are presented. The SICSRR can exhibit larger equivalent electrical length than the conventional CSRR and thus provides a method to implement size-miniaturisation. By loading both CSRR and SICSRR into the two sides of the HMSIW cavity, a dual-band resonator is formed. Since sizes of the CSRR and SICSRR on the two sides are controlled independently, the two passbands of the proposed resonator can be tuned flexibly. With the proposed HMSIW-DS-SICSRR cavity resonators, two dual-band filters are realised. Compared to other dual-band SIW filters, the two proposed dual-band filters can achieve sized-reduction about 48.5 and 50%, with the measured results in good agreement with the simulated ones.

Edge‐radiating slot antenna based on half‐mode substrate integrated waveguide

Lots of substrate integrated waveguide (SIW) slot antennas appear to satisfy the extensive and intensive growth of wireless communication systems. However, there were few reports about edge-radiating slot antenna based on SIW technology. In this study, a half-mode SIW (HMSIW) edge-radiating slot antenna is proposed for the first time by etching transversal slots both on the upper and lower surfaces of HMSIW. The radiation field of this antenna has been deduced from the field distribution of HMSIW. A 6-slot-pair antenna worked at 3.0 GHz with gain of 5.8 dBi is obtained by regulating the size and the number of slots. Through setting matching posts and a terminal load, the bandwidth can be expanded from 2 to 9.7%. The measured results show that the matching-type antenna has radiation efficiency about 0.59, beam directions ranging from 0° to 53° and gains within 5.0–7.5 dBi in 3.05–3.35 GHz. This antenna has advantages of low profile, easy fabrication, wide bandwidth and frequency-scanning property, which are great for microwave radar applications.

Density-independent algorithm for sensing moisture content of sawdust based on reflection measurements

A density-independent algorithm for moisture content determination in sawdust, based on a one-port reflection measurement technique is proposed for the first time. Performance of this algorithm is demonstrated through measurement of the dielectric properties of sawdust with an open-ended half-mode substrate integrated waveguide (HMSIW) sensor. For accurate measurement of the dielectric properties of sawdust, the HMSIW sensor was calibrated by using a three-material calibration technique, with air, water and 25% ethanol aqueous solution. For moisture determination, a density-independent calibration function expressed in terms of the dielectric properties was used. Both moist and dry bulk densities were considered for the complex-plane representation of the dielectric properties. Results of moisture prediction, relative to each complex-plane representation were found to be similar at 5 GHz and 23 °C with the standard errors of performance of 0.955% and 0.957%, respectively.