Half-mode Substrate Integrated Waveguide Research Articles

Compact Slow-Wave Half-Mode SIW Periodic Leaky-Wave Antenna With Continuous Beam Scanning and High Gain

Compact Slow-Wave Half-Mode SIW Periodic Leaky-Wave Antenna With Continuous Beam Scanning and High Gain

A compact SIW dual-functional design with integrated filter and self-diplexing antenna

ABSTRACT This paper proposes a compact dual-functional design (DFD) which integrates a bandpass filter (BPF) and self-diplexing antenna in a half-mode substrate-integrated waveguide (HMSIW) cavity. The design consists of four eighth-mode SIW (EMSIW) sub-cavities that are formed by etching three slots on an HMSIW cavity. Two of the sub-cavities are coupled to form a BPF with low insertion loss with a controllable transmission zero and a wide out-of-band rejection > 33 dB. In contrast, the other two sub-cavities are used to create a self-diplexing antenna with wide frequency tunability (2.8–5.0 GHz) with two additional narrow slots and high isolation (>22 dB). Detailed parametric studies confirmed that tuning of self-diplexing antenna has no significant impact on the performance of integrated BPF. An equivalent circuit model of the design is developed and validated with simulation and measurement results. The proposed design has a simple and compact structure, good isolation, and controllability, making it suitable for modern handheld wireless systems.

A novel modified complementary metamaterial resonator based dual-band bandpass quasi-elliptic filter using half-mode SIW cavity with wide stopband rejection for wireless communication applications

This article presents a novel dual-band metamaterial bandpass quasi-elliptic filter (DBBPF) for wireless communication applications, addressing the critical need for compact, high-performance multi-band filters in modern systems. The proposed filter leverages substrate-integrated waveguide cavity (SIWC) technology combined with innovative complementary metamaterial resonators to achieve significant miniaturization while maintaining excellent electrical performance. The filter’s design incorporates four complementary resonators of modified rectangular shape (CMSRR) on the metalized top face, generating targeted operating bands below the SIW cutoff frequency. To control their resonances, the size of each CMSRR is optimized for electrical dimensions of just 0.154 λ0× 0.115 λ0× 0.028 λ0. We present a comprehensive analysis of both full mode (FMSIWC) and half mode (HMSIWC) configurations, demonstrating dual-bandpass behavior with central frequencies at 5.79 and 9.82 GHz for FMSIWC, and 5.72 and 9.74 GHz for HMSIWC. The electromagnetic behavior of the basic cell of the filter is analyzed based on the frequency characteristics of its permittivity and permeability. A parametric study according to the location of the metamaterial resonators in the filter is conducted to have the optimized dimensions. Additionally, the confinement of the electric field in the two filter configurations is discussed to better understand their behavior. The fabricated HMSIWC filter, implemented on an FR4-Epoxy substrate measuring only 54.60 × 25.75 × 1.5875 mm3, achieves remarkable miniaturization while maintaining desired performance characteristics. Experimental results validate the simulated performance, demonstrating excellent agreement for both configurations. Key performance metrics include fractional bandwidths of 3.77 and 6.98 %, and insertion losses of 1.33 dB and 2.14 dB for the two passbands in the HMSIWC design. This work advances the state-of-the-art SIW filter design by combining half-mode techniques with optimized CMSRR structures, resulting in a compact, high-performance dual-band filter. The proposed DBBPF’s simple design and small form factor make it an ideal candidate for integration into various wireless communication systems, particularly where space constraints are critical.

A Multi-Aperture Technique for Longitudinal Miniaturization of UWB 3 dB Dual-Layer SIW Coupler.

Microwave couplers are used in large numbers in beamforming networks, and their miniaturization can lead to a significant size reduction in the overall phased array. While the miniaturization of 3 dB couplers in the transverse direction (width) has been given considerable attention in the literature, there is minimal to no information on reducing coupler length. This is because of the trade-off between aperture length, bandwidth and coupling strength. The Bethe-Hole theory requires adding multiple apertures in the longitudinal direction for wide bandwidth, thus increasing the device length. Another factor is the aperture size, which determines the coupling strength and puts additional strain on the compactness of a 3 dB coupler. Contrariwise, this paper proposes to merge two weak (and hence compact) coupling mechanisms to design a wideband 3 dB coupler. This is achieved by using a longitudinal rectangular slot and three cross-slots in the transverse direction. Because of weak coupling, the slot sizes are smaller than a conventional 3 dB coupler, hence yielding a device whose length is less than one guided wavelength (λg) without compromising the bandwidth. The presented coupler is 0.63 λg in length, which is smaller than the state-of-the-art while maintaining a fractional bandwidth of 37% that is comparable to half-mode substrate integrated waveguide (HMSIW) couplers.

Design of Cross-Coupled Bandpass Filters with Flexible Coupling via Half-Mode Substrate-Integrated Waveguide

In this article, a simple approach for achievement of flexible coupling is presented based on the half-mode substrate-integrated waveguide (HMSIW). Since both electric and magnetic fields vary along the magnetic wall of the HMSIW, there exists mixed coupling between two adjacent HMSIWs. In this context, only by adjusting the width of the coupling slot at specific regions, both coupling property and strength can be conveniently controlled. Besides, as the coupling slot possesses the merits of simple structure and high flexibility, it is also expected to achieve desired couplings between multimode resonators. For demonstration, three cross-coupled bandpass filters (BPFs) with different kinds of frequency responses are constructed based on the typical cascaded trisection coupling topology by mixing one SIW and two HMSIWs, including two single-band and one dual-band designs. All measured results are highly consistent with the simulated ones, validating that the HMSIW not only has the inherent advantage of smaller size than the conventional SIW counterparts but also possesses unique feature in providing flexible coupling without extra circuit.

Broadband Balanced-to-Balanced Filtering Power Divider Using HMSIW-SSPP Transmission Line.

In this paper, a novel broadband balanced-to-balanced (BTB) filtering power divider (FPD) utilizing the half-mode substrate-integrated waveguide and spoof surface plasmon polariton (HMSIW-SSPP) hybrid transmission line is introduced. Initially, a new HMSIW-SSPP unit cell is proposed, demonstrating a lower upper cut-off frequency compared to the classical HMSIW-SSPP unit cell. Building upon this unit cell, a bandpass BTB FPD is devised employing dual-layer stacked substrates, enabling independent control over the passband's lower and upper cut-off frequencies through specific physical dimensions. Additionally, the incorporation of isolation resistors and defected ground structures in the BTB FPD enhances differential-mode isolation and common-mode (CM) suppression between output ports. A manufactured and tested BTB FPD prototype validates this design method, showcasing a broad fractional bandwidth of 52.31% (6.72-11.48 GHz), output port isolation surpassing 14.25 dB, and transmitted CM suppression exceeding 34.05 dB.

A Compact Bandpass Filter with Active Switchable Passband Status

In order to meet the increasing demand for adjustable devices in the modern wireless communication system, a compact bandpass filter with active switchable passband is proposed. The filter is based on the half mode substrate integrated waveguide (HMSIW), and uses its cut-off characteristics to form the lower stopband. The resonant characteristics of a quarter-wavelength shorted stub generates a transmission zero (TZ) at higher frequency, which forms the upper stopband. The active control of DC power supply determines the biased states of PIN diodes to change the electrical size of the filtering parts. When the diodes are reverse biased, the filter works in C band with the passband of 3.9-5.2 GHz; when the diodes are forward biased, the passband shifts to S band of 2.7-3.6 GHz. The 28.6% relative bandwidth in both frequency bands remains constant. The simple design realizes the active switching between bands, providing a promising idea for active adjustable devices.

Hybrid self-oscillating mixer loading dielectric resonator antenna fed by half-mode substrate integrated waveguide for K-band radar

In this paper, a new self-oscillating mixer (SOM) including a dielectric resonator (DR) antenna fed by a half-mode substrate integrated waveguide (HMSIW) has been proposed using hybrid integrated circuit technique on an FR4 epoxy substrate. The HMSIW resonator with high quality factor and the DR radiator with higher order HEM13δ mode excitation are responsible for the excellent phase noise performance of the oscillator and the high directivity of the antenna, respectively. The phase noise, estimated LO power, and conversion gain were obtained as −102.5 dBc/Hz at 1 MHz offset, 8.74 dBm at an oscillation frequency of 24.15 GHz, and 8.5 dB, respectively. The figure-of-merit for the oscillator was obtained −172.8 dBc/Hz.

Design of Nonreciprocal Filtering Antenna Using Spatio-Temporal Modulated SIW Resonators

This article reports on, for the first time, the design of nonreciprocal filtering antennas using spatio-temporal modulated substrate integrated waveguide (SIW) resonators. It consists of two SIW cavities and a half-mode SIW (HMSIW) cavity, which is designed as the last-stage resonator and the radiator. By integrating time-modulated capacitors on the surface gaps of the three cavities, the nonreciprocal radiation patterns in transmission and reception modes are achieved at the same operating frequency. Three radiation nulls are generated due to the cross-coupling in the time-modulated network and source-load coupling. The theoretical analysis of the co-designed nonreciprocal SIW filtering antenna is detailed, along with methods for its co-simulations and measurements. For the proof-of-concept demonstration, a nonreciprocal SIW filtering antenna operating at 2.4 GHz is designed and fabricated. The measured 10-dB bandwidth and peak gain are 1.7% and 2.6 dBi, respectively. The measured realized gains at transmission and reception show that the reverse isolation is greater than 11 dB within a bandwidth of 30 MHz. The frequency selectivity values are 756 and 368 dB/GHz at the left and right sides of the passband, respectively.

Half-mode substrate integrated waveguide based filtering leaky-wave antenna

In this communication, a filtering leaky wave antenna based on half-mode substrate integrated waveguide (HMSIW) is proposed. The band-pass filtering response is achieved using periodic radiating slots element on high- low impedance substrate integrated waveguide. Apart from flexible filtering, the proposed antenna also shows wide range beam scanning from backward to forward quadrant of 68° in the operating frequency range of 7.7 GHz to 10.9 GHz with low dielectric material with a size of 6.73 λo. The proposed antenna is having a maximum gain of 14 dBi with gain variation of 2 dB in the operating range. To achieve continuous forward and backward beam scanning, open-stopband mitigation is necessary which is also discussed along with flexible frequency filtering.

A dual-band dual-polarized frequency beam-scanning antenna based on HMSIW and PC

A dual-band dual-polarized frequency beam-scanning (FBS) antenna based on half-mode substrate integrated waveguide (HMSIW) and photonic crystal (PC) is proposed. HMSIW can decrease the width of the substrate, and each eigenmode of PC has own unique electric-field distribution, which can be good for generating different polarization types. Therefore, the proposed antenna not only has a narrow substrate, but also has the characteristic of circularly polarized (CP) and linearly polarized (LP) radiation, which can be used for overcoming effectively the multipath fading and enhancing the channel capacity. For increasing the bandwidth of 3 dB axial ratio (AR), the slots on top surface are not perfectly symmetrical in the improved unit cell. The asymmetrical antenna based on the improved unit is manufactured and measured. The antenna can accomplish 33° scanning angle with the realized gains of 7.9–10.6 dBi in the CP working band (7.2 to 8.2 GHz), and can also achieve 24° beam-scanning for the LP radiation (8.8 to 9.6 GHz), whose realized gains are from 9.5 to 11.5 dBi. In addition, the experimental results are highly consistent with the simulated results, verifying that the design is feasible.

Super-compact equal/unequal half-mode substrate integrated waveguide filtering power dividers using complementary G-shaped resonator

ABSTRACT In this paper, three super-compact equal/unequal filtering power dividers (FPDs) by combining the half-mode substrate integrated waveguide (HMSIW) platform and the metamaterial unit cell are proposed. To miniaturized the total dimension of the proposed equal/unequal FPDs, the evanescent mode technique, the half-mode technique, and the stepped-impedance resonator (SIR) technique have been utilized, simultaneously. In the modified metamaterial unit cell, which is called the complementary G-shaped resonator (CGR) unit cell, the quasi stepped-impedance slot line is replaced instead of the conventional slot line in the circular complementary split-ring resonator (CSRR) unit cell. Accordingly, the electrical size of the modified CGR unit cell is smaller than the conventional circular CSRR unit cell with the same physical sizes. Employing the introduced CGR unit cell and HMSIW structure, three equal/unequal FPDs with arbitrary power-dividing ratios have been designed and simulated. To illustration the performance of the proposed components, three HMSIW FPDs with different power division ratios of 1:1, 1:4, and 1:8 have been fabricated and measured. A reasonable agreement between simulated and measured results has been achieved. The results demonstrate that a miniaturization factor of about 0.64 is achieved.

Substrate Integrated Waveguide-Based Dual-Polarized Self-Diplexing Antenna Array

Substrate Integrated Waveguide (SIW) cavity backed self-diplexing slot antenna array is proposed with dual-polarized capability. The antenna array is composed of four linearly placed full-duplex elements operating at 3.5 and 4 GHz independently. The antennas are designed inside a Half Mode SIW (HMSIW) cavity, and two capacitive slots adjust the resonant frequencies. Furthermore, two 1 by 4 power dividers all including 50-ohm transmission lines are designed to feed the radiators, thus resulting in a single layer antenna array integrated with feeding networks. Upon evaluating the simulated and measured results, the minimum reflection coefficients of -25 dB were observed at both operating frequencies. In addition, the data showed that the suggested structure brings about a high isolation level of more than 23 dB between two bands. It is also worth expressing that maximum gains of 10 and 11.5 dBi are obtained at 3.5 and 4 GHz, respectively. And, the radiation efficiencies are 0.78 and 0.9 for the low and high frequency bands.

Self-triplexing HMSIW antenna with enhanced isolation and extremely low frequency ratio

A self-triplexing antenna based on half-mode substrate integrated waveguide (HMSIW) cavity is proposed in this paper. The HMSIW cavity is designed as a combination of two eighth-mode substrate integrated waveguide (EMSIW) cavities and a single quarter-mode substrate integrated waveguide (QMSIW) cavity. The self-triplexing property is achieved by placing a narrow longitudinal slot on one of the EMSIW cavities and an annular cut on the QMSIW cavity. The proposed triplexer antenna operates at three distinct yet closely spaced frequencies 3.85 GHz, 4.12 GHz and 4.54 GHz with an extremely low frequency ratio (FR) of 1.18. The three operating bands are 3.82 - 3.88 GHz, 4.08 – 4.14 GHz and 4.51 – 4.57 GHz. The operating frequencies can be tuned independently by varying the dimensions of the slots. A minimum port isolation of 29 dB is achieved between the three cavities that contributes for self-triplexing property. The measured gain at three resonant frequencies is 6.02, 5.74 and 6.35 dBi, respectively. The proposed HMSIW self-triplexing antenna occupies a very small area of 0.14 λ02 (λ0 is the free space wavelength at the lowest operating frequency) and it is extremely useful for fixed wireless access and point-to-point commercial microwave applications.

Half mode rectangular SIW slotted antenna for multiband operations using ANN optimization

AbstractA multiband half‐mode substrate integrated waveguide (HMSIW) slotted antenna is developed for ISM/WiMAX/WLAN applications. HMSIW technique has been utilized to acquire antenna compactness. Two inverted L‐shaped slots of half wavelength are embedded onto a HMSIW rectangular cavity for attaining a hybrid mode (i.e., Half‐mode of Half‐mode of ), which induces a lower resonance at 2.4 GHz. An inverted L‐shaped slot is influenced to radiate hybrid mode at 2.4 GHz, while the innermost inverted L‐shaped slot radiates modified mode at 3.30 GHz. A multiband is obtained by amalgamation of hybrid mode (at 2.4 GHz), modified mode (at 3.30 GHz) and modified mode (at 5.38 GHz). The radiating modes are elucidated by using mode theory methodology for ascertaining the resonance characteristics of the prototype antenna. The antenna parameters have been optimized by artificial neural network technique using MATLAB. The antenna geometry possesses a shrinkage size of 30 × 16 × 1.6 mm3, which has been designed on FR‐4 substrate. To vindicate the simulated consequence, the fabricated prototype has been tested. It contributes the fractional bandwidth of 6.4% (2.09−2.23 GHz) in the hybrid mode at 2.18 GHz, 9.03% (2.89−3.17 GHz) in the half cavity mode at 3.10 GHz and 9.96% (5.11−5.65 GHz) in the half cavity mode at 5.42 GHz, respectively, which is beneficial for ISM, WiMAX and WLAN band wireless applications.

Wideband Low-Loss Filter With Compact Size and Wide Stopband Based on Folded Planar Waveguide

In this letter, a hybrid, compact doubly slot-loaded folded ridged half-mode substrate-integrated waveguide (FRHMSIW) filter with wide bandwidth and high selectivity is presented and investigated. The low-pass and high-pass cutoff frequencies of the wideband filter can be independently controlled by adjusting the dimensions of the quasi-periodic slots and FRHMSIW sections, respectively. The dispersion curves, surface current distribution, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$</tex-math> </inline-formula> -field vector diagram of the proposed hybrid FRHMSIW bandpass unit are illustrated. Parametric study and loss analysis are also conducted. The footprint of the proposed filter is miniaturized due to the upper-side-slot-loaded FRHSIW transmission structure and meandered middle-layer slots. The stopband is further extended by etching I-shaped patterns on the ground layer. Finally, the filter is designed, simulated, and measured, with a wide passband between 3.86 and 8.3 GHz, a minimum insertion loss of 0.56 dB, a rejection level better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 20 dB from 8.6 to 20.8 GHz, and an electrical size of only 0.21 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{g}^{2}$</tex-math> </inline-formula> at the center frequency.

A Compact Aperture-Sharing Sub-6 GHz/Millimeter-Wave Dual-Band Antenna.

In this article, a microwave (MW)/millimeter wave (MMW) aperture-sharing antenna is proposed. The antenna is constructed using two orthogonal columns of grounded vias from a 3.5 GHz slot-loaded half-mode substrate-integrated waveguide (HMSIW) antenna. These vias are reused to create two sets of 1 × 4 MMW substrate-integrated dielectric resonator antenna (SIDRA) arrays. With this proposed partial structure reuse strategy, the MW antenna and MMW arrays can be integrated in a shared-aperture manner, improving space utilization and enabling dual-polarized beam steering capability in the MMW band, which is highly desirable for multiple-input multipleoutput (MIMO) applications. The integrated antenna prototype was manufactured and measured for verification. The 3.5 GHz antenna has a relative bandwidth of 3.4% (3.44-3.56 GHz) with a peak antenna gain of 5.34 dBi, and the 28 GHz antenna arrays cover the frequency range of 26.5-29.8 GHz (11.8%) and attain a measured peak antenna gain of 11.0 dBi. Specifically, the 28 GHz antenna arrays can realize dual-polarization and ±45° beam steering capability. The dual-band antenna has a very compact structure, and it is applicable for 5G mobile communication terminals.

Miniaturized Compact Reconfigurable Half-Mode SIW Phase Shifter with PIN Diodes

In this work, a novel electrically reconfigurable phase shifter based on a half-mode substrate integrated waveguide (HM-SIW) is proposed. SIW is a guided transmission line topology, and by using half-mode excitation, a smaller size can be achieved. Phase shifters are electronic devices that change the phase of transmission for a wide range of applications, including inverse scattering and sensing. The tunability of PIN diodes is applied here to achieve a reconfigurable design. The proposed single-layer structure does not require extra wiring layers for the bias circuit on the suggested printed circuit board. Its principle consists in the integration, in the HM-SIW, of three parallel lines, each connecting the edge of the HM-SIW and linked to a PIN diode and a radial stub. Here we present the results of measurements for a frequency band from 4.5 to 7 GHz that demonstrate how the experiment agrees with simulations. Insertion loss was less than −10 dB, and port coupling was less than −2 dB for both simulation and measurement solutions. The proposed half-mode structure is around half the size of a typical SIW line. With the proposed design, the seven states of the PIN diodes can be validated (ON and OFF), with a wide band adaptation and a relatively constant phase difference across a broad frequency range (44%). A key benefit of the proposed design for a microwave component is the reduction of extra biasing layers for the PIN diodes. This is in addition to the reduced size of the transmission line compared to a commercial SIW. In the annexed section, simulation software is used for a more comprehensive analysis involving more phase shift values and parametric studies.

Metamaterial and SIW inspired isolating fences for lateral de-coupling in MIMO antenna

This paper proposes seven isolating fences (IF) for MIMO using novel rotated complementary split ring resonators (RCSRR) and half-mode substrate integrated waveguides (HMSIW) for decoupling. The removing mutual coupling, especially in the lateral direction that is mainly due to surface and space waves is challenging in MIMO. The proposed method involves the RCSRR, HMSIW, and defected ground structure (DGS) to reduce the lateral mutual coupling. In terms of S parameters, radiation pattern, envelope correlation coefficient (ECC), diversity gain (DG), channel capacity, mean effective gain (MEG), and efficiency the performance of the MIMO antenna is examined. The proposed MIMO has the size of 35 × 48 × 1.6 mm3 is made of FR4 substrate material with a centre frequency of 10 GHz, a bandwidth (BW) of 12 GHz, and a gain in the range of 3.7–4.3 dBi.

Filtering SIW phase shifter based on through quartz vias technology

A filtering SIW phase shifter based on through quartz vias (TQVs) technology is demonstrated in this paper. The passband filter operates in the quasi-TEM mode of the half-mode substrate integrated waveguide (HMSIW) resonator. The slot and complementary split-ring resonators (CSRRs) are etched on the top metal of the filter to adjust the performance of the passband and achieve phase shift. The filtering phase shifter is centered at 17.37 GHz with 10° and 30° phase shift and the fractional bandwidth of the filter is 10.6%.