Quarter-mode Substrate Integrated Waveguide Research Articles

Ultracompact Quarter-Mode SIW Self-Hexaplexing Antenna for C-Band and X-Band Applications

Ultracompact Quarter-Mode SIW Self-Hexaplexing Antenna for C-Band and X-Band Applications

Highly-isolated compact self-diplexing antenna

This article introduces a novel low-profile self-duplexing antenna with high isolation for out-band operation applications. The antenna design features two patches, one rectangular and one triangular, both utilizing the quarter-mode substrate integrated waveguide (QMSIW) cavity for enhanced performance. Furthermore, miniaturization is achieved through the incorporation of capacitive slots. The resulting self-duplexing antenna is engineered for operation at both 5.8 and 9.8 GHz frequencies, with an impressive alignment between measured and simulated results. Notably, the antenna’s dimensions are remarkably compact, occupying only 0.08 λg2, while still delivering a remarkable 40 dB isolation between its two ports. Furthermore, the antenna maintains consistent radiation patterns at both frequencies. Simulated gains at 5.8 and 9.8 GHz are 4.1 and 4.6 dBi, respectively, enhancing its suitability for dual-band wireless communications. An additional advantage of this design is its independent tuning of frequency bands, facilitated by adjusting the size of the capacitive slots. The article also delves into the investigation of the tuning circuit model for the self-diplexing antenna, which is crucial in the design process. This model elaborates on how the antenna operates and how the frequency bands can be regulated, providing valuable insights into its functionality and versatility. Moreover, the proposed antenna stands out as the most compact self-duplexing antenna with the highest level of isolation when compared to existing literature, making it a valuable asset for dual-band wireless communication applications.

Wide stopband QMSIW diplexer with large frequency ratio and flexible specification

AbstractIn this letter, a wide stopband quarter‐mode substrate‐integrated waveguide (QMSIW) diplexer is proposed. By using coupling feeding lines and QMSIW cavities, the two passbands of the diplexer can be controlled independently by their respective QMSIW bandpass filters. In comparison to other counterparts, the proposed diplexer provides flexible passband specification, compact size, and high isolation. The design exhibits a wide 20‐dB stopband up to 3.2f0, a frequency ratio of 1.6, and a high isolation level larger than 42.2 dB across the passbands.

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.

A Quad-Band Shared-Aperture Antenna Based on Dual-Mode Composite Quarter-Mode SIW Cavity for 5G and 6G with MIMO Capability

This study introduces a new design for an ultra-compact shared-aperture antenna utilizing a quarter-mode substrate integrated waveguide (QMSIW) cavity. The proposed antenna operates as a 4 × 4 multi-input multi-output (MIMO) system in three 5G/6G millimeter-wave (MMw) bands, while functioning as a single element antenna for a 5.5 GHz wireless fidelity Microwave (Mw) band. The antenna comprises four QMSIW cavity resonators; each QMSIW is loaded with dual slots to produce tri-band MMw operation at 28 GHz, 38 GHz, and 0.13 THz. The four cavities are arranged to reuse the entire aperture by creating a conventional open-loop antenna that operates at a frequency of 5.5 GHz. Simulation, measurement, and co-simulation results show that the proposed antenna has a quad-band operation and exhibits favorable characteristics. The measured scattering parameters validate the simulated ones over the four bands under consideration. The lowest values of the measured total radiation efficiencies are 80%, 73%, 62%, and 72% (co-simulation) within the four covered bands, respectively. The antenna peak gains are 1.8 to 1.85 dBi, 4.0 to 4.5 dBi, 4.3 to 4.5 dBi, and 6.5 to 6.6 dBi within the covered bands. Furthermore, the design satisfies MIMO and diversity conditions (envelope correlation coefficient and branch power ratio) over frequency bands of operation. All excellent results are achieved from an ultra-compact size in terms of footprint area (0.018λ02), where λ0 represents the free space wavelength at 5.5 GHz. The antenna boasts an excellent reuse aperture utilization efficiency (RAU) of 92% and a large ratio frequency of 23, making it an ideal candidate for compact devices. With its superior performance, the proposed design is well-suited for a range ofs wireless communication systems, including mobile devices and the Internet of Things.

Compact self‐multiplexing antenna with high isolation and small‐frequency ratio

AbstractIn this paper, a miniaturized quarter‐mode substrate integrated waveguide (QMSIW)‐based self‐multiplexing antenna is designed to achieve high isolation in terms of small‐frequency ratios. First, the cross‐shaped slot is introduced to split the antenna into four parts with different dimensions, equivalent to four QMSIWs with different frequencies. By adjusting the slot position parameters, the QMSIW can be adjusted independently. Second, the antenna placement is optimized by adjusting the position of the slot and applying the frequency spacing technique. The designed antenna operates in four similar frequency bands (4.8, 5.15, 5.5, and 5.8 GHz). The isolation of adjacent units is more remarkable than 35.1 dB, while the isolation of relative units is more excellent than 22.7 dB. The structure of the proposed planar antenna is simple and suitable for handheld microwave devices.

Compact dual‐band bandpass filter with high selectivity based on spiral‐stub‐loaded dual‐mode QMSIW resonators

AbstractA novel miniaturized dual‐band quarter‐mode substrate integrated waveguide (QMSIW) bandpass filter with high selectivity is proposed in this letter. Two passbands are generated by the fundamental mode and the first higher order mode of the spiral‐stub‐loaded QMSIW resonator, respectively. Miniaturization is achieved by loading stubs and applying quarter‐mode cavities. High selectivity can be realized by introducing two transmission zeros (TZs) between the two passbands. One TZ is generated by adding coplanar waveguide coupling between the two resonators, the other TZ is synthesized by coupling between the modes of the resonator. The proposed dual‐band filter has the characteristics of miniaturization, high selectivity, and low loss, which is suitable for satellite communication related applications.

Coupling suppression study of miniaturized BDS/GPS multifunctional transceiver antenna based on quarter-mode substrate integrated waveguide

In this paper, a miniaturized BDS/GPS multifunctional antenna based on quarter-mode substrate integrated waveguide (QMSIW) is designed. Firstly, the dimension of the antenna is significantly reduced by using QMSIW technology. Secondly, the bandwidth of the antenna unit is widened by applying the multimode resonance theory. Thirdly, the four units are rotated and placed orthogonally with a reasonable layout to reduce the isolation between the units. Finally, the four units operating at 1268/1575/1616/2492 MHz are grouped in the array and loaded with the combined resonant structure to suppress the coupling between the units further. The designed antenna array covers the bands of BDS-2 B3, GPS L1, BDS-1 L and BDS-1 S, achieving 35 MHz (1255–1290 MHz), 50 MHz (1540–1590 MHz), 45 MHz (1605–1650 MHz) and 80 MHz (2480–2560 MHz) respectively, with the operating bandwidth and peak gain are 4.22, 5.68, 5.09 and 6.3 dBi. It is worth mentioning that after the decoupling process, the isolation degree between the antenna units is significantly improved. And the peak isolation degree between the four units finally drops to −34.3 dB (S12), −29.20 dB (S23 in GPS L1) and −30.29 dB (S23 in BDS-1 L) respectively.

BCB-Based Thin-Film Ka-Band Quarter-Mode SIW Packaged Filters With Ultrawide Stopband and Independently Controlled TZs

In this article, quarter-mode substrate-integrated waveguide (QMSIW) filters featuring ultrawide stopband and flexibly allocated transmission zeros (TZs) are proposed. Eight higher modes with resonant frequencies up to 4.7 times of the fundamental mode are highly suppressed. It is realized by the combination of three approaches without extra circuit areas. First, a slot is cut in the first and last QMSIW resonators to make their resonant frequencies of higher modes different from those of other resonators. Second, avoid exciting the specific higher modes by setting the feed point in the area where the electric field strength of the higher modes is weak. Third, mismatch the higher modes when matching the passband. It is realized by using a stripline impedance transformer with its main body not exceeding the area of QMSIW resonators. Furthermore, except for the TZs derived by the classical cross-coupling matrix, two more independently controlled TZs are generated. The packaged filter is fabricated by using a benzocyclobutene (BCB)-based microelectromechanical systems (MEMS) process, which is suitable for millimeter-wave 3-D system-on-package (SOP) applications. The fabricated thin-film filter is measured with an insertion loss of 2.96 dB at 29.4 GHz and a fractional bandwidth (BW) of 17%. Higher mode suppressions up to 138.3 GHz are achieved.

Design of Dual-Band, 4-Ports MIMO Antenna-Diplexer Based on Quarter-Mode Substrate Integrated Waveguide

Here, a compact, dual band, 4-elements multi-input and multi-output (MIMO) antenna diplexer is designed to use in wireless local area network (WLAN) applications. The antenna is accomplished in a planar profile by employing Substrate Integrated Waveguide (SIW) technology. To reduce the size of a single element by 75%, a quarter-mode substrate integrated waveguide (QMSIW) technology is introduced. The QMSIW is realized by bisecting the full-mode SIW along the two magnetic walls and considering the quarter-mode for the operation. Initially, two-QMSIW cavities of distinct dimensions are designed to operate in two frequency bands, 5.2 GHz and 5.8 GHz, respectively. Later, two more radiating elements operating at the same frequencies are integrated with a 2-elements antenna. For better polarization decoupling, the identical elements are placed perpendicular to each other, and a parasitic metallic strip loaded with shorting vias is placed between two identical frequency antenna elements; hence, the port isolation is improved up to −25 dB. The antenna covers a bandwidth of 1.8% in the lower frequency band while 2.2% in the upper frequency band. The antenna prototype is fabricated, and its results are verified with experimental data. It is observed that the measured results are closely following the simulated results.

Low-Profile VHF Antenna Based on Quarter-Mode Substrate-Integrated Waveguide Structure

A traditional whip antenna is suitable for terrestrial wireless communication due to its omnidirectional radiation pattern which is capable of transmitting and receiving signals from all directions. However, the length of a whip antenna is long for the very high frequency (VHF) band applications; for example, the ideal length is 80 cm at 90 MHz, which restrains the mobility when mounted on a vehicle. Many studies have been conducted to develop a low-profile antenna that can substitute a whip antenna but most of them are for relatively high frequency (GHz) applications. In this paper, a planar low-profile antenna operating in the VHF band is proposed. The height of the antenna is only 9 cm by utilizing a quarter-mode substrate-integrated waveguide (QMSIW) structure with shorting pins at the edges. The latter promotes omnidirectional radiations despite its short height. The antenna design was optimized by 3D full-wave simulation software. Subsequently, an antenna prototype was fabricated and tested. The results demonstrated that the antenna resonated at 86 MHz with a maximum gain of 1.7 dB along the azimuth direction.

Miniaturized Quarter-Mode SIW Filters Loaded by Dual-Mode Microstrip Resonator With High Selectivity and Flexible Response

A novel miniaturized multilayer quarter-mode substrate integrated waveguide (QMSIW) filter with high selectivity and wide stopband is proposed. First, an innovative multilayer dual-mode microstrip resonator is proposed to couple the QMSIW resonators located at the upper and lower substrate layers. The combination of the dual-mode resonator with the two QMSIW cavities leads to a fourth-order filtering response. Then, the coupling iris is opened at the position, where the magnetic field distribution in the QMSIW cavity achieves a peak value. Finally, sharp skirt is obtained by composing the modified box-like topology. In addition, different responses could be achieved by changing the position of the coupling iris, resulting in a wide stopband and flexible response. The size of the filter is also reduced through the multilayer QMSIW configuration and miniaturized multilayer dual-mode microstrip resonator.

A shielded QMSIW ultra-compact self-diplexing antenna for WiMAX/WLAN applications

In this contribution, novel design is presented for a very compact shielded quarter-mode substrate-integrated waveguide (S-QMSIW) based self-diplexing antenna (SDA) for WiMAX/WLAN applications. In order to achieve dual-band features, a slot is etched onto the top of the metal. Two orthogonal microstrip feed lines in the full-wave EM-simulator (HFSS) simulate the S-QMSIW resonator at two different frequencies (3.45 and 5.45 GHz). The proposed antenna pattern is extremely adaptable, allowing for simple frequency adjustments for each resonant frequency. A lumped circuit model is expected to be used to assess the antenna structure. A self-diplexing antenna based on S-QMSIW was designed, fabricated and tested to claim the proposed concept. At 3.45 and 5.45 GHz, the proposed antenna peak gains are 4.7 and 5.6 dBi, respectively. It offered port isolation better than 38 dB. The antenna front-to-back ratio was greater than 19.5 dB in each band. The proposed antenna circuit size was very compact ().

A W-Band Compact Substrate Integrated Waveguide Bandpass Filter With Defected Ground Structure in CMOS Technology

This brief proposes the first on-chip bandpass filter (BPF) based on substrate integrated waveguide (SIW) for W-band applications. Slot-loaded, folded ridge and quarter mode technology is used to reduce the cavity size. The coupling characteristic of two folded ridged quarter mode substrate integrated waveguide (QMSIW) cavities implemented in CMOS technology is investigated. A simplified equivalent lumped-element circuit model of the proposed wide-band BPF approach is provided and applied to study the coupling characteristic of slot-loaded folded ridged QMSIW cavity. Then, a novel coupling method using a defected ground structure is proposed to realize a proper coupling intensity for BPF design. Finally, the proposed BPF design is implemented in a commercial complementary metal-oxide-semiconductor (CMOS) technology, fabricated, and measured. The active size of the proposed cavity resonator is only 405 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times185\,\,\mu \text{m}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.22{\lambda }_{\mathrm{ g}} \times 0.1 \lambda _{\mathrm {g}}$ </tex-math></inline-formula> ), and the measured insertion loss ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert|\text{S}_{21}~\vert|$ </tex-math></inline-formula> ) is 3.15 dB with a central frequency of 85.5 GHz.

Highly-Miniaturized Dual-Mode Bandpass Filter Based on Quarter-Mode Substrate Integrated Waveguide With Wide Stopband

This paper presents a novel design of a highly-miniaturized dual-mode bandpass filter (BPF) employing a quarter-mode substrate integrated waveguide (QMSIW). The QMSIW resonator is based on a square cavity with metallic vias along two sides, and open-ended edges at the remaining sides that contain orthogonal feed lines. An open slot is introduced along the two sides of the square cavity with metallic vias to form a magnetic wall. A single metallic via is assigned at the corner of the two open-edged sides to form an electrical wall, which produces different resonances. By loading a slot diagonally, the mode frequencies can be controlled independently, which allows us to realize a second-order BPF. The detailed design steps and a flowchart explaining the filter’s topology evolution are presented. The eigen-mode analysis, field distributions, coupling matrix, and full-wave simulation of the proposed QMSIW filter topology are used to determine the filter’s operating principle. To verify the proposed theory, a second-order BPF is realized, fabricated, and demonstrated experimentally. The BPF prototype exhibits excellent performance such as a small footprint of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.019\lambda ^{2}$ </tex-math></inline-formula> , a wide passband of 34.8-percent, low insertion loss of 0.43 dB, and a wide stopband of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.36f_{0}$ </tex-math></inline-formula> with a rejection level greater than 20 dB. Excellent consistency is found between the EM-simulated and measured responses of the device.

Planar High-Isolation Dual-Band Dual-Mode Antenna With Omni-/Unidirectional Radiation

A planar dual-band dual-mode antenna with omni-/unidirectional radiation is proposed for 2.45/5.8 GHz bands. The lower-band antenna consists of four modified quarter-mode substrate-integrated waveguide elements, which are excited in-phase and with same magnitude to obtain vertically polarized omnidirectional radiation. The upper-band antenna is based on a four-port square patch with differential feeds to achieve highly isolated dual polarization with broadside radiation. In addition, the square patch is loaded with four overlapped-corner-mushroom structures to broaden the upper bandwidth. The final design with an overall size of 90 × 90 × 3.66 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^3$</tex-math></inline-formula> (0.735 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> × 0.735 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> × 0.03 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\lambda$</tex-math></inline-formula> at 2.45 GHz) was fabricated and measured. The measurements show a 10-dB return loss bandwidth of 160/400 MHz and a gain of 3.4/8.5 dBi at 2.45/5.8 GHz bands, respectively. Furthermore, the antenna prototype demonstrates an isolation of more than 30 dB among all ports. Especially, the isolation among the two ports of the upper-band elements is better than 40 dB.

Cavity Backed Multiband SIW Antenna for X Band Applications

This article designs, tests, and produces a substrate integrated waveguide based antenna with copper patches in the micro strip in a totally planar construction utilising microstrip technology. The performances of this SIW antenna, as well as geometrical antenna aspects, are investigated in the X-band at frequencies ranging from 5 to 10 GHz. The efficiency and directivity of the substrate integrated waveguide antenna have been improved, and the side lobe level has been increased, making it highly promising. SIW technology seems to be the most viable option for millimeter-wave integrated circuits and systems in the next decade. This article gives an overview of SIW technology research in academia and industry, as well as its current state and future potential. The development of numerical tools for SIW component modelling and design, as well as the investigation of new compact and broadband interconnects and the discovery of design solutions for loss reduction, are all current research priorities. It consists of two connected quarter-mode SIW resonant cavities and one half-mode SIW resonant cavity. This groundbreaking technology combines a considerable bandwidth boost with a tiny footprint and existing PCB manufacturing procedures at a cheap cost, making it ideal for 5G high-speed wireless applications. SIW technology provides a robust antenna basis, enabling for the integration of high-density active electronics without the possibility of damaging coupling.

Bandpass frequency selective surface with two sharp sidebands based on shunted quarter‐mode substrate integrated waveguide cavities

AbstractA new highly selective bandpass frequency selective surface (FSS) is proposed with sharp sidebands and low profile. The unit element is composed of two shunted quarter‐mode substrate integrated waveguide (QMSIW) cavities with different dimensions and L‐shaped slots etched on both sides of dielectric substrates. Two transmission zeros and three transmission poles are obtained by TM0.5,0.5,0 resonance of cavities, slot resonance, and the coupling between them, which yield a flat passband with steep roll‐off in both sidebands. As unit dimension is miniaturized using quarter‐mode resonance, the FSS presents good angular stability for dual polarization. Simulated results indicate that the passband with insertion loss less than 1 dB covers 8.86–9.57 GHz, while the transitional bandwidth at both sides of the passband is 27 and 25 MHz, respectively. A prototype was fabricated and measured, the experimental results of which verified the design.

Compact filtering power divider using mixed quarter‐ and eighth‐mode substrate integrated waveguide resonant cavities with flexible design

In this paper, a series of filtering power dividers (FPDs) employing quarter-mode substrate integrated waveguide (QMSIW) and eighth-mode substrate integrated waveguide (EMSIW) resonant cavities have been first demonstrated. The proposed prototypes possess the merits of extremely miniaturized dimensions and relatively low insertion loss. Based on the detailed analysis and investigation of electromagnetic features and feeding types corresponding to the miniaturized SIW resonant cavities, two-order mixed QMSIW and EMSIW FPDs with electric coupling or magnetic coupling topologies are presented. In addition, multi-layered structures are implemented to decrease the footprints of the FPDs further. To attain a higher-order design and enhance the out-of-band rejection, a four-order multi-layered FPD with cross coupling mechanism is finally developed. For demonstration and verification, seven prototypes of the proposed FPDs operating at 4.8 GHz are meticulously designed, fabricated, and measured. All experimental results are in reasonable agreement with the simulated ones.

Five‐way radial filtering power divider using back‐to‐back quarter‐mode substrate‐integrated waveguide and microstrip resonator

This paper proposes a five-way filtering power divider (FPD) based on a back-to-back quarter-mode substrate-integrated waveguide (QMSIW) and microstrip resonator. The FPD is composed of two layers of the dielectric substrate. Back-to-back QMSIWs and microstrip resonators are designed on the dielectric substrate 1. On the dielectric substrate 2, the SIW circular cavity is excited by a coaxial probe to realize the power dividing function and is coupled with QMSIWs through five rectangular slots. The measurement results show that the minimum insertion loss of the FPD is 1.2 dB at 9 GHz, the measured functional bandwidth is 4%, and the stopband attenuation from 10 to 19.8 GHz is better than 35 dB, the stopband attenuation at frequencies below 8.3 GHz is greater than 45 dB.