Ridge Gap Waveguide Technology Research Articles

Circularly Polarized Ka-Band High-Gain Antenna Using Printed Ridge Gap Waveguide and 3-D-Printing Technology

A low cost high gain circularly polarized antenna is proposed, the proposed antenna achieves a gain of 20-dBi, and an axial ratio bandwidth of 6.5%. The proposed antenna is extremely low in cost as it uses Printed Ridge Gap Waveguide (PRGW) technology. The use of PRGW technology suppresses the parasitic and back-lobe radiation from the feed, which maintains neat radiation characteristics for the radiating antenna. The structure is made of a Magneto-Electric (ME) dipole which illuminates a set of adjacent dielectric slabs. The diffracted fields from the edges of the dielectric slabs add up constructively with the ME dipole radiated fields in the boresight, and boost the gain of the ME dipole. Accordingly, the antenna structure relaxes the need for designing a feeding network by utilizing the diffracted fields from dielectric slabs edges. A 3D printed dielectric polarizer is used to further boost the gain and transform the polarization of the antenna to circular polarization. The antenna possesses a focused pencil-beam pattern that is well-suited for several mm-wave applications.

A Novel Low‐Loss Planar PRGW Crossover Design for 5G Applications

AbstractIn this paper, a planar 0‐dB crossover using printed ridge gap waveguide (PRGW) technology is proposed and designed for millimeter‐wave applications. PRGW as a quasi‐TE mode is considered as the modern guiding technology at high frequencies and for the 5G and other upcoming communications. A prototype of the proposed PRGW crossover working around 30 GHz is fabricated and measured to validate the simulated results. Comparing simulated with measured results, a good agreement is observed. The measured results demonstrate that the designed crossover offers an insertion loss of better than 0.5 dB over the whole operating frequency bandwidth from 29 to 31 GHz where the return loss level is better than 15 dB and the isolation level is less than −13 dB. Compared with the other reported crossover structures, the designed PRGW crossover features a wider bandwidth with a smaller and planar configuration.

A low insertion loss wideband mm-Wave crossover with three-section branch-line structure based on ridge gap waveguide technology

In this paper, a low insertion loss (IL) wideband millimeter wave (mm-Wave) crossover with three-section branch-line structure based on ridge gap waveguide (RGW) technology is proposed. Firstly, the central-crossover is designed, especially two types of tuning pins are introduced, which greatly improves the performance of the crossover. In addition, in order to facilitate the measurement, the transition from rectangular waveguide (RWG) to RGW is designed. Finally, a prototype is manufactured and measured. The simulation results show that in the frequency range of 28.9 GHz to 36.6 GHz, RL is better than 20 dB, while the isolation levels of |S21|, |S41|, and |S43| are lower than −20 dB, −10 dB, and −20 dB over the same band, respectively. IL is below 0.5 dB in the frequency range of 28.15 GHz to 36.65 GHz. Good consistency was observed between the simulation results and the measurement results.

Broadband Three-Section Branch-Line Coupler Realized by Ridge Gap Waveguide Technology From 12 to 20 GHz

Broadband Three-Section Branch-Line Coupler Realized by Ridge Gap Waveguide Technology From 12 to 20 GHz

High Gain Fan-Beam Pattern Antenna Based on the Utilization of Diffracted Fields From Dielectric Slabs Edges for IoT and Sensing Applications

A high gain, low-cost antenna structure is designed for a smart car parking system. The antenna uses Printed Ridge Gap Waveguide (PRGW) technology, which is fully shielded, and suppresses any parasitic radiation from the feed, and minimizes back-lobe radiation. The proposed antenna uses a single MSL feed point, which eliminates the need for any complex feeding network design, and allows the antenna to be integrated easily with PCB transceiver circuitry. A novel technique for the design procedure is proposed, the technique provides a generalization of using either electric or magnetic excitations with dielectric or magnetic rectangular slabs. A unique physical insight accompanied with a thorough analysis of the propagation mechanism is provided. The technique has a significant impact on reducing the complexity of the feeding network. The realized structure is compact, low profile, and low cost. The beam pattern of the antenna is a Fan-Beam (Elliptical) pattern which is well suited for various sensing and Internet of Things (IoT) applications.

Broadband millimeter-wave metasurface antenna array with printed ridge gap waveguide for high front-to-back ratio

A novel broadband metasurface (MTS) antenna array with high front-to-back ratio (FBR) is proposed for 28 GHz millimeter-wave applications. With slot pairs loaded on patch cells, an aperture-coupled slotted-mushroom MTS antenna is designed to obtain broadband radiation characteristics with a compact size. To suppress the backward radiation of this antenna, the printed ridge gap waveguide (PRGW) technology with a perfect magnetic conductor (PMC) shielding made of mushroom unit-cells underneath the microstrip feeding line is applied. On this basis, a 4 × 4 MTS antenna array with the PRGW feed network is developed. Simulated results show that the FBR can be highly improved by over 16 dB within the entire bandwidth. To validate the design, a prototype of the proposed antenna is fabricated. Measured results show that an FBR greater than 28 dB can be obtained over a 24% impedance bandwidth (from 24.9 GHz to 31.7 GHz) with the reflection coefficient less than −10 dB. The measured antenna gain ranges from 17 dBi to 19.2 dBi and the corresponding measured aperture efficiencies are 35% and 45.6%. The measured results also suggest that the proposed MTS antenna possesses −35 dB cross-polarization level and stable radiation patterns. In addition, the proposed antenna remains a very low profile of 1.7 mm (0.17λ0 at 28 GHz). All the achieved features indicate that the proposed MTS antenna is an important candidate for B5G and 6G wireless communication.

Design of an E-sectoral horn based on PRGW technology for 5G applications

AbstractE-plane sectoral horn antenna based on printed ridge gap waveguide (PRGW) technology is designed for 5G applications. It is implemented on the top plate of the PRGW structure to avoid the losses and dispersion associated with conventional feeding mechanisms. The quasi-transverse electromagneticPRGW-based antenna is excited through a planar microstrip transition. First, the single horn antenna element is introduced with the microstrip feeding section. It shows an impedance bandwidth of fractional bandwidth 26% from 45.7 to 55.4 GHz with the realized gain of 12.7 dBi and radiation efficiency of 90%. In order to maximize the realized gain, a four-element linear horn array is introduced. The same impedance bandwidth is maintained with the array having a gain of 18.6 dBi from 45.7 to 55.4 GHz. The overall antenna array performance in the entire operating frequency range is stable with a radiation efficiency around 85%. Three matching sections are implemented to achieve better impedance matching. One is used to match the horn with the feeding aperture via the PRGW line. Another section is designed to match microstrip transition with PRGW ridge. Finally, two-stage quarter wavelength transformers are required to match the power divider with the array feeding network. A prototype of single-element horn antenna was fabricated to verify the concept of the design. Simulated and measured results show that the proposed antenna can operate in the frequency band of 45–55 GHz with good agreement of radiation performance. Moreover, the proposed designs are implemented and simulated using two microwave simulation tools (CST and HFSS) to verify the radiation performance, which exhibits good agreement. The design of an E-sectoral horn antenna and its array with high gain based on PRGW is demonstrated for the first time which is considered a novel issue. It can be integrated with other passive and active elements in communication systems. Thus, it can be a valuable component in 5G communication due to its high gain, compact size and ultra-wide band.

Dual circular polarization 2 × 2 slot array antenna based on printed ridge gap waveguide technology in Ka band

In this paper a novel multi-layer slot array antenna based on printed ridge gap waveguide (PRGW) technology with dual circular polarization (CP) at Ka band is proposed. This antenna consists of five layers, two dielectric substrates as a transition from PRGW to coax line and a branch line coupler (BLC) as an antenna feeding network, and three metal layers as a coupling slot, 2 × 2-element slot array antenna and ground layer. Feeding network has two individual ports consists of a BLC that based on PRGW implemented. The operating frequency band of the antenna for S11 < −10 dB with the gain more than 11.5 dBi is 27–29 GHz which covers the 27.5–28.35 GHz band proposed by Federal Communications Commission (FCC) and can be a suitable antenna for 5G applications at this frequency band. Total aperture size of the array antenna is less than 1.15 × 1.15 λ2 at 28 GHz and total efficiency of it is better than 80 %. Two individual ports of the proposed antenna provide two isolated left- and right-hand CP with axial ratio (AR) less than 2 dB for each port in aforementioned frequency range, and the measured results indicated that the antenna can provide isolation more than 15 dB between two input ports.

Differentially Fed Dual-Polarized 2-D Multibeam Dielectric Resonator Antenna Array Based on Printed Ridge Gap Waveguide

In this article, a differentially fed dual-polarized dielectric resonator antenna (DRA) subarray excited by a substrate integrated waveguide (SIW) cavity is proposed. A #-shaped slot etched on the top wall of the SIW cavity is used to achieve the differential excitation due to the intrinsic field distribution of TE120 mode in the SIW. Based on the proposed antenna subarray, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> 2 dual-polarized 2-D multibeam DRA antenna array with simple structure is designed, fabricated, and measured, which can achieve high cross-polarization discrimination (XPD) in the direction of maximum radiation. To reduce substrate loss, the printed ridge gap waveguide (PRGW) technology is used to feed the SIW cavity. Two orthogonal PRGW Butler matrices are placed at different layers so as to realize 2-D beamforming scanning with dual-polarization. The SIW cavity is placed in the air gap of PRWG, which can increase the stability of the antenna structure. By cleverly combining the SIW cavity and PRGW structure, the proposed multibeam antenna array has the advantages of high XPD and high radiation efficiency. Measured results show that an impedance bandwidth of 10% (28.5–31.5 GHz) and a peak gain of 11.8 dBi are obtained. Also, the measured XPDs are 28.3 dB at the center frequency and larger than 19.2 dB over the band of operation. Besides, the measured radiation efficiency of 67% is achieved for both the polarizations at 30 GHz.

Dispersion Analysis of Periodic Structures in Anisotropic Media: Application to Liquid Crystals

This paper presents an efficient method to compute the dispersion diagram of periodic and uniform structures with generic anisotropic media. The method takes advantage of the ability of full-wave commercial simulators to deal with finite structures having anisotropic media. In particular, the proposed method extends the possibilities of commercial eigenmode solvers in the following ways: (i) anisotropic materials with non-diagonal permittivity and permeability tensors can be analyzed; (ii) the attenuation constant can easily be computed in both propagating and stopband regions and lossy materials can be included in the simulation; and (iii) unbounded and radiating structures such as leaky-wave antennas can be treated. The latter feature may be considered the most remarkable, since the structures must be forcefully bounded with electric/magnetic walls in the eigensolvers of most commercial simulators. In this work, the proposed method is particularized for the study of liquid crystals (LCs) in microwave and antenna devices. Thus, the dispersion properties of a great variety of LC-based configurations are analyzed, from canonical structures, such as waveguide and microstrip, to complex reconfigurable phase shifters in ridge gap-waveguide technology and leaky-wave antennas. Our results have been validated with previously reported works in the literature and with commercial software CST and HFSS.

A flexible low insertion‐loss wideband millimeter‐wave crossover based on ridge gap waveguide technology

This paper presents a flexible low insertion-loss wideband millimeter-wave crossover based on the ridge gap waveguide (RGW) technology. Based on the design of periodic metal pins of gap waveguide (GW), the transmission modes in the ridge have been analyzed in detail. The influence of different widths of the ridge on the cutoff frequency of the quasi-TEM mode and the first high-order mode in GW are mainly discussed. According to the results of the mode analysis, a flexible wideband low insertion-loss central-crossover covering 42–51 GHz is designed, which can be easily used to form the Butler Matrix (BM). Furthermore, a transition from standard rectangular waveguide to RGW has been designed. Finally, to validate the proposed design method, a complete crossover prototype based on RGW technology operating from 42 to 45.5 GHz in U-band is designed and fabricated. The measured results have a good agreement with simulated results.

Ridge Gap Waveguide based band pass filter for Ku-band Application

This paper describes a simple, low loss, compact tuneable band pass filter based on ridge gap waveguide (RGW) technology for the Ku-band applications. This is achieved by keeping the height of the air gap in the gap guide structure equal to the thickness of the substrate or base of the structure. The resonant frequency and electromagnetic (EM) field distribution of the structure is investigated. This filter is designed by inserting the proposed ridge in the cut-off region of the gap waveguide. The frequency of tuning has been carried out using the slot created on ridge, which generates capacitive effect. Experimental results of the manufactured structure show an insertion loss of approximately 0.15 dB and a return loss of 16.38 dB over 4.5% relative bandwidth in Ku-band. The structure, put forwarded here, has been designed and optimized in the CST microwave studio environment and simulated results are validated by experimental results. The size of the structure is 64.65 mm × 64.65 mm × 7 mm.

On the Use of Ridge Gap Waveguide Technology for the Design of Transverse Stub Resonant Antenna Arrays.

This paper presents some considerations on the design of a novel antenna consisting of the combination of a transverse stubs (TS) array excited by Ridge Gap Waveguides (RGWs), as well as a discussion of the experimental results obtained from a prototype that was manufactured and measured. A combination of Continuous Transverse Stubs (CTSs) is used as the starting point. Subsequently, the CTSs are modified to include some metallic blockers that split each CTS into a combination (array) of shorter TSs. This is performed in order to excite each individual TS column using a different RGW; thus, ensuring a close to uniform field distribution in the transverse plane of the TS arrays. Hence, the directivity of the antenna is increased. As a series-feed configuration is considered, the antenna keeps a resonant behaviour, having a narrow-band response. A Corporate Feeding Network (CFN) using the aforementioned RGW technology placed in the same layer as the rest of the antenna is included in the design. The radiating area of the antenna is, finally, with a simulated peak gain of 26.2 dBi and a Side Lobe Level (SLL) below −13 dB. A prototype is manufactured and tested. The simulated and measured radiation patterns maintain similar shapes to those of the simulations, with very similar angular widths in both main planes, although the frequency corresponding to the highest directivity changes to 31.8 GHz. A matching bandwidth of 517 MHz and a gain of 24.5 is, finally, achieved at that frequency.

A High-Efficiency Zeroth-Order Resonant (ZOR) Antenna Fed by Printed Ridge-Gap Waveguide Technology

In this paper, a zeroth-order resonator (ZOR) antenna fed by a printed ridge gap waveguide (PRGW) is reported for 5G/6G applications in millimeter-wave bands. A zeroth-order resonance (ZOR) order technique with omnidirectional pattern feature is incorporated into a slot antenna to increase the coverage area of the slot antenna with high gain and directive pattern. The proposed antenna supports a high radiation efficiency and stable high coverage directional gain characteristic.

Ku-band 8-way Wilkinson power divider based on ridge gap waveguide technology

The novel ridge-gap waveguide (RGW) technology which has recently been introduced has many advantages in micro/mm-wave frequencies such as low loss, broad bandwidth, low sensitivity to manufacturing errors and easy integration with active components, etc. In this paper, a Ku-band 8-way Wilkinson power divider (WPD) is proposed and simulated based on the RGW technology for the first time, to the best of our knowledge. An RGW-toWR62 transition is also designed and simulated. The proposed 8-way RGW-based WPD with WR62 transitions shows low-loss equal-power division in phase with good matching at all ports and isolation between output ports in the Ku band. The proposed RGW-based WPD can be extended to an arbitrary -way corporate power divider/combiner which can find many applications such as in array antenna feed networks, solid-state power amplifiers (SSPAs), etc.

Ka‐band coupled‐resonator bandpass filter based on printed ridge gap waveguide for millimetre‐wave application

A low-loss Ka-band coupled-resonator bandpass filter based on the printed ridge gap waveguide (PRGW) technology is presented for millimetre-wave communication applications. The PRGW is employed to allow electromagnetic-wave propagation in the air gap in order to avoid dielectric loss and improve transmission performance which is suitable for millimetre-wave applications. The bandpass filter is implemented with two transmission zeros which are easily obtained by adjusting the stub length of two T-shape stub-loaded resonators (SLR). From its simulation frequency response, the filter has an insertion loss of 0.8 dB, a return loss less than −20 dB during the passband and high selectivity in cut-off frequency. The prototype of the proposed filter is fabricated and tested and a good agreement can be observed between the measured and simulated results.

Systematic Design Procedure for Y-Junction Circulator Based on Ridge Gap Waveguide Technology

A Y-junction circulator based on the ridge gap waveguide (RGW) as a hosting guiding structure is designed using a developed closed-form systematic procedure. To validate the structure, an air-filled-to-dielectric-filled transition is proposed using a substrate perforation technique. The proposed RGW circulator covers the whole Ku-band with a matching bandwidth throughout the operational bandwidth below -15 dB. A prototype is fabricated and tested, providing a satisfactory agreement with the simulated results.

Bagley polygon power divider realized by ridge gap waveguide technology

AbstractThe novel ridge‐gap waveguide (RGW) technology which uses a full metal structure has many advantages in micro/mm‐wave frequencies such as low loss, broad bandwidth, low sensitivity to manufacturing errors, and easy integration with active components, and so forth. In this paper, a Ku‐band 3‐way Bagley polygon power divider (BPD) is proposed and experimentally demonstrated based on the RGW technology for the first time, to the best of our knowledge. An RGW‐toWR62 transition is also designed and fabricated. The proposed three‐way RGW‐based BPD with WR62 transitions shows low‐loss equal‐power division in phase with good impedance matching and isolation between output ports in the Ku band. The proposed RGW‐based BPD can be extended to an N‐way power divider.

Gysel Power Divider Realized by Ridge Gap Waveguide Technology

The novel ridge-gap waveguide (RGW) technology which uses a full metal structure has many advantages in micro/mm-wave frequencies such as low loss, broad bandwidth, low sensitivity to manufacturing errors, and easy integration with active components, etc. In this paper, a Ku-band Gysel power divider (GPD) is proposed and experimentally demonstrated based on the RGW technology for the first time, to the best of our knowledge. An RGW-to-WR62 transition is also designed and fabricated. The proposed RGW-based GPD with WR62 transitions shows low-loss equal-power division in phase with good impedance matching and isolation in the Ku band. The measured results are in good agreement with the simulations. Besides, it is shown that the proposed structure can be used as a 3-way GPD with an unequal power splitting ratio. The proposed RGW-based GPD can be extended to a 2N-way power divider which can find applications in solid-state power amplifiers, array antenna feed networks, etc.

Analysis of the Propagation Constant of a Ridge Gap Waveguide and Its Application of Dual-Band Unequal Couplers

In this article, an analysis of the propagation constant and the characteristic impedance of a ridge gap waveguide (RGW) is proposed, which includes the comparison of the phase variation between three kinds of guiding structures, the approximation for the propagation constant of RGW, and the variation of characteristic impedances and phase characteristics. According to the analysis, the RGW technology, rather than the traditional microstrip transmission line, is utilized to implement two dual-band unequal couplers operating at two frequency bands. Furthermore, a coupler is fabricated and measured, exhibiting a dual-band operation with a power-dividing ratio of 2 dB and a quadrature phase difference with the same sign between two output ports.