Printed Ridge Gap Waveguide Technology Research Articles

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.

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.

Wideband 4 × 4 Butler Matrix in the Printed Ridge Gap Waveguide Technology for Millimeter-Wave Applications

A wideband printed ridge gap waveguide $4\times 4$ Butler matrix at 30 GHz is presented. The printed ridge gap technology is used as it has very low losses and supports the propagation of quasi-TEM mode. Each component of the Butler matrix has been designed and analyzed where a superior performance is achieved in terms of bandwidth and size. The designed components are combined to form the Butler matrix. The Butler matrix has a wideband performance where the return loss and isolation levels are higher than 10 dB in the frequency range from 26.9 to 33.3 GHz, the output amplitude imbalance is ±1.6 dB, and the phase error is ±10°. The measured radiation patterns are in a good agreement with the simulated ones, beam directions are at ±13° and ±36° at the center frequency. The gain is ranging from 10.2 to 11.35 dBi for excitation from port 1 and ranging from 8.4 to 10.2 dBi for excitation from port 2.

A Dual-Polarized Magneto-Electric Dipole Antenna Based on Printed Ridge Gap Waveguide Technology

In this communication, a dual-polarized magneto-electric (ME) dipole antenna is implemented in the printed ridge gap waveguide (PRGW) technology. The antenna is composed of a cross-shaped ME-dipole backed by an artificial magnetic conductor (AMC) sidewall cavity. This cavity is fed by two orthogonal PRGWs implemented in two separate layers to achieve a dual-polarization with −28 dB isolation level at the center operating frequency (30 GHz). The proposed antenna achieves a 23.4% relative impedance bandwidth at 30 GHz with isolation better than 20 dB over the whole operating frequency band. In addition, a gain enhancement technique is used to increase the gain to 10 dB over the operating bandwidth. A prototype is fabricated and there is a good agreement between simulated and measured results.

Design of High-Selective Printed-Ridge Gap Waveguide Filter Using Source–Load and Cross Couplings

In this letter, high-selective bandpass filters, in the printed ridge gap waveguide technology, are presented. The filters are designed to perform 4.68% fractional bandwidth at center frequency $f_{0}$ = 24.78 GHz. In the proposed filters, to obtain high selectivity, a cross-coupling between the nonadjacent resonators and also a coupling between the input and output ports to create an extra pair of transmission zeros in the transfer function of the filters are used. Finally, the filters are fabricated, and their scattering parameters are measured to verify the simulation results.

A Dual-Polarized Magnetoelectric Dipole Array Based on Printed Ridge Gap Waveguide With Dual-Polarized Split-Ring Resonator Lens

In this article, a 1x4 dual-polarized magnetoelectric (ME) dipole antenna array is proposed. The antenna is excited by a dual-polarized fork-shaped microstrip line based on printed ridge gap waveguide technology. To achieve additional gain, a dual-polarized split-ring resonator (SRR) is designed, which has a mu-near zero (MNZ) feature. This scatterer works as a meta-lens to convert the radiated spherical wave to a plane wave for both polarizations. Integrating four layers of the proposed inclusions on top of the ME dipole antenna results in an increase in the antenna gain by a maximum of 3 dB. The proposed 1 x 4 antenna array was fabricated and tested, and the measured reflection coefficient at Port 1 is less than -10 dB over the frequency band of 28-35 GHz, while the measured realized gain varies from 14.3 to 15.4 dBi, and the measured radiation efficiency varies from 78% to 88%. The measured reflection coefficient at Port 2 for the orthogonal polarization is less than -8 dB over the frequency band of 28-35 GHz, with a measured gain of 14.8-16 dBi, and the measured radiation efficiency varies from 81% to 90%.

Wideband Printed Ridge Gap Rat-Race Coupler for Differential Feeding Antenna

In this paper, a wideband 3 dB hybrid 180° rat-race coupler is introduced in the printed ridge gap waveguide technology. It has simultaneous wide matching and isolation bandwidth with low output amplitude imbalance. It operates in the millimeter wave band from 25.8 to 34.2 GHz (27.96%) with 15 dB return loss and isolation, and ±0.5 dB output amplitude imbalance. The proposed design employing an open stub at the middle of the $3 \lambda /4$ branch line and quarter wavelength lines at all the ports of the coupler. The objective of the added open stub is to separate the output ports amplitudes around the -3 dB level by certain values depending on the required amplitude imbalance. The analytical derivation for the role of the added open stub is presented along with a parametric study on its effect on amplitude imbalance, matching, and isolation. This results in having two intersection points for the output ports instead of one of the conventional coupler and hence the amplitude imbalance bandwidth increases. The objective of the added quarter wavelength lines is to improve the matching and isolation bandwidths. First, the conventional rat-race coupler is presented and a bandwidth of 14.25% at 30 GHz is achieved. After that the rat-race with the added quarter wavelength lines is presented to illustrate the objective of the added quarter wavelength lines and a bandwidth of 19.44% is achieved. Finally, the rat-race with the quarter wavelength lines and the added stub is presented and a prototype is fabricated and measured. The s-parameters measurements are in a good agreement with the simulated ones.

Printed RGW Circularly Polarized Differential Feeding Antenna Array for 5G Communications

In this paper, a differential feeding circularly polarized antenna array implemented with printed ridge gap waveguide technology for millimeter-wave applications is proposed. The differential feeding power divider is designed based on aperture coupling to achieve a stable 180° phase imbalance over 20% operating bandwidth at 30 GHz with sufficient matching level. This power divider is deployed to excite and test the proposed differential feeding antenna. The proposed antenna is formed by a rectangular aperture having a circular-shaped polarizer consisting of patch surrounded by an open-end ring, which is differentially fed. This polarizer is deployed to achieve a circular polarization radiation through a 10 % frequency bandwidth. A high-gain antenna array is implemented by extending the aperture size to have four radiating elements. The antenna array is fabricated, where the experimental results verify a −10 dB impedance bandwidth from 27.7 to 32.4 GHz (15.6%). Moreover, a 3 dB axial ratio bandwidth over 10 % is achieved, which is sufficient enough to cover the operating bandwidth of potential 5G applications at 30 GHz. The fabricated prototype achieves a 3 dB gain of 14 dB, with low cross polarization and a radiation efficiency higher than 84% over the whole operating frequency bandwidth.

Ultra‐wideband printed ridge gap waveguide hybrid directional coupler for millimetre wave applications

The evolution of a wireless communication system to the fifth generation is accompanied by a huge improvement in the performance of the communication system through providing high data rate with a better coverage area. Hence, 5G technology requires access to millimetre wavebands where more spectra are available for high-speed applications. This technological progress motivates the research community to develop the essential microwave components, specially couplers, through the use of state of the art guiding structure such as printed ridge gap waveguide (PRGW). In this study, the design of ultra-wideband 3-dB planar quadrature hybrid coupler based on PRGW technology is proposed. A systematic design procedure for the proposed coupler is presented and illustrated. The proposed directional coupler is fabricated and measured, where the measured results show good agreement. The presented coupler covers over 26% bandwidth centred at 30 GHz. The presented coupler has a measured wide impedance bandwidth of a 26.5% centred at 30 GHz based on -10 dB threshold. The phase difference between output ports is 90° ± °5 over 23% relative bandwidth. On the other hand, the total bandwidth is limited by the amplitude imbalance, which has a bandwidth of 13% for± 0.75 dB variation.

High Gain Bow-Tie Slot Antenna Array Loaded With Grooves Based on Printed Ridge Gap Waveguide Technology

The development of wireless and satellite communication has led to a demand for high-performance microwaves and mm-wave components in terms of cost, losses, and fabrication complexity. Gap waveguide is one of the emerging technologies in 5G and mm-wave applications due to their low cost, low losses, and high power handling capability. In this paper, a groove-based wideband bow-tie slot antenna array is designed at 30 GHz based on printed ridge gap waveguide technology (PRGW). A two-section T-shaped ridge is designed to feed a bow tie slot placed on the upper ground of the PRGW. The gain of the proposed slot antenna is enhanced by using a horn-like groove. Then, the proposed high gain element is deployed to build up a 1 bow-tie slot antenna array loaded with three-layer groove antenna. The proposed antenna array is fabricated and measured, where the measured results show a −10-dB impedance bandwidth from 29.5 to 37 GHz (22%). The fabricated prototype achieves a high gain of 15.5 dBi and a radiation efficiency higher than 80% over the operating frequency bandwidth.

Analytical Prediction of the Radiation Characteristics of $2\times2$ Ridge Gap Waveguide Slot Antenna Array With Suppressed Grating Lobes at the V-band

In this paper, the radiation patterns due to magnetic sources embedded in a ground plane in the presence of a partially reflective surface are analytically formulated and calculated. Love's equivalence principle, the transmission-line analogy, and the reciprocity theory are all combined and employed to calculate the far-fields of a four-element (2 × 2) slot array excited by the printed ridge gap waveguide technology operating in the V-band. Since the spacing between the array elements is greater than one wavelength, grating lobes cannot be avoided. Hence, to suppress the grating lobes and enhance the antenna directivity, a dielectric superstrate with the proper properties is utilized. The slot antenna array is operating at 60 GHz for millimeter-wave applications. The obtained results from the proposed analytical formulation agree very well with full-wave numerical simulations obtained from the EM commercial tool HFSS. It is worthwhile to mention that the presented analytical solution is about 30 times faster than its full-wave simulator counterpart.

Planar High-efficiency Antenna Array Using New Printed Ridge Gap Waveguide Technology

High-efficiency millimeter wave antenna array is proposed. A cooperate feeding network is designed using the new printed ridge gap waveguide technology, which is self-packaged with low loss. The feeding network is designed to couple to narrow slots arranged in a planar array that is coupled to printed broadband magnetoelectric (ME) dipoles. An array of $4 \times 4$ ME dipoles is designed. The simulated results are verified with measurements. The measured reflection coefficient is less than −10 dB over 16.5% bandwidth (28.8–34 GHz). The measured antenna gain is higher than 19 dBi, and the cross polarization measured gain is around −35 dB within the main beam. Furthermore, the measured total radiation efficiency is 70%, and the measured aperture efficiency corresponds to 90% at 30.2 GHz.