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E-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.

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.

The mismatch terminations are essential components in measurement setups of various active and passive microwave components. The main objective of such components is to provide a certain reflection level with a flat response over the operating bandwidth. The need for mm-wave mismatch terminations has increased due to the expansion of using mm-wave frequency ranges in future communication systems. The mm-wave bands are considered among the essential bands for the 5G communication system, which is expected to launch this year. In addition, the utilization of these bands is expected to increase in the 6G standard. In this article, we introduce a novel systematic procedure to design mismatch terminations. Moreover, two examples of mismatch terminations are designed with reflection levels of −9.5 and −12.7 dB, with the operating band of 32–38 GHz. For experimental validation, the proposed design is fabricated and measured, where a good agreement is achieved between the simulated and the measured response.

In this article, the design of full-band rectangular waveguide pressure windows for high power applications is presented. The proposed design features a compact size, low loss, and a simplified fabrication process. A short impedance step is deployed to achieve a deep matching level over the full band of the standard waveguide. An approximate circuit model is proposed to select the initial dimensions for the proposed design to reduce the design time frame. Despite the wide use of pressure windows in many applications, the need for an accurate model still exists. The proposed model has been validated over different rectangular waveguide standards through numerical simulations with a maximum mean square error of 3%. Based on the proposed model, standard WR90 and WR28 waveguide Teflon-based windows are fabricated and measured. The measured results show a VSWR below 1.15 with an average low insertion loss of 0.08 dB. In addition, the pressure effect on the electrical performance of the pressure window is assessed. A pressure test is carried out, showing that the proposed pressure window designs are suitable for pressures up to 45 and 75 Ib/in 2 without any significant deterioration for WR90 and WR28 waveguide windows, respectively. The proposed pressure windows show superior electrical and mechanical specifications compared with both the state-of-the-art in the literature and the industrial products.

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 antennas are mandatory components in modern communication and radar systems to increase the coverage area. In addition, circularly-polarized antennas have a better penetration capability, which ensures the adequate reception with the presence of obstacles between the transmitter and the receiver. In this article, an X-band high-gain circularly-polarized antenna design is proposed. The introduced antenna has a dual polarization to double the channel capacity through the utilization of polarization diversity. The proposed antenna consists of two horn antennas fed by a magic-tee followed by a ferrite based phase shifter. The presented configuration ensures both, high gain and high power handling capability. The proposed antenna system is centered at 9.5 GHz with a percentage bandwidth beyond 30%.

Circularly-polarized antennas are considered among the most effective antenna types due to their high penetration capability. Further, dual circularly-polarized can double the physical channel capacity over the same frequency through sending different messages over two orthogonal polarization. In this article, a low profile, compact design is proposed for dual-circularly polarized antenna. The proposed structure consists of a hybrid coupler feeding two guided channels, where each channel is loaded with a leaky-wave slot antenna. The entire configuration is designed using Substrate Integrated Waveguide (SIW) technology to provide a low profile and reduce the implementation cost. The proposed design covers a wide band of operation from 27 to 32 GHz, with a matching level below -15 dB. The final structure is simulated with two different numerical packages to provide a sufficient validation for the proposed design.

Passive millimeter components play an important role in all future communication systems. Among the most significant devices are isolators, which are considered as essential protection elements in high power applications. It prevents the RF signal from reflecting to the source, and provide the required protection. It depends mainly on the non-reciprocity to allow the power flow in one direction only. In this work, we have designed an isolator based on the non-reciprocal mode conversion in the mm-wave band. This isolator is realized using rectangular waveguide loaded with horizontal ferrite slab in one path. As a result the wave maintain dominant mode operation in one direction, while the mode is converted to the higher order one on the other direction. Afterwards, the second order mode is collected and terminated to a load to protect the source and realize isolation. The proposed design is modeled and simulated to show the objective performance in the operating bandwidth 27-32 GHz. The proposed waveguide isolator achieved an insertion loss below 0.5 dB with an isolation level above 15 dB over the operating bandwidth.

Gap waveguide is one of the promising technologies in 5G & mm-wave applications due to their low cost, low losses, and high power handling capability. In this work, we have proposed a featured design of an antenna with metamaterial layers to provide a high gain and wide bandwidth simultaneously. The antenna fed by an emerging guiding structure entitled Printed ridge gap waveguide (PRGW), which is planar, lower loss, and works very well at mm-wave frequency range. The antenna offers a stable radiation pattern with a very high gain of 12 dBi, which facilitates the utilization of such an antenna in covering large areas or achieving high penetration.

In this work, a wide band slot antenna with a two-section T-shaped ridge is designed at 30 GHz based on printed ridge gap waveguide technology. Later, to enhance the antenna gain, a multi-layer stepped horn is designed with PCB substrates. The horn results in an overall increase in gain up to 11.5 dBi, and the bandwidth exceeds 26.5% from 26.5-34.6 GHz. The steps walls are realized by metal vias. To control the leakages between the conducting surfaces of the layers, two rows of mushrooms are used around the metal vias to form PEC/PMC parallel-plate waveguides that don't allow for leakage between them. In addition, three rows of mushrooms act as a soft surface around the horn opening to improve the radiation characteristics.

This work introduces a flat coupling backward-wave directional coupler based on a printed ridge gap waveguide (PRGW) technology for mm-wave applications. The construction of the proposed coupler is based on a coupled PRGW lines connected by a central rectangular junction. The coupler is demonstrated to have 8% relative bandwidth at 30 GHz. The prototype of the proposed coupler is fabricated and measured, where the measured and simulated results show good agreement.

Junction circulators are internally matched n-port devices where the input signal to a specific port transfer to the adjacent port and isolated from all other ports. Circulators and isolators are used extensively in many communication systems and defense applications. They are used in splitting the forward and reverse signals in radar applications, which facilitates the signal processing and protects the critical system components such as amplifiers. Most of the current design techniques of circulators presented in the literature have no straightforward procedure and embrace many empirical equations. Such techniques provide approximate and iterative solutions, which increase the time and cost of the development process to achieve the required specifications. In this paper, we present a simple circulators design methodology based on a closed-form solution of the stripline Y-junction including the stripline modes. In addition, we criticize the traditional design methodologies and highlight their limitations and shortcomings. We validate the proposed procedure by two designs for the junction circulators based on the stripline technology. The provided closed-form solution is a revolutionary design methodology as it reduces the lengthy approximate expensive trials to a straightforward and systematic cost-effective technique.

Phase shifters are one of the most important elements deployed in the antenna feeding structures. They are being used in several antenna systems for various applications. Moreover, they can be used in different microwave devices such as circulators and isolators. Furthermore, they are one of the commonly used components in circularly polarized antenna systems. They can be deployed using different techniques depending on the required electrical specifications and the power handling capability. Phase shifters with horizontal ferrite tiles have a higher power handling capability than the transistor based. Thus, this type of phase shifter was frequently visited in the literature. However, the previously presented models were either inaccurate or had a narrow validity range. Here, mathematical analysis and study have been performed for non-reciprocal differential phase shifters using two horizontal ferrite tiles based on waveguide technology. A new model is proposed along with the transcendental equation for the phase constant. The presented model is validated through comparison with various standard waveguides over the full band operation. Moreover, an experimental validation step is carried out, where the measured results have acceptable values.

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.

The near-to-launch 5G standard for wireless communications did not seal the ultimate use the mm-wave bands. As a result, the future 6G standard is expected to proceed in more efficient utilization of these bands. One of the most critical elements in the RF link is the amplifier, especially when the attenuation of the channel is relatively high which is the case for the mm-wave bands. In this work, a reconfigurable design of a wideband amplifier is presented to operate in the band 34 GHz to 38 GHz. The line parameters are investigated to study the tune-ability of this configuration. In particular, changing the parasitic loading by varying lines width can achieve a matching level beyond 15 dB over partial band operations based on the configuration. The availability of such a reconfigurable module will pave the way for efficient 6G development.

The 6G race has already begun, and many countries and giant corporations started directing significant efforts and funds towards the development of the future technology. The 6G standard is expected to migrate to higher bands of frequencies to support wider bandwidth. Through this wide bandwidth, it will be feasible to serve the expected massive number of users and future applications, such as virtual reality and HD realtime transmission. One major problem in high frequency ranges, such as mm-wave bands, is the high signal attenuation, which can be compensated through more efficient amplifier systems. In this paper, we propose a wideband amplifier design fed through a Ridge Gap Waveguide line. The proposed design has many advantages inherited from the host guiding structure. The signal is carried by a Quasi-TEM signal, which minimizes the signal distortion. Also, the structure acts as a large heat sink, which minimizes the operating temperature. As a result, the expected added noise by the proposed amplifier shall be minimal.

Ridge Gap Waveguide (RGW) becomes an important technology to implement passive and active elements for microwave and millimeter bands. One major obstacle in the design procedure is the cell design to achieve the objective operating band. This paper presents a detailed study of RGW, where the design of the unit cell will be turned into a systematic procedure. The presented approach is as an essential complementary step to many articles provided different studies in the same area. The presented study covers RGW structures that operate in X-band, K-Bands and Q-Band. The proposed work will be deployed in the design of the RGW configuration, where both the effort and the time required will be significantly minimized.

Power dividers are critical components for mm-wave applications. They are used in antenna feeding structures to provide the suitable excitation in the antenna array systems and deployed in microwave smart beam switching subsystems. In this article a dual gap wideband in-phase power divider is presented. The bandwidth starts at 19 and ends at 40 GHz. We are targeting with this design both the k and ka bands. The proposed design achieved a very deep matching level below −18 dB.

A nonstandard dual mode, double-ridge waveguide is utilized to design a compact orthomode transducer (OMT). The OMT is terminated with a standard circular waveguide common port and two standard isolated rectangular waveguide ports. The proposed structure exploits a one-fold symmetry to eliminate the coupling to the in-band higher order odd modes within the common port. The proposed concept is utilized to design a full ${K}$ 1-band OMT that is essential for space and mobile applications. Furthermore, the performance of the proposed OMT design is verified through a back-to-back measurement showing an excellent agreement between the full-wave simulations and measurements. Nevertheless, the proposed design achieves a measured matching level of 19 dB for the two modes and isolation level between them beyond 30 dB over the entire band.

A compact asymmetric orthomode transducer (OMT) with high isolation between the vertical and horizontal Ports is developed for the X-band synthetic aperture radar application. The basic idea of the design is to deploy the combined E- and H-plane bends within the common arm. Moreover, an offset between each polarization axis is introduced to enhance the isolation and decrease the size to be around one-third of most of the existing asymmetric OMTs. The OMT achieves better than 22.5-dB matching level and 65-dB isolation level between the two modes. Good agreement is obtained between measurements and full-wave simulations.

Communication systems are witnessing an outstanding revolution that has a clear impact on all aspects of life. The world technology is drifting towards high frequency and data rate solutions to accommodate the future expansion in applications such as 5G communications. The 5G technology will offer advanced features in the mm-Wave frequency band which requires intelligent subsystems such as beam switching. Therefore, the microwave components, especially couplers, still need a significant improvement to follow the rapid variations in future technologies. One of the most recent and promising guiding technologies for mm-Wave applications is the printed ridge gap waveguide (PRGW). In this paper, a design of 3-dB planar quadrature hybrid coupler based on PRGW is presented. The proposed design has superior characteristics such as compactness, low loss, and low dispersion device. The prototype of the proposed coupler is fabricated and tested, where the measured and simulated results show an excellent agreement.

Recently, communication networks are evolving dramatically to meet the human dynamic needs as well as provide the required support for the massive expansion in future applications. This fosters the research in the mm-wave components to create a new infrastructure for these applications. As a result, the electrical characteristics of the designed components in terms of the bandwidth and the linearity have to be evaluated in an accurate way. The linearity of the mm-wave components is evaluated through the assessment of the inter-modulation of these components, especially at the second harmonic band. In this paper, a -17-dB harmonic coupler is designed to pick a strong sample at the second harmonic, while suppressing the fundamental signal at the coupled port. A design procedure for the proposed harmonic coupler is presented and illustrated. The fabricated unit is silver plated to minimize the losses, where the measured coupling at the second harmonic band shows an excellent agreement with the simulated ones. In addition, the measured coupling level at the fundamental band is below -75 dB.

Hybrid couplers are essential devices in various microwave circuits and systems, such as radar systems and beam forming networks. The development of this device is necessary along with the development of the new communication standards for the most modern guiding structures. One of the most recent and promising guiding technologies is the ridge gap waveguides, which is expected to play an essential role in the millimeter wave and submillimeter wave applications, not only the 5G communications but also other future communication. Therefore, standards are recommended to make use of the high-frequency guiding structures. In this paper, a design procedure for the hybrid couplers is presented. The frequency band of interest is centered at the 15 GHz, which can be deployed for both the 5G mobile communication and the airborne radar applications. The proposed design is fabricated and measured. The measured and simulated results are in excellent agreement.

Lately, there has been a growing interest in the ridge gap waveguide (RGW) technology as a guiding structure for high-frequency applications. Low loss and low dispersion are two major advantages of the RGW. On the other hand, the major disadvantage of this technology is the difficulty in fabrication as it requires fabrication with high precision, in particular for high-frequency applications. The operating bandwidth of the RGW is controlled by the stopband of the texture surrounding the ridge. A study to enhance the bandwidth is introduced for possible utilization of the full band achievable by the unit cell in the presence of the ridge. Modifications of the cell filling shape and the ridge structure are carried out to enhance the RGW bandwidth. We have introduced a new RGW based on mixed fabrication technology. The proposed architecture introduces adaptive and straightforward structure with improved bandwidth while keeping the characteristic impedance at the same value. The proposed structure is fabricated and measured. The measured scattering parameters are in excellent agreement with the simulated ones.

It is useful to determine the stopband of a bed of nails that can be used for packaging applications. The traditional methodology to identify the cell characteristics is to use the eigenmode solver, which is a numerical method that cannot be validated using a measurement setup. Here, we introduce a mathematical procedure to extract the dispersion relation out of the scattering parameters. The scattering parameters express the transmission and the reflection at the ports, which are functions of the phase constant of the propagating modes inside the device under test. A measurement setup is established by placing several successive cell rows inside a $Ku$ -band rectangular waveguide. The proposed algorithm is validated through examples of well-known dispersion relations. The extracted dispersion relation with the introduced methodology is in good agreement with the one obtained from the eigenmode solver. The ride gap waveguide is used as an application example.

In this letter, a precise model for accommodating the cross-guide couplers is proposed and validated. This includes accurate formulas for the polarizabilities of cross slots as well as the effect of finite wall thickness on the coupling level. The proposed model shows a leading performance compared with previously published models in the literature showing a maximum error of 2.5%. The experimental validation shows an excellent agreement with the simulated results.

Recently, ridge gap waveguides are considered as guiding structures in high-frequency applications. One of the major problems facing this guiding structure is the limited ability of using all the possible bandwidths due to the limited bandwidth of the transition to the coaxial lines. Here, a review of the different excitation techniques associated with this guiding structure is presented. Next, some modifications are proposed to improve its response in order to cover the possible actual bandwidth. The major aim of this paper is to introduce a wideband coaxial to ridge gap waveguide transition based on five sections of matching networks. The introduced transition shows excellent return loss, which is better than 15 dB over the actual possible bandwidth for double transitions.