Shoukry I. Shams

Double cone ultra wide band unit cell in ridge gap waveguides

Ridge gap waveguides are proposed for high frequency applications. The propagating mode inside these structures is the Quasi TEM mode, where the signal is propagating between two parallel electric conducting surfaces and attenuated off its intended path by replacing the off path surface by an artificial magnetic conductor (AMC). The operating bandwidth of the ridge gap waveguides is a function of the stop band of the unit cells that form the AMC. The bandwidth of the basic shapes of the Bed of Nail Unit Cells (BNUC) is about 2:1 and some trials were presented to propose different shapes of bandwidth about 3:1. This work introduces a different nail shape that provides a bandwidth ratio of almost 5:1. Parametric investigations are presented to clarify the critical parameters that affect the bandwidth as well as a study of complete design using the proposed cell structure.

Wideband Coaxial to Ridge Gap Waveguide Transition

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.

Broadside uniform leaky-wave slot array fed by ridge gap splitted line

Recently, Ridge Gap Waveguides (RGW) become one of the most promising waveguide technologies. This type of guiding structures carries the signal in the form of Quasi TEM wave inside an air gap. This leads to less dispersion in the propagating signal and uniform field distribution across the guide. Here, a design of a magic tee feeding a splitted ridge gap line is presented. This ridge gap splitted line is exciting a broadside uniform slot array. The design of the magic tee with the splitted line ensures the elimination of the grating lobes. Step by step design is presented as well as the final radiation patterns of the whole slot array.

Relative permittivity extraction of Textile materials based on ridge gap waveguide technology

The Textile materials are widely used recently in microwave applications. The wearable antennas and the medical applications generate high potential to explore the electrical characteristics of the Textile materials. The mechanical properties of such materials are well known but the challenge is to determine the electric characteristics in an accurate way specially the relative permittivity. There are many traditional methods to identify the relative permittivity of an unknown material e.g. Coaxial probe method, the waveguide method, the free space method, and the cavity method. On the other hand, the Textile materials have relatively small standard thickness. This put some limitations on the used measurement technique. The objective is to select a suitable measurement technique for wide band operation and a small thickness for the sample under test.

Ridge gap waveguide to microstrip line transition with perforated substrate

Summary form only given. The ridge gap waveguides is one of the highly recommended guided structures in high frequency applications. This is due to its ability to carry the signal with low losses. The signal pass through this structure in the form of Quasi TEM mode, which grantee less dispersion compared to other structures working in the same operating band with ridge gap waveguide, like SIW. One of the major drawbacks of the ridge gap waveguide is related to the used excitation technique. It is always difficult in fabrication and in many cases, it is responsible for limiting the possible bandwidth of the structure. One simple and straightforward idea is to connect the ridge gap waveguide to one of the standard 50Ω lines, such as Microstriop lines or Coplaner waveguides. This work is focused on the Microstrip line case. It is required that the ridge waveguide is directly connected with the 50Ω Microstrip line. The direct connection will have a certain level of mismatch and the reflection increases as the dielectric constant of the microstrip line substrate increases. As a first step of the transition design, a low relative permitivity substrate is chosen. This initially reduces the reflection occurs at the transition. The second step of the transition design is to insert two sections of matching between the microstrip line and the ridge gap waveguide with the help of lower dielectric constants substrates than those used in the microstrip line. The substrates with these lower dielectric constants can be achieved by using the same substrate and apply perforation. Controlling the perforation density will adjust the relative permitivity of the substrate at the required value to achieve matching. Using the previously described technique, the ridge gap waveguide can be attached directly to a 50Ω microstrip line. Connecting the microsrtip line to one of the standard coaxial connectors, like (SMA, 2.4mm, 3.5mm or 1.85mm), is a well-established connection. This provides a very easy procedure for ridge gap waveguide measurements. It is worth to mention that the fabrication process for such a transition is very simple as it is a two dimensions printed structure. To eliminate the radiation of this transition, an extension of the periodic cells is placed in the microstrip line side. Within the microstrip line part, the periodic cells will introduce some sort of packaging to get rid of leakage due to radiation. This extension also provides more smooth transition between the ridge gap waveguide and the microstrip line packaged with similar periodic structure. One important point that should be taken into consideration is that the substrate thickness of the microstrip line must be exactly the same as the gap height in the ridge gap structure.

Design of 3-dB Hybrid Coupler Based on RGW Technology

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.

Wide band power divider based on Ridge gap waveguide

The Ridge gap waveguide is a promising guiding structure, where there is no need to ensure the electrical contact and it has a possible operating bandwidth of 2:1 or even more. However, most of the presented passive devices based on this technology support a small portion of the possible bandwidth. This limitation is due to either the objective device or the excitation technique. In this work, a wide band power divider is introduced. The bandwidth of the presented power divider is from 10.3 GHz to 20.3 GHz, which is, almost, the possible bandwidth of the Ridge Gap Waveguide (RGW) unit cell. The matching level of the complete structure is better than 17 dB for the operating bandwidth.

90° phase shifter based on substrate integrated waveguide technology for Ku-band applications

Wireless systems are in a growing need for compact size phased antenna arrays, hence, compact phase shifters, as well. 1n addition, there are other numerous applications like isolators, filters, and couplers that deploy the phase shifter as an essential component. To implement the phase shifter in a compact size, the Substrate 1ntegrated Waveguide (SIW) structure is selected. SIW technology has almost all the properties of rectangular waveguides. However, it keeps the advantage of the compactness and integration capability. The mode supported by SIW structures is the TE 10. This work introduces ferrite phase shifter with compact size compared to the traditional ferrite phase shifters that are bulky. The proposed non-reciprocal 90° phase shifter is based on SIW technology with less than ±15° of phase variations over the Ku-band.

Printed Texture With Triangle Flat Pins for Bandwidth Enhancement of the Ridge Gap Waveguide

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.

Determining the Stopband of a Periodic Bed of Nails From the Dispersion Relation Measurements Prediction

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