Abstract

The usage of high frequency microwave devices is rapidly increasing with the advances achieved in the communication systems. However, the standard guiding structures have high losses such as microstrip technology, or difficulty in manufacturing such as in the case of waveguides. The newly developed ridge gap waveguide (RGW) technology resolves the problems above as it has low losses and does not require electrical contacts as required in the waveguides. The concept of RGW is simple as it allows the wave propagations in the guiding part and eliminates the leakage in all other directions. The region that surrounds the ridge consists of two parallel surfaces; one is a perfect electric conductor (PEC) and the second is a perfect magnetic conductor (PMC). The gap between the two surfaces should be less than a quarter wavelength. Periodic conducting nails realize the PMC that practically has a possible bandwidth 2.5:1 and in some cases exceeds 3:1. Usually, the design of these surfaces relies on the unit cell analysis that is based on determining its band gap, the estimation of the band gap is performed numerically. The band gap of the cell is the operating bandwidth of the complete structure. For the first time, we presented a method to measure the band gap from s-parameter measurements. Utilization of the broadband characteristics strongly depends on the proper design of the transition between the RGW and the standard guiding structures and connectors. Most of the available transitions make use of around one-third of the possible bandwidth. Therefore, we present new transitions that utilize the whole possible bandwidth of the RGW. The presented work can be divided into four major parts. Several microwave components are designed based on the RGW such as power divider, hybrid couplers, and a circulator. New methods are presented for efficient and accurate design of these components. One of the main contributions is related to the RGW circulator design; it's an accurate design procedure that can be used with other technologies as well. In addition, a new setup to measure the low relative permittivity of thin materials such as fabrics is presented. An example of a leaky wave antenna using split slot arrays is presented. These studies highlight the RGW advantages and can be considered as a step towards the standardization of this technology.