Planar groove gap waveguides

With the increasing demand for wireless services and applications, the integration and coexistence of multi-standard and multi-band operations into a single device has led to intensive research in the design of tunable and reconfigurable planar devices. A planar medium to achieve this integration is the Substrate Integrated Waveguide (SIW). However, due to a lack of DC isolated planes of the structure, bridging wires or concentric etched rings are often used to enable active device biasing. This research presents a novel planar structure referred to as the Planar Groove Gap Waveguide (PGGWG). The new structure has similar modal characteristics to air-filled machined Groove Gap Waveguide (GGWG), but in a low-cost fabrication technology that is readily integrated with surface mount components. The structure provides two DC isolated conducting planes, while still providing a low loss planar transmission medium. Simulation results demonstrate the existence of a TE10 propagating mode within the artificially created bandgap. There is good agreement between de-embedded simulated and measured results over the usable bandwidth of the waveguide (28 to 40 GHz). A passband is measured having an average insertion loss of 1.2 dB and 0.5 dB insertion loss variation implemented on a substrate of relative permittivity r of 3.5, and loss tangent of 0.004. The broadband characterization of the transmission line loss and phase constant for PGGWG at Ka-band shows that PGGWG has comparable attenuation over the band of interest to SIW. The transmission line Q-factor is found to vary from 135 to 140 over the band of interest, which is comparable to SIW in the same medium. PGGWG is also found to have a phase constant of nearly double that of comparable SIW, which is a significant results for system miniaturization. The unloaded Q-factor of a 33.5GHz PGGWG rectangular cavity resonator is measured to be 209. This is found to be comparable to an SIW resonator on the same substrate and frequency band. This work further explores the DC isolation property of the PGGWG by presenting electrically tunable PGGWG resonant cavities. It is found that a simple biasing network can be applied to the cavity using a varactor diode to vary the resonant frequency of the cavity. This is done without bridging wire and concentric etched rings as a direct result of the DC isolation of the PGGWG. A tuning range of 4.5% is achieved in measurement. From the experiments conducted, it is concluded that PGGWG can be used as an alternative planar waveguide media. The PGGWG platform can be used in the design and implementation of RF front-end components at millimeter waves. Its DC isolated conducting planes also provide a simple way of biasing active components in frequency agile applications.

Grantor

Department of Electrical Engineering

Year dc:date.issued

2019

Author dc:creator

• Oyedokun, Titus Oluwale

Advisors dc:contributor.advisor

• Geschke, Riana
• Stander, Tinus

Handle dc:identifier.uri

http://hdl.handle.net/11427/30173

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/30173