Design and experimental verification of ridge gap waveguide in bed of nails for parallel-plate mode suppression
P.-S. Kildal, A.U. Zaman, E. Rajo-Iglesias, E. Alfonso, A. Valero-Nogueira
IET Microwaves, Antennas & Propagation
Volume: 5, Issue: 3, Feb. 2011
262 - 270
This study describes the design and experimental verification of the ridge gap waveguide, appearing in the gap between parallel metal plates. One of the plates has a texture in the form of a wave-guiding metal ridge surrounded by metal posts. The latter posts, referred to as a pin surface or bed of nails, are designed to give a stopband for the normal parallel-plate modes between 10 and 23 GHz. The hardware demonstrator includes two 908 bends and two capacitive coupled coaxial transitions enabling measurements with a vector network analyser (VNA). The measured results verify the large bandwidth and low losses of the quasitransverse electromagnetic (TEM) mode propagating along the guiding ridge, and that 908 bends can be designed in the same way as for microstrip lines. The demonstrator is designed for use around 15 GHz. Still, the ridge gap waveguide is more advantageous for frequencies above 30 GHz, because it can be realised entirely from metal using milling or moulding, and there are no requirements for conducting joints between the two plates that otherwise is a problemwhen realising conventional hollowwaveguides.
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