Robust design of a broadband dual-polarized transition from PCB to circular dielectric waveguide for mm-wave applications

Abstract

A growing interest in dielectric waveguides (DWGs) as an alternative to commonly used waveguides (like coaxial or twisted-pair cables) for high data rate interconnects could be observed in the last few years. Especially in the mm-wave frequency range (30–300 GHz) applications with these waveguides benefit from low losses and low dispersion. Moreover, using both polarizations of the fundamental mode in such waveguides could theoretically double the data rate without the need of higher bandwidth or additional fibers. The connection between DWGs and commonly available transceiver chips requires broadband transitions from planar waveguides like microstrip lines to DWGs. In this paper, an overview of the current developments of such transitions is given and a novel low-complexity design is presented that reduces the space consumption by 35% related to recently published works. This allows an easy integration into a printed circuit board layout or a chip package. Furthermore, an extensive sensitivity analysis is presented to prove the robustness toward manufacturing tolerances. The transition is realized at W-band frequencies (75–110 GHz) and achieves a relative 10 dB-bandwidth of more than 25% with a minimum insertion loss of 1.2 dB. It is shown that these properties even hold for manufacturing tolerances of nowadays manufacturing processes.

Signal distortions in circular dielectric waveguides at mm-wave frequencies

“…For this reason, higher values of R 1 (V ≈ 2-3) in combination with low-loss core materials are preferred in mm-wave applications. From (10) and (14), the Taylor coefficient α 0 at a certain fre-…”

“…The use of low-loss materials or different designs (e.g. hollow core fibers) for DWGs [7][8][9] as well as the enhanced coupling into DWGs [10][11][12][13][14] ensure a low insertion loss of the transmission channel and therefore increase the SNR at the receiver. In addition to signal distortions caused by noise, a broadband signal transmitted along a DWG is also disturbed by the frequencydependent propagation characteristics of the DWG channel.…”