A Compact Broadband Transparent Waveguide Window Based on Low-Loss Cyclic Olefin Copolymer

The concept of compact waveguide window based on the low-loss cyclic olefin copolymer (COC) is proposed in this letter, which considers the characteristics of broadband performance, transparency, sufficient mechanical strength, and simple mechanical process, by simply integrating the machined bipyramids-type COC dielectrics into the modified waveguide. To verify our idea, two waveguide windows consisting of internal dielectrics and external fixtures are designed and fabricated. The two types of waveguide windows are measured along with two strain rectangular waveguides at the Ka-band with the return loss better than 18.5 dB over the related frequency range of 42.8% and better than 20 dB over the related frequency range of 49%, respectively. The measured results show the advantages of the proposed concept, which is an excellent candidate for broadband application at a millimeter-wave frequency or higher.