A low‐cost broadband millimeter‐wave bias tee network using SICL technology

Abstract

This article presents a substrate integrated coaxial line (SICL)‐based low‐cost bias tee network operating in K‐ and Ka‐band (20–29 GHz). A butterfly stub is introduced in the direct current (DC) circuit path for the radiofrequency (RF) isolation. A single‐layer ceramic capacitor is used along the RF mainline to provide the DC isolation. The size of the proposed circuit is , where is the guided wavelength at the center frequency of 24.5 GHz. The proposed design exhibits 0.5–1 dB insertion loss in 20–25 GHz and 1–2 dB insertion loss in 25–29 GHz, along with more than 30 dB isolation between RF and DC circuits with good impedance matching. The isolation is improved by adding a series of butterfly stubs. Moreover, a design method for realizing a mounting pad to connect the surface‐mount device (SMD) capacitor with the SICL line is proposed. The proposed method helps integrate SMD component in the SICL environment. The parasitic effects of the pad are analyzed with the help of an equivalent circuit. This circuit is most suitable for 5G FR2 (millimeter‐wave) band application.