Unloaded Quality Factor for Hairpin Resonator Affected by Conduction and Radiation Losses on K-band

Abstract

We investigate the effects of an Electroless Nickel Immersion Gold (ENIG) layer, the roughness of mat face on copper foil, and the radiation loss along a microstrip line and input/output coaxial connectors. The surface finishing process for planar circuits using a printed circuit board (PCB) is very important for preventing the corrosion of copper foil. There is a problem with coating the surface of copper foil because the conduction losses caused by the materials for surface finishing are higher than that of low-frequency bands. In addition, the roughness of the mat face on copper foil strongly affects the losses of the circuits at high frequencies. Moreover, radiation losses by coaxial connectors or some bonding methods like wire-bonding are a problem. In this paper, we distinguish some causes of losses in a hairpin resonator and a two-pole band-pass filter (BPF) by developing some theoretical equations and electromagnetic simulation models. Also, this verification is applied to the measured results of two-pole BPF. The effects of ENIG, copper roughness and radiation between coaxial connectors and a microstrip line on unloaded quality factor (Q 0 ) of the hairpin resonator are quantitatively revealed.