A compact, broadband three-way substrate integrated waveguide power divider with improved isolation

Abstract

Purpose This paper aims to present a compact, broadband substrate integrated waveguide (SIW) three-way power divider with improved isolation based on six-port SIW coupler. Design/methodology/approach The power coupling among the three output ports occurs due to short openings in the narrow walls of the central SIW channel. Performance improvement in the isolation and return loss among ports is achieved using matching posts placed at the input and output ends of the coupling region. This enhances the coupling between TE10 and TE30 modes. The input matching ports enhance the return loss, whereas the isolation is alleviated by both the input and output matching posts. The bandwidth enhancement is achieved by optimizing the outer SIW channel widths. Findings The measured fractional bandwidth of 27.3% with over 15 dB of isolation and return loss is achieved. The coupling length is 1.55 λg at the centre frequency. The power divider achieves better than 15 dB isolation between non-adjacent output ports. The measured reflection and isolation coefficients are in close agreement with simulated results over 8.2 to 10.8 GHz. Practical implications Isolation between the adjacent and non-adjacent ports is an important parameter as the reflections from these ports will interfere with signals from other ports reducing the fractional bandwidth of the power divider and affecting the overall performance of the transmitters and receivers. Originality/value The authors present the enhancement of isolation between the output non-adjacent ports by optimizing the SIW channel width and matching post in the coupling region to reduce the reflected signals from non-adjacent ports entering into other ports. To the author’s knowledge, this is the only SIW three-way power divider paper showing non-adjacent port isolation among six-port couplers based three-way power dividers.