A broadband directional coupler based on ferrite cores

Abstract A broadband directional coupler based on ferrite cores is proposed for high frequency (HF)/Very high frequency (VHF)/Ultra High Frequency (UHF) communication systems. The transformer‐type coupler is composed of two double‐aperture ferrite cores and 1‐mm‐diameter strands. The ferrite cores with different relative permeabilities are screened to achieve an ultra‐wide bandwidth (5 –1000 MHz). The coupler demonstrates excellent electric performances. The voltage standing wave ratio of each port is less than 1.2, a stable −20 dB coupling level is maintained over the operating bandwidth and the insertion loss is less than 0.8 dB. Such couplers have compact sizes and are of very low cost