A Compact and Broadband Directional Coupler for High-Power Radio Frequency Applications

In this letter, a compact and broadband directional coupler is proposed for high-power radio frequency applications in the frequency band of 5–150 MHz. The coupler is composed of a suspended semiflexible coaxial cable and a series of equalizers composed of lumped components. Such design exhibits excellent performance in high power handling capacity (~kW), high directivity (~35 dB), low return loss (>20 dB), and flat coupling coefficient (45 ± 1.3 dB).