An approach to the ideal circuit for power combining

Common circuits for power combining are discussed and compared to an ideal structure, which can be approached by utilizing evanescent mode resonators. A medium Q and a low Q oscillator are described with up to eight IMPATT diodes working in X-band. Circuit efficiency exceeds 90%, with a mechanical tuning range of 500 MHz and 1.5 GHz, respectively. Locking bandwidth amounts to 160 MHz and 450 MHz, respectively. These data prove that a lumped element structure can be realized, which behaves like a single resonant circuit over a wide frequency range.