New Directional Couplers for Multimode Circujlar Waveguides Applied to Intense Pulsed Microwave Systems

Three new types of directional couplers are described for use in overmoded circular waveguide operating in the TM0 1 mode. The types are (1) circular/rectangular waveguide multihole couplers, (2) circular waveguide/coaxial multihole couplers, and (3) circular waveguide loop couplers. These directional couplers are designed to diagnose intense pulsed microwave systems in the frequency range 3 - 18 GHz. Coupling coefficients vary between 50 dB and 70 dB with directivities between 13 dB and 20 dB. These devices have been used to measure the output powers of relativistic magnetrons and backward wave oscillators (BWOs) in the power range 100 MW to 300 MW.