Design, manufacture and test techniques for multipactor free RF devices

Summary form only given. Sierra Microwave has been involved in the design, manufacturing and testing for multipaction of numerous high power RF passive devices, including isolators, circulators, filters, power divides/combiners, loads, etc for use in space environment. During the design phase, the device is usually analyzed using E-M simulation resulting in the electric field distribution, gap voltage values and multipaction threshold for the critical regions of the structure and optimized to reduce the gap-voltages and increase multipaction threshold. For ferrite devices operating under DC magnetic field, multipaction analysis includes both electric and magnetic fields to account for electron confinement. Coaxial and Waveguide interfaces are common with TNC and TNC Wedge being the most common from VHF through C band. Typically, C band and lower frequency high power devices require some degree of design mitigation to comply with the system multipaction margin requirements. Some of these common methods will be discussed. In this work, examples of some high power RF devices that were designed and successfully tested for multipaction at Sierra Microwave will be presented, including a WR112 waveguide circulator in X-band tested to 3000 Watts peak (600 Watts average), a VHF lumped element band pass filter tested to 80 Watts peak (4 Watts average) and an L-band coaxial isolator-combiner tested to a combined output power of greater than 1900 Watts peak (755 Watts average). The design approach, multipaction mitigation methods, test methods and test results for each of these parts will be presented and discussed.