Diode mounting topologies for X-band waveguide switches

A waveguide PIN diode mount with thermal model for high-power applications

“…POWER CHARACTERISTICS An X-band switch consisting of three cascaded diode sections, as shown in Fig. 4, was used to further refine and verify the proposed thermal model [3]. An AWR Microwave Office analysis of the equivalent circuit is used to determine the current through each set of diodes.…”

“…Two PIN diodes are soldered onto the top and the bottom of the central-ground plate, respectively. [3] Feed lines, constructed from 0.1 mm copper shimstock with added circular pads at the ends, feed DC bias to the top and bottom diodes. The circular pads serve as one side of tunable air-gap capacitances, formed between the pads and tuning rotors entering from the top and bottom of the waveguide.…”

“…This makes the calculation of the maximum power handling capability extremely difficult. To enable such a prediction, this paper presents a procedure for the creation of an extended full thermal model for application to both CW and pulsed applications, for a specific PIN-diode mounted in the structure in [3]. The model takes into account the packaged diode as well as the mounting structure, and is tested for both CW signals and pulsed signals down to 24 μs for power levels of up to 4 kW.…”

“…al. [3] proposed a novel waveguide PIN-diode mounting structure which makes use of evanescent-mode waveguide, and allows for high-power handling capabilities as well as the ability to tune the resonance frequency of the whole structure after manufacturing and assembly. An outline of the structure is shown in Fig.…”