A Waveguide Mode-Converter Feed for a 5-W, 34-GHz Grid Amplifier

Abstract

We have demonstrated a compact waveguide mode converter that excites a combination of TE_(10) and TE_(30) modes for feeding a grid amplifier. The length of the mode converter is only 13mm. The effective transmitter power (ETP) at 34GHz is 5W, with a gain of 5.5dB and a power-added efficiency (PAE) of 21%. The supply voltage is 3V, with a bias current of 5.6A. These results are comparable to those reported earlier for the same grid-amplifier design measured in free space. A spurious oscillation with a broad radiation pattern was observed at 33.6GHz with an effective isotropic radiated power (EIRP) of 23mW. This oscillation was suppressed when the grid was operating at high power levels, and disappeared entirely at output powers above 4.5W.

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