High Efficiency Waveguide-Planar Amplifier with Spatial Power Combining for Frequency Range 31–39 GHz

Abstract

The article presents the development results of the hybrid-integrated waveguide-planar amplifier circuit for 8-mm wave range with spatial power combining. Affordable and inexpensive low-noise UMS CHA2494-QEC integrated amplifiers are used in the developed circuit. To improve the efficiency of power combining, new longitudinal probe transition designs from a rectangular waveguide to a coplanar strip line (CSL), and to a microstrip line (MSL), whose dimensions do not exceed 0.4λ₀, are proposed. As a result of the amplifier electromagnetic system development, a high efficiency of power combining has been achieved up to η ≈ 85%. The paper presents the experimental results of phase-shift keyed signals transmission through the developed amplifier with a signal level that is slightly lower than the level of 1 dB gain compression. On the basis of the proposed model, the amplifier degradation was also theoretically investigated for various failure modes of one of its active elements.