Millimeter-wave Solid-state Power Combining Technology Research

Millimeter-wave power source is the key component of millimeter-wave transmitter system in millimeter-wave system. With the frequency increasing, the output power of a single solid-state device would be decreased rapidly. Especially at millimeter-wave frequencies, the available output power from each monolithic device can't meet the challenge of the engineering system. So it comes to be the key of millimeter-wave system developing that obtaining the advantages of the devices' small size, lightweight, high reliability etc in millimeter-wave system by increasing the devices' output power. By combining some coherent devices or superposing discrete devices' output power we can enhance the available output power obviously.By means of researching various combining methods in domestic and overseas, and taking the domestic technology conditions account, this paper designed a wide band power dividing/combining network, and assembled a solid-state power amplifier in frequency range 32 to 38 GHz, which aimed at the problem about limited room and elimination of heat in millimeter-wave spatial power combining waveguide based. The measurement result indicates that the amplifier' average combining efficiency in the frequency range 30 to 40 GHz is up to 85%, and max combining efficiency is up to 90%. It has ideal effect.We emphasis on solving the key problems about the low-loss waveguide dividing structure, waveguide to micro-strip transition, elimination of heat in limited room in combining efficiency's enhancement in the process of designing the combining networks. This paper analyzed the problems' influence on power combining by simulation and calculation, and separately used the methods of waveguide directional coupler, double probe transition in H plane, elimination of heat by top-bottom metal cavity to solve them.According to the exploratory of this paper's structure, we adopt low-power amplifier. Its max output power is up to 23.5dBm, and the cost is low. We have obtained the result that the max output power is 28.5dBm by combining quadruple using the structure. It proved the structure's feasibility and well prepared for the later work operating more devices and higher power.