This paper presents a stacked patch antenna array that operates at a 5.8 GHz of ISM band for microwave power transmission (MPT) applications. The stacked patch antenna consists of three layers that include a circular patch antenna with an air-gap, a stacked parasitic patch, and a feed-network. Each patch has a crossed-slot to form the right-handed circular polarization. A $2\times 2$ element array has been made up of the stacked patch antennas connected with a sequentially rotated feed-network. The measured axial ratio and gain of a $2 \times 2$ array are 1.08 dB and 11.6 dBic at 5.8 GHz. The feed network has been printed on a substrate with a relatively high thermal-conductivity to withstand high-power. The thermal analysis of the feed network is compared with cases of substrates.
