Abstract: With the rapid development of LEO broadband communication satellite constellations，a Kaband slot coupled dualpolarization transmit phased array antenna is proposed to meet the requirements of fast crossbeam switching and low profile for satellite communication. The antenna layer, power supply and control layer, power distribution network layer and chip layer are integrated together. The duallinearly polarized antenna and phase shifter are adopted to achieve circular polarization switching and polarization switching. The subarray rotation arrangement is also used to realize the second circular polarization. The integrated, lowprofile phased array is fabricated and tested. The results indicate that the phased array is operated at 27.5~31GHz，achieving ±60° scanning, circular polarization switching, and EIRP 16.5dBW@29.2GHz. The thickness of phased array is about 3mm. Compared with the traditional brick phased array antenna, the profile and weight are greatly reduced, which is of great significance to the general utilization of phased array antennas for satellite communication.