In this paper, an antenna is presented for in-band full duplex technology. This antenna includes a microstrip patch and a new 180 hybrid coupler. The designed 180 hybrid coupler has new structure that miniaturizes the entire system and also eliminates the self-interference signal that leaks from transmitter to receiver. In this antenna, at 2.4 GHz, an isolation between transmit and receive ports is more than 79 dB. Additionally, in this antenna, the measured inter-port isolation is better than 68, 72, and 74 dB for 80, 50, and 20 MHz bandwidths respectively in 10 dB return loss impedance. The dimensions of the designed antenna are 68 mm  60 mm, and in compare with similar designed antenna is considerably smaller (more than 60%) with acceptable isolation.