Abstract: An external antenna adapted to a communication host and a wireless communication system are provided. The wireless communication system includes the external antenna and the communication host. The external antenna includes a first antenna element, a second antenna element, a logic determination circuit and a switching circuit. The first antenna element is configured to receive a wireless signal when the communication host operates in a reception mode. The second antenna element is configured to transmit the wireless signal when the communication host operates in a transmission mode. The logic determination circuit coupled to the communication host is configured to determine whether the communication host operates in the reception mode or the transmission mode so as to generate a determination result. The switching circuit, coupled to the logic determination circuit, is configured to selectively couple to the first antenna element or the second antenna element based on the determination result.