| 摘要 |
An electronic antenna switching system switches between an internal and an external antenna (105, 107) on a portable radiotelephone (103). Here, the external antenna (107) contains a coil cord connector (111). In the coil cord connector (111) an electrical ground or a predetermined voltage is applied to a center conductor (205) of a coax cable (201). Internal to the radiotelephone (103), an antenna detector circuit (113) detects when the second antenna (107) is attached to the electronic antenna switching system and generates a control signal (119) in response thereto. A switch (115) switches the active transmission path between the internal and the external antenna's transmission path in response to the control signal (119). |
