Abstract: A control unit is inserted in the power lines that serve a vehicular telephone and an audio system. A power monitoring circuit detects current increases related to operation of the telephone, either from an incoming "ring" signal or the "off hook" condition in preparation for an outgoing call. The monitoring circuit generates a control signal which is applied to an electronic switching circuit that interrupts the flow of power to the audio system circuits. So long as the telephone is in use, the audio system is disabled. When the telephone returns to the quiescent or stand-by state, the current drawn by the telephone drops substantially below a threshold level of the monitoring circuit and the switching circuit restores the power to the audio system.

Abstract: A mobile transmitting and receiving communications antenna assembly for use on a vehicle, includes a primary radiating element a secondary radiating element having first and second radiating elements, normal to a longitudinal axis of the primary radiating element to form a ground plane therefor. Impedance matching means, comprising a tuned circuit tuned to the nominal resonant frequency of the capacitively loaded antenna and electrically connected to the second electrically conductive coupling member in the immediate proximity thereof to resonate in conjunction with said primary radiating element. The impedance matching means displaying an impedance which varies between a first impedance at the connection to the second electrically conductive coupling member which is substantially equal to the impedance at the base end of the primary radiating element and a second impedance at least several orders of magnitude less than the first impedance.