Abstract: A matching circuit for a screen antenna receives on its signal input an MF or LF signal output of a screen antenna and feeds a signal though its signal output via a capacitive feeder to a radio receiver. The matching circuit includes components which operate in conjunction with capacitances in components connected to the signal input and the signal output to form an internally-terminated band-pass filter network having a pass-band which covers a range of frequencies to be received by the receiver.

Abstract: There is disclosed an antenna arrangement for a vehicle window, particularly suitable for reception of signals in the UHF band while minimising the effect of fast fading. The antenna comprises antenna elements which generate at least two orthogonal or largely orthogonal modes. In reception, one or other mode may be selected such that the antenna effectively operates as a diversity antenna. Alternatively, the two modes may be combined to tailor the polarisation and directional properties of the antenna. For transmission, the properties of the antenna can be tailored to interact favourably with a particular vehicle to which it is applied. These properties may be controlled by a suitable combining circuit.

Abstract: A bifilar coil construction is used for isolating radio signals picked up by a motor vehicle window heating element from the power supply circuit for the heating element. The coil construction has two separate windings (9,10) which are arranged bodily alongside each other. In one embodiment there is an inner cylindrical winding (9) within and in contact with an outer cylindrical winding (10), and a two part pot core (15,16) is clamped within and around the windings (9,10).

Abstract: A device for use with an electrically heated window to enable it to be used as a radio antenna has a bifilar wound choke (2) which allows passage of heater current while isolating radio signals from the heater power circuit. The device is connected to radio apparatus via an amplifier (13). The choke (2) and the input of the amplifier (13) are both of relatively low impedance. The choke (2) may be a pot-cored bifilar winding and the amplifier (13) may use a field effect transistor in its input stage connected in grounded gate configuration.

Abstract: A bifilar coil construction is used for isolating radio signals picked up by a motor vehicle window heating element from the power supply circuit for the heating element. The coil construction has two separate windings (9,10) which are arranged bodily alongside each other. In one embodiment there is an inner cylindrical winding (9) within and in contact with an outer cylindrical winding (10), and a two part pot core (15,16) is clamped within and around the windings (9,10).