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: 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: The present invention relates to an antenna for use on a motor vehicle, particularly for cellular radio communication. The antenna comprises an elongate conductor applied to the surface of a vehicle window, the length of the antenna elongate conductor being a minor portion of the length of any peripheral side or edge of the vehicle window. A ground plane is provided along the top edge of the vehicle window, and the top end of the conductor antenna is grounded by virtue of its close proximity to the ground plane.

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: The present invention provides within three particular aspects thereof an isolating and matching device operable to enable an electrically heatable window of a motor vehicle to be used as an efficient VHF communications aerial or antenna; wherein isolating and matching circuitry is provided for Series VHF Matching, Shunt VHF Matching and Split Passband Matching of an electrically heatable window heating element to an aerial input impedance of an aerial feeder circuit of a radio frequency receiver or transmit/receive device.

Abstract: The present invention provides within three particular aspects thereof an isolating and matching device operable to enable an electrically heatable window of a motor vehicle to be used as an efficient VHF communications aerial or antenna; wherein isolating and matching circuitry is provided for Series VHF Matching, Shunt VHF Matching and Split Passband Matching of an electrically heatable window heating element to an aerial input impedance of an aerial feeder circuit of a radio frequency receiver or transmit/receive device.

Abstract: The present invention provides within three particular aspects thereof an isolating and matching device operable to enable an electrically heatable window of a motor vehicle to be used as an efficient VHF communications aerial or antenna; wherein isolating and matching circuitry is provided for Series VHF Matching, Shunt VHF Matching and Split Passband Matching of an electrically heatable window heating element to an aerial input impedance of an aerial feeder circuit of a radio frequency receiver or transmit/receive device.

Abstract: The present invention provides diversity reception to effectively compensate for signal reception fading without using separate antenna structures and while using the heating element antenna of an electrically heated window of a motor vehicle. Such is accomplished by providing common (unbalanced) and balanced signal separation configurations and signal selection circuitry between the heating element antenna and the VHF aerial input terminal of a vehicle radio receiver, wherein the signal selection circuitry selectively connects the signal outputs of the common and balanced signal separation configurations to the VHF aerial input in dependence on monitored characteristics of the radio signals produced at these outputs and received by the vehicle radio receiver.

Abstract: The present invention provides within three particular aspects thereof an isolating and matching device operable to enable an electrically heatable window of a motor vehicle to be used as an efficient VHF communications aerial or antenna; wherein isolating and matching circuitry is provided for Series VHF Matching, Shunt VHF Matching and Split Passband Matching of an electrically heatable window heating element to an aerial input impedance of an aerial feeder circuit of a radio frequency receiver or transmit/receiver device.

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).