US 5,334,988 AGranted

Glass antenna for automobile

AssigneesNippon Sheet Glass Co., Ltd., Sumitomo Chemical Company, Limited

InventorsHarunori Murakami, Yuji Baba, Kanta Urakami, Nobuya Niizaki, Hirofumi Natsume, Masato Arisawa

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Abstract

A glass antenna for an automobile uses a coil connected directly to a bus for defogging heaters as an FM subsidiary antenna and a T-shaped impedance matching circuit to provide a monotone change of impedance within the FM frequency band. A reverse T-shaped FM main antenna is employed in conjunction with the FM subsidiary antenna to provide a diversity system to enhance receiving sensitivity in entire directions. The T-shaped matching circuit comprises at least two varactor diodes each applied to a channel selection voltage to match the FM antenna impedance with that of the FM receiver including that of the transmission cable.

Claims6

Dependent claims

A glass antenna for an automobile comprising:

an FM main antenna provided on a window glass of said automobile and having a reverse T-configuration;
an FM subsidiary and AM antenna provided on said window glass and consisting of defogging heaters;
a bus provided on said window glass and connected to said defogging heaters for supplying a defogging current;
a choke coil having a high impedance against AM frequencies;
a coil mounted on said window glass adjacent to said bus, having one end directly connected to said bus to prevent an FM signal from leaking, another end connected to said choke coil, said bus connected to said one end providing an output to FM frequencies;
and
a land provided on said window glass for receiving said defogging current through said choke coil, and said coil being a wireless lead component connected between said bus and said land.

4 more elements

Dependencies are inferred from the claim text.