The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 13, 1978
Filed:
Feb. 22, 1977
James O Elliott, Xenia, OH (US);
General Motors Corporation, Detroit, MI (US);
Abstract
An antenna for simultaneous connection to a citizen's band transceiver, an AM receiver and a FM receiver, particularly suitable for use on a vehicle such as an automobile. The antenna proper is a center-loaded upstanding rod which, in the preferred form, telescopes downwardly to a retracted position where it does not protrude above the ground plane. The antenna proper is connected to a T-connected open stub transmission line and to a FM resonant relatively high impedance signal-carrying transmission line. The former has inductive reactance in the FM band which offsets the capacitive reactance of the relatively short effective length of the antenna proper in the FM frequencies. The signal-carrying transmission line is substantially half wave in length in the FM band so as to reflect impedance at its far end substantially equal to the impedance present at the T-connection. The signal-carrying transmission line is also of length that provides resonant action transforming the relatively low impedance at the T-connection or base of the antenna in the CB band to a higher impedance, such as 50 ohms, at the end of that transmission line. Finally, the signal-carrying transmission line, because of its relatively high characteristic impedance, has very low capacitance and therefore does not tend to load the AM radio. The end of the signal-carrying transmission line is connected to the input terminal of splitter containing resonant circuits which are in turn connected to two transmission lines, one leading to the CB transceiver and the other leading to the AM/FM radio.