Radio frequency multiplexer for coupling antennas to AM/FM/WB, CB/WB, and cellular telephone apparatus

• US 6,297,711 B1
• Filed: 10/19/1999
• Issued: 10/02/2001
• Est. Priority Date: 08/07/1992
• Status: Expired due to Fees

• Current Assignee: R.A. Miller Industries, Inc.
• Original Assignee: R. A. Phillips Industries Incorporated
• Inventors: Seward, Glen J., Bogdans, Paul A.
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): Summons, Barbara
• Application Number:
  US09/420,233
• Time in Patent Office: 714 Days
• Field of Search: 333/129, 333/132, 333/124-126
• US Class Current: 333/129
• CPC Class Codes: H01Q 1/3266 using the mirror of the vehicle
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 5/321 within a radiating element or between connected radiating elements
• CPC Class Codes: H01Q 5/50 Feeding or matching arrangements for broad-band or multi-band operation
• CPC Class Codes: H01Q 9/32 Vertical arrangement of element H01Q9/40 takes precedence

Abstract

An AM/FM/WB/CB/cellular telephone antenna includes a first frequency self-resonant circuit at a position above the lower end of the antenna such that the electrical length of the lower section of the antenna is equivalent to one-quarter wavelength for a frequency in the FM frequency range and a second frequency self-resonant circuit disposed below the first frequency self-resonant circuit. The first self-resonant circuit presents a high impedance in the FM frequency band and the second self-resonant circuit presents a high impedance in the cellular frequency range. The entire length of the antenna is equivalent to one-quarter wavelength in a frequency in the CB frequency band. The antenna wire is wound around a fiberglass core, and the FM self-resonant circuit is formed by a tightly wound, coiled section of the wire together with a thin-walled brass tube extending over the core in the area of the tightly wound section. A thin dielectric film is applied between the tube and the tightly wound section of antenna wire thereby forming a capacitor. Two antennas, each comprising two frequency self-resonant circuits, are connected by means of a multiplexing circuit to AM/FM/WB, CB/WB and cellular telephone apparatus.

Claims

1. A multiplexer circuit for coupling an antenna to CB radio apparatus operative in a CB frequency range and a weather band frequency range, the multiplexer circuit comprising:

an input conductor connected to the antenna and a first output conductor for connection to the CB radio apparatus;

a first series L-C circuit connected between the input conductor and the first output conductor and comprising a first inductor and a first capacitor connected in series with the first inductor and providing a blocking impedance to signals outside of the CB frequency range; and

a second series L-C circuit connected in parallel with the first series L-C circuit and comprising a second inductor and a second capacitor connected in series with the second inductor and providing a blocking impedance to signals outside of the weather band frequency range.

2. The multiplexer in accordance with claim 1 and further comprising circuitry for coupling the antenna to FM/WB radio apparatus operative in an FM frequency range and the weather band frequency range, and a second output conductor for connection to the FM/WB radio apparatus.

3. The multiplexer circuit in accordance with claim 1 and further comprising a capacitor connected between said first output terminal and a system ground and a parallel L-C circuit connected in series with said capacitor for blocking signals having frequencies falling in the weather band frequency range.

4. A multiplexer circuit for selectively coupling an antenna to CB radio apparatus and to FM radio apparatus and to cellular telephone apparatus, the multiplexer circuit comprising:

an input conductor for connection to the antenna;

a first output conductor for connection to the CB radio apparatus;

a second output conductor for connection to the FM radio apparatus;

a third output conductor for connection to the cellular radio apparatus; and

a series L-C circuit connected between the input conductor and the first output conductor and comprising a first inductor and a first capacitor connected in series and providing a blocking impedance to signals in the FM frequency range.

5. The multiplexer circuit in accordance with claim 4 and further comprising a parallel L-C circuit connected between the input conductor and the second output conductor for blocking signals in the CB frequency range and an additional inductor connected in series with the parallel L-C circuit for blocking signals in the cellular frequency range.

6. The multiplexer circuit in accordance with claim 5 and further comprising a capacitor connected between the input conductor and the third output conductor for blocking lower frequency signals in the CB and AM/FM frequency ranges.