Wireless microphone

• US 4,344,184 A
• Filed: 07/31/1980
• Issued: 08/10/1982
• Est. Priority Date: 07/31/1980
• Status: Expired due to Term

• Current Assignee: Telex Communications Incorporated (Robert Bosch GmbH)
• Original Assignee: Cetec Corp.
• Inventors: Edwards, Robert R.
• Primary Examiner(s): Bookbinder, Marc E.
• Application Number:
  US06/174,153
• Time in Patent Office: 740 Days
• Field of Search: 455/89, 455/90, 455/95, 455/100, 455/128, 455/129, 455/127, 343/702
• US Class Current: 455/95
• CPC Class Codes: H04B 1/04 Circuits

Abstract

A wireless microphone which does not require a separate antenna. A wireless microphone in the form of an elongate housing of nonelectrical conducting material with a microphone unit mounted in one end of the housing and a battery and control switch mounted in the other end of the housing. A first electrical circuit including an audio amplifier and a second electrical circuit including a radio frequency amplifier are mounted in the housing physically separated from each other and interconnected by radio frequency chokes. The output of the radio frequency amplifier is connected to circuit ground of the audio amplifier, with the microphone unit and first circuit serving as one radiator of a dipole and with the battery and second circuit serving as the other radiator of the dipole.

Claims

1. In a wireless microphone, the combination of:

an elongated housing of electrically nonconducting material;

a microphone unit mounted in one end of said housing;

a first electrical circuit including an audio amplifier;

a second electrical circuit including a radio frequency amplifier;

a plurality of radio frequency chokes interconnecting said first and second electrical circuits;

a conductor connecting the output of said radio frequency amplifier to said audio amplifier; and

means for mounting said first and second circuits in said housing spaced from each other with said chokes positioned in the space between said circuits, with said first circuit mounted intermediate said microphone unit and said second circuit, with the electrical components of said first circuit comprising at least part of one radiator of a dipole and the electrical components of said second circuit comprising at least part of the other radiator of said dipole.

2. A wireless microphone as defined in claim 1 wherein said audio amplifier has a first circuit ground, and said radio frequency amplifier output is connected to said first circuit ground.

3. A wireless microphone as defined in claim 1 wherein said first and second circuits are formed on a printed circuit board mounted within said housing, with said circuits separated axially on said board by a gap, and with said radio frequency chokes positioned in said gap between said first and second circuits.

4. A microphone unit as defined in claim 3 with a battery and an on-off switch mounted at another end of said housing and connected to said second circuit, and

wherein said microphone unit includes a protective screen and said audio amplifier has a first circuit ground, with said screen connected to said first circuit ground.

5. In a wireless microphone, the combination of:

an elongated housing of electrically nonconducting material;

a microphone unit mounted in one end of said housing;

a first electrical circuit including an audio amplifier having a first circuit ground;

a second electrical circuit including a radio frequency amplifier having a second circuit ground;

a plurality of radio frequenty chokes interconnecting said first and second electrical circuits,

said plurality of chokes including a first choke connected between said first and second grounds and a second choke connected between said first circuit output and said second circuit input;

a conductor connecting the output of said radio frequency amplifier to said first circuit ground of said audio amplifier; and

means for mounting said first and second circuits in said housing with said first circuit mounted intermediate said microphone unit and said second circuit, with said first circuit comprising at least part of one radiator of a dipole and said second circuit comprising at least part of the other radiator of said dipole.

6. A wireless microphone as defined in claim 5 including a feedback connection from said second circuit to said first circuit, and

wherein said plurality of chokes includes a third choke in said feedback connection.

7. A wireless microphone as defined in claim 6 including a battery power supply mounted in said housing, and

wherein said plurality of chokes includes a fourth choke connected between said battery and said first circuit.

8. A wireless microphone as defined in claim 7 including a gain control resistor, and

wherein said plurality of chokes includes a fifth choke connected between said gain control resistor and said first circuit.

9. In a wireless microphone, the combination of:

an elongated housing of electrically nonconducting material;

a microphone unit mounted in one end of said housing;

a first electrical circuit including an audio amplifier;

a second electrical circuit including a radio frequency amplifier;

a plurality of radio frequency chokes interconnecting said first and second electrical circuits;

a conductor connecting the output of said radio frequency amplifier to said audio amplifier;

means for mounting said first and second circuits in said housing with said first circuit mounted intermediate said microphone unit and said second circuit; and

a battery mounted in another end of said housing and connected to said second circuit by an off-on switch and connected to said first circuit through one of said radio frequency chokes;

said microphone unit and first circuit comprising at least part of one radiator of a dipole and said battery and second circuit comprising at least part of other radiator of said dipole.

10. In a wireless microphone, the combination of:

an elongated housing of electrically nonconducting material;

a microphone unit mounted in one end of said housing;

a first electrical circuit including an audio amplifier;

a second electrical circuit including a radio frequency amplifier;

a plurality of radio frequency chokes interconnecting said first and second electrical circuits;

a conductor connecting the output of said radio frequency amplifier to said audio amplifier;

means for mounting said first and second circuits in said housing with said first circuit mounted intermediate said microphone unit and said second circuit, with said first circuit comprising at least part of one radiator of a dipole and said second circuit comprising at least part of the other radiator of said dipole;

said first and second circuits formed on a printed circuit board mounted within said housing, with said circuits separated axially on said board by a gap, and with said radio frequency chokes positioned in said gap; and

a battery and an on-off switch mounted at another end of said housing and connected to said second circuit;

said microphone unit including a protective screen and said audio amplifier having a first circuit ground, with said screen connected to said first circuit ground.