Single-block filter for antenna duplexing and antenna-switched diversity

• US 5,241,693 A
• Filed: 02/19/1992
• Issued: 08/31/1993
• Est. Priority Date: 10/27/1989
• Status: Expired due to Term

• Current Assignee: CTS Corporation
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Kommrusch, Richard S., Kim, Jin D., Moutrie, Michael F.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): URBAN, EDWARD F
• Application Number:
  US07/840,597
• Time in Patent Office: 559 Days
• Field of Search: 455/78, 455/80, 455/82, 455/83, 455/84, 455/134, 455/135, 455/277.1, 455/277.2, 333/202, 333/206, 333/207, 333/222
• US Class Current: 455/82
• CPC Class Codes: H04B 1/52 Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
• CPC Class Codes: H04B 7/0802 using antenna selection H04B7/0868 takes precedence; antenna beam directivity switching H01Q3/24

Abstract

A single-block ceramic filter (102) is coupled to two antennas (142 and 144) for providing both antenna duplexing and antenna-switched diversity in a duplex radio transceiver (100). One antenna (142) is coupled by the filter (102) to a transmitter (132), and both antennas (142 and 144) are switchably coupled by the filter (102) to a receiver (130) by diversity control circuitry (101) in response to a diversity control signal (137). A microcomputer (134) in the transceiver (100) is coupled to the receiver (130) for monitoring the received signal strength (135). When the received signal strength (135) drops in level indicating that the signal being received on one of the antennas (142 or 144) has become degraded due to fading or other interference, the microcomputer (134) changes the binary state of the diversity control signal (137) for switching the receiver (130) to the other one of the antennas (142 or 144 ).

Claims

1. A filter for coupling a transmitter to a first antenna and coupling a receiver to the first antenna and, in response to a control signal from a signal source, coupling the receiver to a second antenna, said filter comprising:

a dielectric block comprised of a dielectric material, having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;

a first coupler coupling the transmitter to said first hole;

a second coupler coupling the first antenna to said second hole;

a third coupler for coupling said third hole to signal ground in response to the control signal and substantially isolating the first and second holes from the fourth and fifth holes, thereby isolating the receiver from the first antenna;

a fourth coupler for coupling said fourth hole to the second antenna in response to the control signal; and

a fifth coupler for coupling said fifth hole to the receiver.

2. The filter of claim 1, wherein said third coupler includes switching circuitry responsive to the control signal for switching said third hole to signal ground.

3. The filter of claim 2, wherein said switching circuitry includes a pin diode.

4. The filter of claim 1, wherein said fourth coupler includes switching circuitry responsive to the control signal for switching said fourth hole between the second antenna and signal ground.

5. The filter of claim 4, wherein said switching circuitry includes a pin diode.

6. A radio, comprising:

a first antenna;

a second antenna;

a transmitter having an output;

a receiver having an input;

control circuitry coupled to the transmitter and receiver and producing a control signal;

a filter for coupling the transmitter to the first antenna and coupling the receiver to the first antenna and, in response to the control signal, coupling the receiver to a second antenna, said filter comprising;

a dielectric block comprised of a dielectric material, having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;

a first coupler coupling the output of the transmitter to said first hole;

a second coupler coupling the first antenna to said second hole;

a third coupler for coupling said third hole to signal ground in response to the control signal and substantially isolating the first and second holes from the fourth and fifth holes, thereby isolating the receiver from the first antenna;

a fourth coupler for coupling said fourth hole to the second antenna in response to the control signal; and

a fifth coupler for coupling said fifth hole to the input of the receiver.

7. The radio of claim 6, wherein said third coupler includes switching circuitry responsive to the control signal for switching said third hole to signal ground.

8. The radio of claim 7, wherein said switching circuitry includes a pin diode.

9. The radio of claim 6, wherein said fourth coupler includes switching circuitry responsive to the control signal for switching said fourth hole between the second antenna and signal ground.

10. The radio of claim 9, wherein said switching circuitry includes a pin diode.

11. The radio of claim 6, wherein said receiver includes signal strength circuitry for producing an output signal having a magnitude related to the strength of signal received by said receiver, and said control circuitry includes processing circuitry coupled to the output signal of the receiver for producing a first binary state of the control signal when the output signal of the receiver has a magnitude at least as great as a predetermined magnitude and a second binary state of the control signal when the output signal of the receiver has a magnitude less than the predetermined magnitude.

12. The radio of claim 11, wherein said processing circuitry samples the output of the receiver at least once every predetermined time interval and thereafter produces the first or second binary state of the control signal.

13. A filter for coupling a transmitter to a first antenna and coupling a receiver to the first antenna and, in response to a control signal from a signal source, coupling the receiver to a second antenna, said filter comprising:

a dielectric block comprised of a dielectric material, having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;

a first coupler having an electrode extending at least partially into said first hole for coupling said first hole to the transmitter;

a second coupler having an electrode extending at least partially into said second hole for coupling said second hole to the first antenna;

a third coupler having an electrode extending at least partially into said third hole for coupling said third hole to signal ground in response to the control signal and substantially isolating the first and second holes from the fourth and fifth holes, thereby isolating the receiver from the first antenna;

a fourth coupler having an electrode extending at least partially into said fourth hole for coupling said fourth hole to the second antenna in response to the control signal; and

a fifth coupler having an electrode extending at least partially into said fifth hole for coupling said fifth hole to the receiver.

14. A radio, comprising:

a first antenna;

a second antenna;

a transmitter having an output;

a receiver having an input;

control circuitry coupled to the transmitter and receiver and producing a control signal;

a filter for coupling the transmitter to the first antenna and coupling the receiver to the first antenna and, in response to the control signal, coupling the receiver to a second antenna, said filter comprising;

a dielectric block comprised of a dielectric material, having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;

a first coupler having an electrode extending at least partially into said first hole for coupling said first hole to the transmitter;

a second coupler having an electrode extending at least partially into said second hole for coupling said second hole to the first antenna;

a third coupler having an electrode extending at least partially into said third hole for coupling said third hole to signal ground in response to the control signal and substantially isolating the first and second holes from the fourth and fifth holes, thereby isolating the receiver from the first antenna;

a fourth coupler having an electrode extending at least partially into said fourth hole for coupling said fourth hole to the second antenna in response to the control signal; and

a fifth coupler having an electrode extending at least partially into said fifth hole for coupling said fifth hole to the receiver.

15. A filter for filtering first and second signals from first and second signal sources to produce filtered first and second signals, respectively, said filter comprising:

a dielectric block comprised of a dielectric material, having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;

a first coupler coupling the first signal to said first hole;

a second coupler coupling the filtered first signal from said second hole;

a third coupler for coupling said third hole to signal ground and substantially isolating the first and second holes from the fourth and fifth holes, thereby isolating the first signal from the second signal;

a fourth coupler for coupling the second signal to said fourth hole; and

a fifth coupler for coupling the filtered second signal from said fifth hole.

16. A radio, comprising:

an antenna;

a transmitter having an output;

a receiver having an input;

a filter for coupling the transmitter to the antenna and coupling the receiver to the antenna, said filter comprising;

a dielectric block comprised of a dielectric material, having top, bottom and side surfaces and having at least first, second, third, fourth and fifth holes each extending from the top surface toward the bottom surface and aligned with one another, said bottom and side surfaces and said five holes being substantially covered with a conductive material;

a first coupler coupling the output of the transmitter to one of said first hole and said second hole;

a second coupler coupling the antenna to the other of said first hole and said second hole;

a third coupler for coupling said third hole to signal ground and substantially isolating the first and second holes from the fourth and fifth holes, thereby isolating the receiver from the transmitter;

a fourth coupler for coupling one of said fourth hole and said fifth hole to the antenna; and

a fifth coupler for coupling the other of said fourth hole and said fifth hole to the input of the receiver.