Transceiver and antenna system for communication with remote station

• US 6,131,022 A
• Filed: 06/29/1994
• Issued: 10/10/2000
• Est. Priority Date: 06/29/1994
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Martin Marietta Corporation
• Inventors: Benalla, Abdelaziz, Jacomb-Hood, Anthony Wykeham, Berkebile, Jacqueline Jan
• Primary Examiner(s): LE, THANH C
• Application Number:
  US08/267,972
• Time in Patent Office: 2,295 Days
• Field of Search: 455/269, 455/272, 455/273, 455/275, 455/276.1, 455/277.1, 455/277.2, 455/278.1, 455/73, 455/91, 455/101, 455/562, 375/267, 375/347, 375/349, 343/907
• US Class Current: 455/276.1
• CPC Class Codes: H01Q 1/241 used in mobile communications, e.g. GSM H01Q1/247, H01Q1/248 take precedence

Abstract

In one aspect of the present invention, a transceiver includes a pair of antennas with one of the receive channels including a predetermined phase shifter for shifting one of the received signals prior to combining the received electromagnetic energy to form a combined signal for processing by a receiver. The amount of phase shift may be set to maximize the combined signal. The transceiver accounts for signal fading resulting from multiple path reflection, and is especially beneficial in a hand-held or mobile unit. In another aspect, an antenna system includes a pair of elongated quadrifilar antennas, which may be disposed so as to have their longitudinal axes parallel or coincidental as desired. A method for maximizing receipt of electromagnetic energy is also described along with a detector useful for determining the presence of information associated with electromagnetic energy.

Claims

1. A transceiver comprising:

transmitter means having an output, the transmitter for supplying a first electromagnetic energy signal available at the output of the transmitter;

receiver means having an input, the receiver for obtaining communication information associated with a second electromagnetic energy signal;

first antenna means having a port, the first antenna means for intercepting a first portion of the second electromagnetic energy signal for forming a first receive signal, the first receive signal available at the port of the first antenna means, and the first antenna means further for broadcasting a first portion of the first electromagnetic energy signal;

phase shifting means having a first and a second port and an input;

phase control means having an input and an output, the output connected to the input of the phase shifting means;

second antenna means having a port connected to the first port of the phase shifting means, the second antenna means for intercepting a second portion of the second electromagnetic energy signal for forming a second receive signal, the second receive signal available at the port of the second antenna means, and the second antenna means further for broadcasting a second portion of the first electromagnetic energy signal, wherein the phase shifting means for applying a first predetermined phase shift to the second receive signal for forming a phase-shifted receive signal, the phase shifted receive signal available at the second port of the phase-shifting means; and

combiner/divider means having a first, second and third port, the first port connected to the port of the first antenna means, the second port connected to the second port of the phase shifting means and the third port connected to the output of transmitter and to the input of the receiver, the combiner/divider means in a first mode of operation for directing a first part of electromagnetic energy available at the third port to the first port and a second part of electromagnetic energy available at the third port to the second port and in a second mode of operation for combining electromagnetic energy available at the first port and the second port for forming a combined electromagnetic energy signal available at the third port,

wherein the input of the phase control means connected to the third port of the combiner/divider means, the phase control means for generating a phase control signal in response to the magnitude of the combined electromagnetic energy signal, the phase control signal supplied to the input of the phase shifting means and further wherein the first predetermined phase shift in response to the phase control signal.

2. The transceiver as in claim 1, wherein the phase control means further includes peak detector means having an input connected to the third port of the combiner/divider means, the peak detector means for generating a peak detect signal indicative of the magnitude of the combined electromagnetic energy signal available at the third port of the combiner/divider means, wherein the magnitude of the combined electromagnetic energy signal may be maximized in response to the phase control signal.

3. The transceiver as in claim 2, wherein the phase control means further includes state selector means having an output connected to the input of the phase shifting means, the state selector means for commanding application of each of a plurality of second predetermined phase shifts in a predetermined sequence, wherein the one of the plurality of second predetermined phase shifts obtaining a maximum combined electromagnetic energy signal is selected as the first predetermined phase shift.

4. A method for combating multipath fading in a communication system, comprising the steps of:

receiving and transmitting signals via first and second paths and separate respective antennas;

shifting the phase of the signal in the second signal paths relative to the signal in the first path by a fixed amount during transmitting and receiving;

combining the received signals from the first and second path into a combined signal;

detecting whether the combined signal includes a predetermined tone; and

adjusting the fixed amount of phase shift if the predetermined tone is detected.

5. The method according to claim 4, whererin the adjusting comprises the steps of:

initiating at least one change in the fixed amount of phase shift in response to detecting the predetermined tone; and

setting the fixed amount of phase shift in the shifting step based on characteristics of the combined signal during the at least one change.

6. The method according to claim 5, wherein:

the fixed amount of phase shift is set to the fixed amount of phase shift at which the combined signal has the maximum value.

7. The method according to claim 5, wherein:

the fixed amount of phase shift is set to the fixed amount of phase shift at which the combined signal has the lowest signal to noise ratio.

8. A transceiving system for ameliorating multipath fading, comprising:

a transceiver;

first and second antennas coupled to first and second signal paths for receiving and transmitting signals;

a combiner/divider coupled to the transceiver for dividing signals transmitted from the transceiver into the first and second signal paths and for combining signals received from the first and second signal paths into a combined signal for the transceiver;

a phase shifter disposed in the second signal path for shifting a phase of signals in the second signal path a fixed amount relative to signals in the first signal path;

a detector coupled to the transceiver for detecting whether the combined signal includes a predetermined tone;

a control unit connected to the detector and the phase shifter for adjusting the fixed amount of phase shift once the predetermined tone is detected.

9. The transceiver according to claim 8, further comprising:

a state selector coupled to the control unit and the phase shifter, the state selector selecting at least one fixed amount of phase shift in response to the detector detecting the predetermined tone;

a second detector coupled to the combiner/divider, the second detector detecting a characteristic of the combined signal at each selected fixed amount of phase shift; and

a storage table coupled to the second detector, the state selector and the phase shifter for storing and setting the fixed amount of phase shift based on the characteristic of the combined signal during the at least one phase shift selection.

10. The transceiver according to claim 9, wherein:

the second detector is a maximum detector and the fixed amount of phase shift is set to the fixed amount of phase shift at which the combined signal has the maximum value.

11. The transceiver according to claim 9, wherein:

the second detector is a signal to noise detector and the fixed amount of phase shift is set to the fixed amount of phase shift at which the combined signal has the lowest signal to noise ratio.