Claims
- 1. Apparatus for calibrating a transmit antenna array having a plurality of antennas, the transmit antenna array operating at frequencies in the range of 3 to 30 megahertz, each antenna including a row of elements in a log periodic configuration, the apparatus comprising:
- a plurality of probe antennas spaced apart from each other and disposed in one of a near and an intermediate field region of the antenna array for receiving signals transmitted by respective antennas of the array; and
- processing means for determining the location of a phase center of a respective antenna of the array at one selected frequency of transmission by processing a received signal to determine the phase at the probe antennas of the received signal transmitted by the respective antenna of the array, the processing means containing data to indicate the selected phase shift between the respective element and each probe antenna at that selected frequency, a phase sifter being connected to the respective antennas of the array, said processing means being operative to adjust the phase shifter when transmitting at the selected frequency by an amount dependent upon the determined location of the respective phase center.
- 2. Calibration apparatus as claimed in claim 1, in which each antennas of the array comprises at least one dipole, and wherein the processing means compares the phase of the signal received at a probe antenna with an associated expected phase for a respective dipole of the respective antenna of the array, the associated expected phase being based on the frequency and wavelength of transmission, and the distance of the respective dipole from the probe antenna.
- 3. Calibration apparatus as claimed in claim 2, in which the processing means produces an error signal from the received an the expected phases and adjusts the phase shifter connected to the respective antenna of the array in dependence on the error signal.
- 4. Calibration apparatus as claimed in claim 1, wherein each antenna of the array is a log periodic antenna having a boresight and comprising dipoles arranged in a straight line along said boresight, the corresponding dipoles of each antenna of the array being arranged in straight lines with respective dipoles of the other antennas of the array, the bore sights of the antennas of the array being parallel to the one another.
- 5. Calibration apparatus as claimed in claim 1, wherein three probe antennas are provided.
- 6. Calibration apparatus as claimed in claim 4, wherein the probe antennas are arranged in a line broadside to the bore sights of the antennas of the array.
- 7. The apparatus of claim 1 wherein the elements are dipole elements.
- 8. The apparatus of claim 1, wherein the rows of elements are arranged side-by-side and parallel to one another.
- 9. The apparatus of claim 1 wherein the transit antennas array is a phased array.
- 10. A method of calibrating a transmit antenna array having a plurality of antennas, the transmit antennas array operating at frequencies in the range of 3 to 30 megahertz, each antenna including a row of elements in a log periodic configuration, the method comprising:
- taking measurement of the phase of a signal at one selected frequency transmitted by a respective one of the antennas of the array to a plurality of positions spaced apart in one of a near and an intermediate field region of the antenna array;
- determining the location of a phase center of the respective one of the antennas from the measurements utilizing data indicating the excited phase shift between the respective element and each probe antenna at that selected frequency; and
- applying an off-set to the phase of the signal transmitted by the respective one of the antennas dependent on the determined location of the phase center.
- 11. An antenna array comprising:
- a plurality of transmit antennas for transmitting signals, each transmit antenna being operatively connected to one of a like plurality of phase shifters, each phase shifter being connected to an associated amplifier and transmitter;
- a plurality of probe antennas disposed to receive signals transmitted form the transmit antennas;
- processing means connected to each of the phase shifters and connected to the probe antennas, for determining the location of a phase center of a respective transit antenna at on selected frequency of transmission by processing a received signal to determine the phase at the probe antennas of the received signal transmitted by the respective transmit antenna, and for controlling the phase shifters based on the determined location of the respective phase center, the processing means containing data to indicate the expected phase shift between the respective element and each probe antenna at that selected frequency;
- wherein the transmit antennas each comprise a plurality of dipoles in a log periodic configuration.
- 12. The antenna array according to claim 11, wherein three probe antennas are provided.
Priority Claims (1)
Number |
Date |
Country |
Kind |
8919623 |
Aug 1989 |
GBX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/569,130, filed Aug. 17, 1990, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (6)
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Sep 1982 |
EPX |
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SUX |
1394166 |
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SUX |
Non-Patent Literature Citations (3)
Entry |
IEEE, Test Procedure for Antennas pp. 1-3 and 15-17 Jan. 15, 1965 IEEE No. 149. |
Translation of SU Patent Document 1334231, Seryakov et al., Aug., 1987, 7 pp. |
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Continuations (1)
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Number |
Date |
Country |
Parent |
569130 |
Aug 1990 |
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