Communications: radio wave antennas – Antennas – Measuring signal energy
Reexamination Certificate
2000-08-23
2001-12-04
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Measuring signal energy
C343S850000
Reexamination Certificate
active
06326929
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and a device to measure the impedance of radioelectric antennas carrying out high-frequency transmission in a broad bandwidth.
The use of a broadband antenna in transmission requires the positioning of a matching device between the transmitter and the antenna in order to match the output impedance of the amplifier that powers the antenna with the characteristic impedance of the antenna.
The matching device is usually controlled by successive approximations with checks being made each time on the standing-wave ratio and the phase of the signal at the input of the device. The matching is done when the standing-wave ratio has descended below a given threshold value.
The execution of such a process requires a large number of iterative operations that take time and delay the transmission of the useful signal accordingly.
In addition, the devices implemented to measure the standing-wave ratio are rudimentary and, since they are sized in order to work in broad frequency bands, transmitters that are geographically nearby can always disturb the measurements because of their lack of selectivity.
SUMMARY OF THE INVENTION
The aim of the invention is to mitigate the above-mentioned drawbacks.
To this end, an object of the invention is a method to measure the impedance of an antenna supplied by an amplifier, wherein the method consists of:
the conversion, into voltage, of the value of the antenna supply current by means of a transformer whose primary winding is crossed by the supply current,
the uncoupling, in a first step, of the antenna from the amplifier to charge the amplifier on a calibrating resistor Re through the primary winding of the transformer in making the voltage given by the secondary winding equal to the voltage given by the output of the amplifier,
then the uncoupling, in a second step, of the calibrating resistor Re from the output of the amplifier by reconnecting the antenna to the output of the amplifier through the primary winding of the transformer to compute the modulus and the argument of impedance Z of the antenna through the multiplication, by the value of the calibrating resistor Re, of the ratio of the voltages given respectively during this second step by the output of the amplifier and the secondary winding of the transformer.
An object of the invention is also a device for the implementation of the above-mentioned method.
REFERENCES:
patent: 4027332 (1977-05-01), Wu et al.
patent: 4380767 (1983-04-01), Goldstein et al.
patent: 4409544 (1983-10-01), Redlich
patent: 5157338 (1992-10-01), Motherbaugh et al.
patent: 5206600 (1993-04-01), Moehlmann
patent: 29 31 757 (1981-02-01), None
patent: 197 56 100 A 1 (1998-10-01), None
patent: 10 163889 (1998-06-01), None
patent: WO 96/39727 (1996-12-01), None
"Thomson-CSF"
Nguyen Hoang
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Wong Don
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