Method for improving power measurement implemented with a directional coupler at low power levels
First Claim
1. A directional coupler arrangement for measuring radio frequency power, which directional coupler arrangement comprisesa directional coupler comprising a first conductor element (1) and a second conductor element (2), both of which comprise a first end and a second end,a detector element (4) for detecting a level of power coupled from the first conductor element (1) to the second conductor element (2) and for providing an output signal as a response to said power level, which detector element comprises an input port and an output port and whose input port is connected to the first end of the second element (2), anda terminal impedance (12), which is connected between the second end of the second conductor element (2) and an earth potential,characterized in thatthe impedance value of said terminal impedance (12) is altered electrically by means of a control signal fed to it.
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Accused Products
Abstract
The invention relates to a directional coupler arrangement and measurement of radio frequency electric power with a directional coupler arrangement, which arrangement comprises a directional coupler, in which a terminal impedance, a detector element and a control circuit are connected between the end of the second conductor element and the earth potential. The impedance value of the terminal impedance can be altered by means of an electric control signal and said control circuit produces said control signal on the basis of the signal provided by the detector element. When the detected power level is low, the control circuit increases the impedance value of the terminal impedance, whereby the peak voltage of the signal applied to one end of the directional coupler increases and the arrangement yields a measurement result that is larger than ordinary, which improves the accuracy and reliability of the arrangement at low power levels.
86 Citations
15 Claims
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1. A directional coupler arrangement for measuring radio frequency power, which directional coupler arrangement comprises
a directional coupler comprising a first conductor element (1) and a second conductor element (2), both of which comprise a first end and a second end, a detector element (4) for detecting a level of power coupled from the first conductor element (1) to the second conductor element (2) and for providing an output signal as a response to said power level, which detector element comprises an input port and an output port and whose input port is connected to the first end of the second element (2), and a terminal impedance (12), which is connected between the second end of the second conductor element (2) and an earth potential, characterized in that the impedance value of said terminal impedance (12) is altered electrically by means of a control signal fed to it.
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8. A directional coupler arrangement for measuring radio frequency power, which directional coupler arrangement comprises a directional coupler comprising a first conductor element (1) and a second conductor element (2), both of which comprise a first end and a second end,
a detector element (4) for detecting a level of power coupled from the first conductor element (1) to the second conductor element (2) and for providing an output signal as a response to said power level, which detector element comprises an input port and an output port and whose input port is connected to the first end of the second element (2), and a terminal impedance (12), which is connected between the second end of the second conductor element (2) and an earth potential, characterized in that the impedance value of said terminal impedance (12) is altered electrically by means of a control signal fed to it, and further characterized in that said directional coupler arrangement comprises a control circuit (11) between said detector element (4) and said terminal impedance (12) for forming said control signal on the basis of the output signal of the detector element.
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9. A method for measuring the radio frequency power of a transmitter with a directional coupler arrangement, wherein the directional coupler arrangement comprises a directional coupler having a first conductor element and a second conductor element, the first conductor element being disposed within a transmission path of the transmitter, the second conductor element having a first end and a second end, the first end of the second conductor element being electrically connected to the transmitter and defining a first branch, the second end of the second conductor being electrically terminated at an earth potential and defining a second branch, the method comprising the steps of:
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detecting a power level at the first branch using a detector disposed between the first end of the second conductor and the transmitter; forming an output signal based upon the detected power level of the first branch; and electrically altering an impedance value of a terminal impedance of the directional coupler measured at the second end of the second conductor. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification