Abstract: A method of emulating real world conditions of a radio frequency (RF) signal reaching a device-under-test (DUT) includes exposing the DUT to a cone of RF signal angles of arrival transmitting coordinated RF signals from an antenna array. The antenna array has at least one antenna located at a center of the antenna array and at least three antennas located at substantially equal distance from the center and from each other. Such configuration of the antennas in the antenna array defines a base of the cone to have a range of angles of 20° to 70°. The cone of RF signal angles of arrival and the DUT may be enclosed in a chamber such as an anechoic chamber. The method sets an azimuth angle and/or an elevation angle of the DUT with respect to the transmitted RF signals.

Abstract: A technique for improving radio coverage involves using interdependently tuned directional antennas. An example according to the technique is a substrate including two antennas, a transceiver, and a connector. Another example system according to the technique is a wireless access point (AP) including a processor, memory, a communication port, and a PCB comprising a plurality of directional antennas and a radio. An example method according to the technique involves determining a voltage standing wave ratio (VSWR) and interdependently tuning a first and second directional antenna to reach an expected radiation pattern.

Abstract: A first adjustment circuit adjusts an impedance of a first antenna, and a second adjustment circuit adjusts an impedance of a second antenna. A coupling reduction circuit reduces an amount of coupling of the first and second antennas. A first reception power measurement unit measures first reception power received from the first antenna, and a second reception power measurement unit measures second reception power received from the second antenna. A selection unit selects a circuit from among the first adjustment circuit, the second adjustment circuit, and the coupling reduction circuit. A circuit control unit controls the impedance of the selected circuit so that the value of the evaluation function proportional to the product of the first reception power and the second reception power becomes larger.

Abstract: A test fixture for performing RF testing. The test fixture includes a base plate configured to support an electronic device. The base plate defines a grid of grooves. The base plate further defines a cut-out configured to receiving an antenna in one or more positions. The test fixture further includes markers indicating positioning of the electronic device on the base plate.

Abstract: Various antenna assemblies are disclosed. In one example, an antenna assembly includes a reflector including a first ground plane, a second ground plane below and spaced apart from the reflector, an antenna adjacent a surface of the reflector opposite the second ground plane, and a grounding post galvanically connecting the first ground plane and the second ground plane.

Abstract: An antenna measurement and control system for use with a transmitting antenna, the system comprising a sensor configured to determine an indication of the radiation emitted by the antenna; control circuitry connectable to the antenna and configured to selectively vary, or disengage, the power supplied to the antenna, and a processor connectable to the sensor and control circuitry, wherein the processor is configured to control the control circuitry in response to the determined indication of the emitted radiation.

Abstract: A method is provided for detecting scrambling of a radiocommunication network. The method is applied by a radiocommunication circuit capable of being connected to the network by being synchronized on a radiocommunication channel. The method includes a final detection phase, having the following steps: detection of verification of the following final condition: there are N radiocommunication channels on which the radiocommunication circuit cannot be synchronized despite detection of a power level normally sufficient for being synchronized, where N>2; and if the final condition is verified, generation of a final scrambling signal with a probability of scrambling equal to 100%. The method also includes at least one intermediate detection phase, having the following steps: detection of verification of at least one intermediate condition; and if the at least one intermediate condition is verified, generation of an intermediate scrambling signal with a probability of scrambling of less than 100%.

Abstract: A radio-frequency test system configured for testing device structures under test is provided. The test system may include a radio-frequency tester, a test probe that is coupled to the tester, and an auxiliary test fixture that receives the device structures under test. During testing, the device structures under test may be mounted on the auxiliary test fixture. The auxiliary test fixture may provide a ground contact point and a ground reference plane. The device structures under test may include a radio-frequency circuit coupled to a conductive member via a signal path. During testing, the test probe may mate with the conductive member on the device structures under test and the ground contact point on the auxiliary test fixture. The ground reference plane in the auxiliary test fixture may serve to provide proper grounding for the signal path to help improve the accuracy of test results associated with the radio-frequency circuit.

Abstract: A high-frequency measurement setup for measuring a high-frequency test object, in particular, an antenna is provided. The setup includes one or more reflectors for high-frequency signals, a laser tracker, retrotargets for laser beams of the laser tracker that are disposed on the reflectors and are provided to orient the high-frequency test object, and a measuring unit that is designed to actuate the laser tracker in such a way that the high-frequency test object and one or more reflectors are measured in terms of their propagation of high-frequency signals.

Abstract: An antenna arrangement is provided, which includes first and second antenna elements. A feeder line connects the first and second antenna elements for feeding a signal to and from the first and second antenna elements and the signal is inductively coupled between the feeder line and a calibration line so it can be fed to measurement equipment.

Abstract: A radiation detector disposed on a microwave antenna assembly is disclosed. The radiation detector includes a receiving antenna adapted to receive errant microwave energy and a rectifier coupled to the receiving antenna that is adapted to rectify at least a portion of the errant microwave energy. A filter is coupled to the rectifier and is adapted to convert the rectified microwave energy into a detection signal.

Abstract: In an automatic tuning system for a loop antenna having a single electronically variable reactance element, the reactive component sense of the antenna impedance is determined over a wide range of frequency. The electronically variable reactance component of the antenna is automatically minimized by a feedback loop driving a voltage variable capacitance until the reactive component of the antenna impedance is virtually zero and the antenna impedance is hence resistive. The adjustment of the electronically variable capacitance is by a variable high voltage power supply controlled by a feedback amplifier or by a high voltage feedback amplifier.

Abstract: An electronic device includes a radio frequency module having a communication port, and an antenna module having a number of antennas electrically coupled to the communication port. A method of reducing specific absorption rate (SAR) for the electronic device includes: a) measuring the SAR for the electronic device to obtain a measurement result; b) increasing the number of antennas of the antenna module when the measurement result is not lower than a standard value; and c) repeating steps a) and b) until the measurement result is equal to or smaller than the standard value.

Abstract: A radiated power detection apparatus including a reception antenna and a probe in a Fresnel zone determines a measurement parameter of a wireless communication device and coincides central points of an antenna that is included in the wireless communication device, the reception antenna, and the probe. Next, the radiated power detection apparatus measures the magnitude of an electric field corresponding to at least one measurement point while transferring the reception antenna and the probe according to a measurement parameter, calculates the magnitude of a maximum electric field in a far-field using the magnitude of an electric field, and thus detects radiated power of the wireless communication device based on the magnitude of a maximum electric field.

Abstract: An apparatus for measuring radiated power of an antenna includes a chamber which an absorber is attached to a wall thereof; a source antenna and a test antenna configured to be arranged within the chamber; a rotational axis configured to adjust an arrangement angle of the test antenna in up-and-down directions; and a roll positioner configured to rotate the test antenna. Further, the apparatus includes a turntable configured to be provided within the chamber and be rotated in a left-to-right direction; a connection unit configured to allow the test antenna, to rotate in the left-to-right direction; and a supporting unit configured to be rotatably connected to one end of the rotational axis which the other end thereof is rotatably connected to the roll positioner.

Abstract: One embodiment provides a system that analyzes a target electromagnetic signal radiating from a monitored system. During operation, the system monitors the target electromagnetic signal using a near-isotropic antenna that includes a set of receiving surfaces arranged in a regular polyhedron. Next, the system obtains a set of received target electromagnetic signals from the receiving surfaces. Finally, the system assesses the integrity of the monitored system by separately analyzing each of the received target electromagnetic signals.

Abstract: An electromagnetic environment simulation method. Embodiments of the invention provide for nanosecond or better time resolution and milliradian angular resolution simulation of the dynamic electromagnetic environment of a wireless system under test.

Abstract: In a method of measuring a radiation power generated from a DUT from an output of a measurement antenna, wherein the DUT is arranged in an ellipsoid enclosed space such that a radiation center of the radio wave is substantially coincided with the neighborhood of a first focal point. The radio wave radiated from the DUT and reflected from the wall surface is received by a receiving antenna arranged in the neighborhood a second focal point thereby to measure the total radiated power of the DUT from the output signal of the receiving antenna. One of the DUT and the receiving antenna is moved along the axis passing through the first and second focal points, and based on the measurement value maximizing the output signal power of the receiving antenna, calculating the total radiated power of the DUT.

Abstract: A method, apparatus and system providing power to Low Noise Block Amplifiers (LNBs) in a satellite signal receiving system wherein at least one receiver provides power to the LNBs. A system in accordance with the present invention comprises a first stage of power regulation, coupled to the at least one receiver in a respective fashion, wherein the first stage of power regulation comprises linear regulation, and a second stage of power regulation, coupled between the first stage of power regulation and the LNBs, wherein the second stage of power regulation comprises a switching power regulator. Another embodiment of the present invention comprises a first stage of power regulation, coupled to the at least one receiver in a respective fashion, wherein the first stage of power regulation comprises a switching power regulator, and a second stage of power regulation, coupled between the first stage of power regulation and the LNBs, wherein the second stage of power regulation comprises a linear regulator.

Abstract: An electronic device may have tunable antenna structures. A tunable antenna may have an antenna resonating element and an antenna ground. An adjustable electronic component such as an adjustable capacitor, adjustable inductor, or adjustable phase-shift element may be used in tuning the antenna. An impedance matching circuit may be coupled between the tunable antenna and a radio-frequency transceiver. The adjustable electronic component may be coupled to the antenna resonating element or other structures in the antenna or may form part of the impedance matching circuit, a transmission line, a parasitic antenna element, or other antenna structures. During manufacturing, manufacturing variations may cause the performance of the tunable antenna to deviate from desired specifications. Calibration operations may be performed to identify compensating adjustments to be made with the adjustable electronic component.

Abstract: A scanning measurement apparatus and method comprising a device under test for receiving or transmitting a signal, a measurement probe, a robot for moving the device or the probe relative to one another to scan continuously over a two-dimensional planar, cylindrical or spherical surface in a three-dimensional space, and a controller for obtaining measurement samples at generalized grid points on the two-dimensional surface computing characteristic coefficients from the measured values, wherein the characteristic coefficients are recovered using a conjugate gradient method, using in part an unequally spaced fast Fourier transform or using a conjugate gradient method and an unequally spaced fast Fourier transform.

Abstract: The invention relates to a method for electromagnetic testing of an object, a method in which electromagnetic radiation is sent by a probe (2) in a determined principal aiming direction (D) towards a determined test point (40) where the object (OT) is located. The invention is defined in that the probe (2) and a support (104) for the object (OT) are moved relative to each other by a mechanical displacement device (60) according to a movement representative of a predetermined angular spread statistic relative to the principal aiming direction (D) to generate electromagnetic radiation having this predetermined angular spread statistic relative to the principal aiming direction (D) by the probe (2).

Abstract: An electromagnetic radiation measuring device includes a test antenna module and a main processor electrically connected to the test antenna module. The test antenna module includes a plurality of pre-test antennas and at least one final test antenna, which have predetermined polarities and are positioned at predetermined heights, respectively. The pre-test antennas and the final test antenna respectively receive wireless signals sent from an electronic device. The main processor measures and records a frequency of the strongest wireless signal received by selected ones of the pre-test antennas that have the same polarity, and further determines whether power of wireless signals at the recorded frequency received by the final test antenna polarized to have the same polarity as that of the selected ones of the pre-test antennas exceeds a predetermined acceptable range.

Abstract: A wireless communications validation system comprises a validation module configured to determine an identity of an antenna disposed in a computer system and an identity of a wireless module disposed in the computer system, the validation module configured to validate permissible combination of the antenna with the wireless module.

Abstract: An antenna radiation pattern measurement device that measures a radiation pattern of an AUT by using a source antenna includes a control unit, an analysis unit, and a measurement unit. The control unit controls driving of the source antenna and the AUT. The analysis unit measures an electric field value from a radio frequency (RF) signal that is transmitted from one of the source antenna and the AUT and received by the other antenna. In addition, the measurement unit controls the control unit and the analysis unit and measures a radiation pattern of the AUT by using the electric field value.

Abstract: Antenna enclosure apparatus are provided that may be used to verify the signal path integrity, amplitude and/or phase of a single antenna or multiple antennas of direction finding (DF) antenna array and associated electronics without interference of external signals such as ground interference signals present when an aircraft-based antenna is tested on the ground. An individual antenna test enclosure may in one embodiment be provided as an antenna hood having a cavity dimensioned for internally receiving an antenna, such as an aircraft external blade antenna. The cavity of the antenna enclosure may be lined with a RF absorbing material inside the enclosure to allow for RF path testing with substantially no “ringing”, so that accurate phase and gain testing of a received antenna and its RF signal path may be accomplished.

Abstract: An apparatus for measuring a radiation pattern of an active antenna arrangement is provided, where the active antenna arrangement includes one or more radios having dedicated antenna elements in communication with each other. The apparatus has a common module external to the active antenna arrangement and a calibration radio, which is also external to the active antenna arrangement and coupled to the common module. The common module includes a transmit/receive unit and interfacing means for interfacing the common module with the active antenna arrangement, with the calibration radio and with a network node. The common module further includes a measurement device for measuring signals received from the active antenna arrangement.

Abstract: An adaptor with a lower portion designed to be connectable to an upper horizontal opening serving as electromagnetic aperture of a reflector frame of a surface-mountable antenna device and an upper portion of the adaptor being designed to accommodate a waveguide of testing or tuning equipment.

Abstract: A method is provided for estimating the focusing quality of a signal pre-equalized by time reversal of an estimated propagation channel between a source antenna of a source communicating entity and a destination antenna of a destination communicating entity, the method comprising a step of evaluating a focusing quality of the signal received at the destination antenna relative to a value at a focal point of a representation of a curve of received power as a function of a distance between the destination antenna and the focal point.

Abstract: A sensor for measuring electromagnetic power in a dielectric waveguide structure includes an antenna element for detecting heating caused by electromagnetic power absorbed into the antenna element. A membrane forming at least partially a thermally insulating layer is implemented on a surface of the dielectric waveguide structure being a substrate for the sensor. The antenna element is implemented on a surface of the membrane and the antenna element is at least partially thermally insulated with a cavity from the substrate. A method for fabricating the sensor is also described.

Abstract: A measurement apparatus includes an anechoic chamber, a DUT board, rotation units, and a feeding arm. The anechoic chamber has inner-walls. Each inner-wall is covered with a radio wave absorber. One of the inner-wall is a first wall with an aperture and the other inner-walls are second walls. The DUT board holds a first antenna to be measured with radiation property and a probe to detect a signal from the first antenna. A part of the DUT board is inserted into the anechoic chamber through the aperture opened in the first wall. One end of the feeding arm holds a second antenna radiating a radio wave to the first antenna in the anechoic chamber. Each rotation unit provides on each second wall and is selectively attached to the other end of the feeding arm for rotating the second antenna and for feeding to the second antenna.

Abstract: The present invention provides a radio field intensity measurement device having a display portion with improved visibility, in the case of measuring a weak radiowave from a long distance. In the radio field intensity measurement device, a battery is provided as a power source for power supply and the battery is charged by a received radiowave. When a potential of a signal obtained from the received radiowave is higher than an output potential of the battery, the power is stored in the battery. On the other hand, when the potential of the signal obtained from the received radiowave is lower than the output potential of the battery, power produced by the battery is used as power to drive the radio field intensity measurement device. As an element to display the radio field intensity, a thermochromic element or an electrochromic element is used.

Abstract: The invention concerns a system for simulating electromagnetic environments, including a network of emitting and/or receiving probes to test at least one test antenna, channels for connecting the probes to a channel emulator, a signal emitting unit, a signal receiving unit, one of the units being connected to the emulator. The invention is characterized by a switching device having a first measurement position, in which the device connects the emulator respectively to at least one of the probes via the associated channel and connects the other unit to the test antenna, and a second position for calibrating the channels, in which the switching device connects the emulator to the other unit via the associated channel without passing through the network of probes.

Abstract: A camera based positioner (CBP) for near-field measurement and a method therefor, and a near-field measurement system are provided. A measurement probe and an antenna under test (AUT) are automatically aligned to a position for near-field antenna measurement by recognizing a position and a rotation angle of the AUT based on an interval and an angle between neighboring laser sources represented in an image taken by emitting laser beams from at least two laser sources located with a predetermined interval and a predetermined angle.

Abstract: An antenna for electromagnetic compatibility testing, that includes an upper plate and a lower plate having parallel longitudinal axes, maintained at a distance from each other, and mechanically connected to each other at each of their longitudinal ends by longitudinal plates. The upper and lower plates and longitudinal plates define a space. The upper and lower plates and the longitudinal plates are mounted so as to be capable of movement relative to each other to define a space having dimensions that can be modified, wherein the distance between the lower and upper plates can be modified and/or the length of the lower and upper plates can be modified.

Abstract: A method for measuring a radiation field in the direct vicinity of a measured object is provided. One or more antenna measurement probe(s) are moved in any desired fashion within the radiation field, and a number of high-frequency measurement points is thus recorded. During the movement of the antenna measurement probe, a position determination of a respective antenna measurement probe is conducted simultaneously with or in close temporal proximity to the capture of a respective high-frequency measurement point, in order to assign a position to each high-frequency measurement point so as to generate a spatially defined measurement point cloud. Finally, radiation patterns at any distance from the measured object may be determined from the spatial measurement point cloud by means of a field transformation method.

Abstract: A system and method for testing RF characteristics of a wireless device. The wireless device is placed on a base plate of a test fixture. One or more guides are positioned for securing the wireless device. At least one RF antenna is positioned. The position of the wireless device and the at least one RF antenna coupler relative to each other corresponds to acceptable RF characteristics for testing the wireless device. Positions of the one or more guides and the RF antenna coupler are identified. The identified positions are utilized to subsequently test similar wireless devices.

Abstract: An antenna evaluation apparatus includes receiving antennas to be evaluated, scatterer antennas surrounding the receiving antennas, a signal generator, a divider, a phase-shift circuit, and a computer. The computer generates first and second initial phase vectors each corresponding to a different set of multipath waves, determines a third initial phase vector including arbitrary initial phases each between a pair of corresponding initial phases in the first and second initial phase vectors, adjusts the phases of the radio frequency signals using the phase-shift circuit such that the phases of the radio frequency signals have corresponding initial phases in the third initial phase vector, and makes the adjusted radio frequency signals radiate.

Abstract: A target antenna 4A to be measured and a measuring antenna 5 are placed within an anechoic chamber 1. A first azimuth angle plane radiation pattern S21(R,?,?) is measured using a network analyzer 7 with an elevation angle ? of the target antenna 4A fixed to a first angle ?1. Next, a second azimuth angle plane radiation pattern S21(R,?,?) is measured using the network analyzer 7 with the elevation angle ? of the target antenna 4A fixed to a second angle ?2 different from the first angle ?1 by 90 degrees. A radiation efficiency of the target antenna 4A is measured by integrating in a spherical shape the azimuth angle plane radiation patterns S21(R,?,?) at two planes.

Abstract: Methods and apparatus for determining parameters for an array are described. An exemplary embodiment of a method determines a set of parameters for an antenna array including multiple array elements, the array being fed by a feed array including a plurality of feed elements. The embodiment of the method includes measuring a plurality of bistatic ranges Rijk through different signal path combinations, each signal path combination from a feed element “i,” to an array element “j,” and to a feed element “k”. The measuring includes radiating energy from feed element “i”, and reflecting some of the radiated energy from array element “j” back to feed element k of the feed array. The measured bistatic ranges are processed to solve for the set of parameters.

Abstract: A method for determining the minimum measurement distance of an antenna of a wireless mobile terminal, comprising the following steps: establishing a test environment of an antenna of a wireless mobile terminal to be tested; determining electromagnetic scattering dimension of the antenna of the wireless mobile terminal to be tested and an electromagnetic scattering body in a predetermined spatial area in the test environment; and calculating the minimum measurement distance of the antenna of the wireless mobile terminal according to the determined electromagnetic scattering dimension. Electromagnetic scattering dimension of the mobile phone antenna and the electromagnetic scattering body in the predetermined spatial area is determined and measured in a simulated network environment in an electric wave anechoic chamber, and parameters of the minimum measurement distance of the mobile phone antenna can be calculated and obtained.

Abstract: An antenna testing device includes an analyzer, a transmission probe electrically connected to the analyzer, a receiving probe electrically connected to the analyzer, and a shielded box having a cutoff frequency. The analyzer generates a test signal the frequency of which is lower than the cutoff frequency, the transmission probe receive the test signal and sends the test signal to the shielded box. The antenna is coupled with the transmission probe and generates a coupled signal, the receiving probe receives the coupled signal and sends the coupled signal to the analyzer. The analyzer analyzes the coupled signal and the test signal, the analyzer calculates the return loss of the antenna.

Abstract: Electronic device structures may be tested using a radio-frequency test system. The radio-frequency test system may include radio-frequency test equipment and an associated test fixture. The radio-frequency test equipment may be used in generating and measuring radio-frequency signals. The test fixture may contain adjustable structures that allow the positions of radio-frequency test probes to be adjusted. The test system may be configured to position radio-frequency probes in the test fixture so that some probe contacts form electrical connections with conductive antenna structures. The radio-frequency probes may contain other contacts that are positioned to form electrical connections with conductive electronic device housing structures. During radio-frequency testing, the test equipment in the test system may apply radio-frequency test signals to the device structures under test using the test probes. Corresponding radio-frequency test signals may be measured by the test equipment.

Abstract: An apparatus for measuring radiated power of a terminal includes: an enclosure including a pair of couplers configured to couple an electromagnetic field radiated from the terminal or a substitution antenna and a measurement jig configured to rotate the terminal or the substitution antenna, the terminal or the substitution antenna being supposed to be arranged between the pair of couplers, with reference to at least one of X, Y, and Z axes; a driver installed outside the enclosure to drive the measurement jig; a signal generator configured to generate a feed signal transferred to the substitution antenna when the substitution antenna is arranged on the measurement jig; a feed signal transmitter configured to transfer the feed signal generated by the signal generator to the substitution antenna; and a spectrum analyzer configured to measure power of a radiated signal radiated from the terminal or the substitution antenna.

Abstract: The present invention discloses a method and system for testing OTA performance in a multi-antenna system. Multiple antennas are set in an anechoic chamber; a BS simulator is controlled to transmit benchmark test signal to DUT through a channel emulator and antennas; when determining the benchmark test signal does not meet set requirement, the benchmark test signal is adjusted until set requirement is met; corresponding test cases are determined according to different channel models; according to channel models, the channel emulator performs channel simulation processing on test signal output from the BS simulator and sends the test signal to DUT through antennas; after DUT receives the test signal, each OTA performance is tested according to OTA performance test items corresponding to test cases; and DUT is judged to reach the standard when all OTA performances reach the standard. The present invention is easy to implement and has a low cost.

Abstract: In an automatic tuning system for a loop antenna having a single electronically variable reactance element, the reactive component sense of the antenna impedance is determined over a wide range of frequency. The electronically variable reactance component of the antenna is automatically minimized by a feedback loop driving a voltage variable capacitance until the reactive component of the antenna impedance is virtually zero and the antenna impedance is hence resistive. The adjustment of the electronically variable capacitance is by a variable high voltage power supply controlled by a feedback amplifier or by a high voltage feedback amplifier.

Abstract: Devices, systems, and methods are disclosed which relate to verifying an antenna via a transmitter. A logical interface coupled to a transmitter reads antenna specifications from a memory integrated with an antenna, and refuses transmission when the antenna attributes conflict with the requirements of the transmitter.

Abstract: The present invention, as typically embodied, implements an energy source, a transmitting antenna, a receiving antenna, a resonant cavity, and an electricity meter (e.g., voltmeter, ammeter, or power meter) to calibrate an electronic device. Firstly, the receiving antenna is calibrated based on measurement of power that has been generated and transmitted in known quantity, propagated through air, and received by the receiving antenna. Secondly, the resonant cavity is connectively situated between the transmitting antenna and the receiving antenna; the resonant cavity is calibrated based on measurement of power that has been generated and transmitted in the same quantity, propagated through the resonant cavity, and received by the receiving antenna.

Abstract: An electromagnetic radiation measuring device includes a test antenna module and a main processor electrically connected to the test antenna module. The test antenna module includes a plurality of pre-test antennas and at least one final test antenna, which have predetermined polarities and are positioned at predetermined heights, respectively. The pre-test antennas and the final test antenna respectively receive wireless signals sent from an electronic device. The main processor measures and records a frequency of the strongest wireless signal received by selected ones of the pre-test antennas that have the same polarity, and further determines whether power of wireless signals at the recorded frequency received by the final test antenna polarized to have the same polarity as that of the selected ones of the pre-test antennas exceeds a predetermined acceptable range.

Abstract: There is disclosed an apparatus for measuring the strength of an electromagnetic field. The apparatus comprises a plurality of antennas arranged such that the field is received from all directions, each antenna supplying an RF signal as output. The apparatus also comprises a plurality of transforming modules, each of said modules being fed with the RF signal supplied by one of the antennas, each of said modules transforming the impedance of the RF signal it receives as input, so as to supply another RF signal as output. The apparatus also comprises a plurality of converting modules, each of said modules being fed with the RF signal supplied by one of the transforming modules, each of said modules converting the RF signal it receives as input into a DC current it supplies as output, said DC current varying substantially as a logarithmic function of the said RF signal.