41 results about "Antenna input impedance" patented technology

Real-time calibration of a tunable matching network that matches the dynamic impedance of an antenna in a radio frequency transmitter system. The radio frequency transmitter system includes two non-linear equations that may be solved to determine the reflection coefficient of the antenna. The tunable matching network is repeatedly perturbed and the power reflected by the antenna is measured after each perturbation at the same node within the tunable matching network. The power values are used by an optimizer in converging to a solution that provides input impedance of the antenna. The elements of the matching circuit are adjusted to match the input impedance of the antenna.

Antenna apparatus, and an associated methodology, for a multi-frequency-band-capable radio device, such as a quad-band mobile station. The antenna apparatus is formed from a three-dimensional rectilinear non-conductive dielectric antenna substrate, such as cube. An elongated radiation element is disposed over multiple surfaces of the antenna substrate. A T-shaped impedance matching element located at the end of the radiation element permits the antenna input impedance to be matched to a communications device. The length of the radiation element is selected to be substantially equal to a quarter wavelength of the lowest frequency band at which the antenna operates.

A spiral antenna having a pair of antenna arms mounted on a dielectric substrate. A balun is included to connect the antenna which has an impedance of 100 ohms to a 50 ohm cable. Unique features of the spiral antenna design provide for size reduction at a given lowest required frequency of operation. The spiral antenna has dielectric material layers positioned on both side of the antenna's metal arms. In addition, the antenna input impedance is reduced from the normal 100 ohm input impedance to approximately 50 ohms due the dielectric material.

1. A device and a method for the improved directional estimation and decoding by means of secondary radar signals. 2.1 Radio-based positioning systems on the basis of secondary radar signals are known. For this purpose special receiver systems are utilized for estimating the direction, and special receiver systems are utilized for decoding secondary radar signals. In particular, a secondary radar system is absent, which, among others, takes into consideration any shortcomings of the hardware used, such as coupled antenna elements, different low-end impedances, deviating distances between the antenna elements, manufacturing and installation tolerances, and the like. 2.2 The device for directional estimation and / or decoding secondary radar signals according to the invention comprises the following: - at least one array A comprising M antenna elements AE - an amplifier LNA and bandpass filter F 1 combination connected to a plug-in connector S of the respective antenna element AE, at the filter output of said combination a first linear amplifier V 1 being connected for amplifying the band-limited signal, - a mixer M connected to the first linear amplifier V l for the frequency conversion into a ZF region, - a second linear amplifier V2 and bandpass filter F2 combination connected to the mixer output for amplifying and limiting the bandwidth of the signal in the ZF region, - a first analog-to-digital converter AD1 connected to the second bandpass filter F2 for scanning and quantifying the filter output signal. 2.3 The invention is within the field of secondary radar systems.

A dielectric loaded sleeve monopole antenna has a dielectric loading within the sleeve enables stable impedance in a dynamic operating environment. The use of a dielectric filling in the sleeve portion of the antenna enables tight control of the input impedance over frequency establishing stable broadband operation in challenging operating environments. The effective dielectric constant inside the sleeve of the antenna is designed to exhibit spatial variability. As a result, the sleeve essentially acts as an impedance transformer enhancing control over the input impedance to the antenna. The spatial variability in the dielectric filling may be realized as arrangements of single or multiple dielectric materials machined to synthesize the desired effective dielectric properties. The antenna may also include the addition of filtering elements inserted into the sleeve to reduce interference for multi-band wireless communication systems.

The invention discloses a method for measuring antenna impedance on an ultrahigh frequency radio frequency identification electronic tag. The method mainly solves the problem of influence on measurement precision caused by precision of an impedance measurement device. The method comprises the implement steps of first, calibrating a vector network analyzer for measurement through an electronic calibration part; second, connecting the port of the vector network analyzer with a single-end SMA connector of a difference balun clamp through a measurement line; third, sequentially measuring input impedance values of the difference end of the difference balun clamp under the states of short circuit, open circuit and connection with 50-ohm resistance; fourth, measuring the input impedance value of the single-end SMA connector under the state that the difference end of the difference balun clamp is connected with a balancing antenna to be measured; fifth, performing calculation according to the above four measured parameters to obtain the input impedance of the radio frequency identification balancing antenna. By means of the method, the influence on the measurement result caused by precision of the measurement device is avoided. The method has the advantages of being simple and quick in operation and high in measurement precision and can be suitable for measuring the input impedance of the balancing antenna on the ultrahigh frequency radio frequency identification electronic tag in a large-batch mode.

The invention relates to a broadband phased array antenna unit and a radiation method thereof. The external radio frequency signal is fed into the broadband phased array antenna unit through a feedingcoaxial connector, and the fed external radio frequency signal forms two different current distributions on the cooperation of a ring radiator and a ring radiator, a matching branch and an additionalresonant branch respectively; the external radio frequency signal is fed into the broadband phased array antenna unit through a feeding coaxial connector. The current on the annular radiator resonates at high frequencies of the operating frequency, The loop radiator, the matching branch and the additional resonant branch form the resonant current at the low frequency, the two resonant points effectively increase the bandwidth of the antenna element, and the electromagnetic waves generated by the two resonant points are radiated into the free space by the wideband phased array antenna element;the loop radiator, the matching branch and the additional resonant branch form the resonant current at the low frequency. The impedance matching of wideband phased array antenna elements is realizedby changing the input impedance of wideband phased array antenna with matching branch and loop radiator. The invention can be widely applied to phased array antennas of mobile platforms such as satellite-borne, airborne, missile-borne and ground-based terminals.

The invention provides a multi-band antenna and a mobile terminal. The multi-band antenna comprises an antenna body, matching circuits and a frequency demultiplexer, wherein each matching circuit comprises multiple matching subcircuits, one end of each matching subcircuit is connected with a ground wire feeding point or a signal feeding point of the antenna body, the other end of each matching subcircuit is respectively connected with input interfaces for corresponding frequency bands of the frequency demultiplexer, and the matching circuit is used for modulating antenna input impedance of the antenna body during operation in a corresponding frequency band; and the frequency demultiplexer is used for separating signals which are received or transmitted by the antenna body and at different frequencies. The multi-band antenna provided by the embodiments of the invention has the advantages that the frequency demultiplexer is arranged in the multi-band antenna and separates the signals which are received or transmitted by the antenna and at different frequencies, so that the signals at different frequencies pass through different matching circuits, the input impedance of the antenna is modulated, the antenna works in different frequency bands at the same time, and requirements of CA on multiple frequency bands and multiple combinations are met.

A system for remotely measuring antenna input impedance utilizing an automatic antenna tuner in which, for any tuner, the tuner input impedance may be established by the values of the components in the circuit at the time that the SWR is at a minimum, with these values being automatically available in terms of the components that are switched in to achieve low SWR. Once having established the input impedance to the tuner, the complex conjugate of the tuner input impedance yields the antenna input impedance, with antenna input impedance sensed at full power at a position remote from the antenna input.

The invention relates to a test system for accurately measuring dielectric constants. The test system comprises an antenna part, a radio-frequency circuit part and a data processing and displaying part. The antenna part comprises a testing antenna and a scattering sample, the radio-frequency circuit part comprises a radio-frequency signal source and a radio-frequency circuit, and the radio-frequency circuit is composed of a directional coupler, a low noise amplifier, a power divider, a mixer and a low pass filter. The data processing and displaying part is composed of an amplifying circuit and an ARM development board. Electromagnetic parameters of the sample are accurately measured with changes of the input impedance of an antenna and a radiation field. The test system has the advantages that low dielectric constant materials and high dielectric constant materials can be accurately measured, errors are small, the testing system is simple, integration is convenient to achieve, the scattering sample is simple in shape and easy to machine, and sweep testing can be carried out on the scattering sample.

The invention discloses a radio frequency transmitting circuit, comprising a radio frequency transmitter, an antenna switch and an antenna. A bidirectional coupler and an antenna tuner are arranged between the antenna switch and the antenna. The bidirectional coupler comprises a directional coupler and a switch, and forward or reverse transmission power is detected by switching the switch. The directional coupler is provided with a plurality of connected coupling lines, which are respectively located at any one or more positions of the upper side, the lower side, the outer side and the inner side of a main signal line. The bidirectional coupler is both used for detecting the transmitting power and is used for detecting the reflected power and outputting a detection value to the radio frequency transmitter. The radio frequency transmitter is both used for calibrating the transmitting power and is used for adjusting the input impedance of the antenna to realize the impedance matching of the antenna. The invention further discloses a bidirectional coupler, which has the advantages of simple structure, small volume, low cost, and easy integration with the manufacturing process of integrated circuits. The invention further discloses a directional coupler, which has high coupling degree and low insertion loss.