B. Huyart

Five-port junction: In the way of general public applications

The replacement of a six-port reflectometer by a five-port interferometer junction in general applications is presented. This simplification provides a considerable reduction in the time processing usually required by six-port based systems. It is also shown that the five-port system is suitable to general applications without performance degradation when compared to six-port based systems.

Power amplifier characterization: an active load-pull system based on six-port reflectometer using complex modulated carrier

An original measurement system for nonlinear RF power-transistor characterization is presented. This new setup enables measurement and optimization of output power, power-added efficiency (PAE), or linearity using active fundamental tuning and six-port reflectometers as vector network analyzers. High- and low-frequency bias-tees are inserted at both ports of transistors in order to control source and load impedances at the baseband (envelope) frequency. Experimental results at 1.575 GHz show an adjacent channel power ratio improvement of 20 dB for a commercial GaAs MESFET power transistor operating in class AB. Moreover, the output power and PAE are increased by 1 dB and ten points, respectively

Microwave Measurement using Wheatstone's Bridges

This paper presents the design of Monolithic Six-Port Module MSPM with resistive bridges. It shows how these simple structures may act as directional resistive couplers. Final MMIC circuit includes six-port junction and matched MESFET detectors covering an area of 1.2 mm2 in the frequency range 100 MHz to 3 GHz. The MSPM was bonded in a MIC structure with output coaxial connectors or inside the tips of a probe station. In this last case, the MSPM acts as an active probe. Experimental results obtained using a commercial network analyzer and our measurement system are in good agreement.

A new structure for a six-port reflectometer using a silicon MOSFET for power measurement

This paper presents a new structure for silicon MMIC sixport reflectometer. Its originality lies in the use of a newly developed power detector using a silicon MOSFET transistor as an alternative to the commonly used biased Schottky diode detector. The power detector using a nonbiased MOSFET transistor has demonstrated a better sensitivity than the Schottky diode detector counterpart. The six-port reflectometer calibration uses minimum of five loads with an unknown but constant absolute value of the reflection coefficient and unknown but well-distributed phases. The circuit has been fabricated in silicon MMIC technology working between 0.9-3.0 GHz. A thorough comparison of the measured data with a commercial network analyzer is presented.

A source-pull/load-pull measurement system including power amplifier linearization using simple instantaneous memoryless polynomial base-band predistortion

In this paper, an original measurement system for non-linear power characterization is presented. This set-up enables optimization of output power or power added efficiency (PAE) in conjunction with transistors linearization. The optimization of the fundamental impedances is performed using source-pull/load-pull measurements before a base-band predistortion is carried out. The linearization method for complex modulated carrier is based on the measurement of the instantaneous AM/AM characteristic and on the measurement of the AM/PM conversion. Therefore, an instantaneous memoryless polynomial base-band predistortion is obtained. Experimental results at 1.575 GHz for a commercial GaAs MESFET transistor biased in class AB show improvements equal to 15 dB and 5 dB for the C/I3 and ACPR values, respectively

Measurement of Direction of Arrival for Radar Application

This paper presents theoretical and experimental results of a RF direct technique to determine the directions of arrival (DOA) of multiple radio frequency (RF) signals from an array of antennas with an array of six-port reflectometers (SPR). The DOAs will be used for tracking multiple targets in a duplex radar system at 2GHz. This simple and original receiver system, allows to determine the directions of arrival of differents signals, detected from different targets with only 4 samples.

A Novel Method for Direction of Departure Estimation Using a Linear Frequency Modulated Signal

A novel method for the Direction of Departure (DoD) estimation with a parallel transmitter array is presented. It requires the use of a signal which frequency increases linearly in time, regardless of whether this variation is discrete or continuous in time. Due to the properties of these signals, adding different delays to the signals transmitted by each of the antennas enables to separate them at the receiver. The advantages of this novel method are fast real-time measurements, simplicity and low hardware cost. Once separated, the signals can be treated with a high-resolution algorithm to estimate the DoD. In order to validate the capability of this method, simulation results and preliminary real measurements are presented.

A to D converters and look-up tables dimensioning for five-port reflectometer based systems

A M Thefive-porf repectometer hos been recently npplied lo demodulators and radars, allowing the trnmfer of analog circuit eomplexio to digit01 sipdpmcessimg. I n order lo operate in real-time mode, these systems demand optimized DSP olgorithms. One technique we hove been erploiling consists on using look-up tables 11, estlmole normolized power values from voltoges measwed at the repectometeer’s outputs. We evoluvte in this papar the errors incorporated by voltages mdlook-up table qumtizirotion. Comporbons bemeen diflerent combinations o/A/Df resolution m d LUT’s word size are done using measurement wIue3.

Low cost network analyzer using a six-port reflectometer

This paper presents a simple system for measurement of complex ratio between two RF signals that can be applied to measurement of reflection coefficient of a network port or exhibit the constellation diagram of phase-modulated signals. The system is based on a six-port reflectometer and digital signal processing.

New structure for a six-port reflectometer in MMIC technology

This paper presents a new structure for a six-port reflectometer which due to its simplicity can be integrated very easily in MMIC technology. It uses non-matched diode detectors with a high input impedance that are placed around a phase shifter. The circuit has been fabricated by the foundry GEC-Marconi and operates between 1.4 and 2.5 GHz.