The paper presents an analysis of a microwave interferometer with a multi-ports architecture with one input and four outputs. The tested system consisted of two main parts: a subsystem consisting of a power divider and two transmission lines of different electric length - responsible for developing two signals whose phase difference will depend on the frequency of the input signal. The second part of the tested system consisted of a six-port element - a 4 x 4 Butler matrix, whose task was to develop four signals. The output amplitude depends on the phase difference of the signals fed to the inputs of this six-ports. Frequency detector tests were carried out by calculations in the MATLAB computer program in a very wide band fg/fd=4. The system response was analyzed for different combinations pair of an input ports of a six-port system and for different values of coupler coupling coefficients. During the analysis it was shown that the parameters of such an interferometer depend on which ports pair is excited as well as on the value of the coupling factor of the couplers. It is important to specify the system parameters in order to make the optimal selection of the interferometer system configuration in terms of the acceptable frequency detection error, operating bandwidth, or even the topological distribution of the ports.
Single-function microwave frequency detectors are used in the structures of multichannel frequency discriminators. They allow determining the frequency of an unknown signal in a very short time of the order of hundreds of nanoseconds. The shape of the output voltage of the single-function detector versus frequency is described with a cosine or a sine function. In the systems, where a great accuracy of frequency determination is not required, and a time measurement is vital, it is possible to apply only one single-function frequency detector. A single-function frequency detector is composed of two blocks: a system of developing of proportional phase difference and a phase sensitive detector. The function of the first block is to generate two output microwave signals with a phase difference between them proportional to the frequency of the input signal. A phase sensitive detector converts the difference of phases of input signals into voltage. The output voltage is subject to further processing and, based on it, the frequency of the input signal is determined.
A principle of quadrature correlation detection of noise signals using an analog broadband microwave correlator is
presented in the paper. Measurement results for the correlation function of noise signals are shown and application of
such solution in the noise radar for precise determination of distance changes and velocity of these changes is also
presented. Results for short range noise radar operation are presented both for static and moving objects. Experimental
results using 2,6 - 3,6 GHz noise like waveform for the signal from a breathing human is presented. Conclusions and
future plans for applications of presented detection technique in broadband noise radars bring the paper to an end.
Conference Committee Involvement (1)
XII Conference on Reconnaissance and Electronic Warfare Systems
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