Wolfram Schilz

Remote Temperature Sensing in Organic Tissue by Ferrimagnetic Resonance Frequency Measurements

A remote temperature sensing method is presented which uses the temparature dependence of the ferrimagnetic resonance frequency in iron garnet spheres. The garnet material parameters are discussed for optimizing the measuring sensitivity and the temperature resolution. An accuracy of 0.3°C in the range of 35 to 50°C has been achieved.

A modulated subcarrier technique with instantaneous amplitude and phase information

An accurate and instantaneous microwave phase and amplitude measurement technique is described, that makes use of a single-sideband generator and a single-sideband detector. The phase and amplitude values of a microwave signal are transposed to an IF signal of a convenient frequency. The dynamic range may be as high as 80 dB and the phase and amplitude errors in this range are below 1° and 0.1 dB, respectively.

High Frequency Dielectric Data on Selected Moist Materials

AbstractThis paper presents data on the complex dielectric constant of various industrially important materials as a function of moisture, temperature, and frequency.

Microwave Distance Meter with ± 2.5 mm Resolution

A range resolution of ± 2.5 mm has been obtained with a FMCW radar and a sophisticated signal processing. The system operates at X-band with 1.5 GHz frequency sweep. It makes use of the fact, that the total phase length ¿¿ of the IF waveform produced by superposition of the transmitted and reflected FMCW signal is an exact measure of the distance, if reflections of only one target are present. The measurement of the total phase length is performed by counting the zeros of m subsequent IF pulses, while the start phase of each pulse is changed in steps of 2/¿m. This procedure results in an accuracy of the ¿¿ measurement ¿ 2¿/m. The signal processing is realized by a combination of a single-sideband mixer and a low frequency modulator followed by digital electronics.

Novel Microwave Technique for Industrial Measurements

Based on traditional microwave techniques a new branch is rapidly growing: The application of microwaves for industrial measurements and process control. In many cases microwaves are superior to other methods because of the specific microwave behaviour of materials and the possibility of contact-free, remote probing. The use of microwave techniques has been stimulated by the development of integration techniques both for the microwave part and the signal processing part which allows the construction of compact instruments. This paper includes a general report on the various applications of microwaves in industrial measurement and a discussion of the technical aspects. Some applications of this technique in medical diagnostic will also be mentioned.

A Microwave Spectrometer - Suitable for Gas Analysis in Industrial Applications

A compact spectrometer has been developed, operating between 18 and 26 GHz, suitable for industrial gas analysis in process and pollution control. The system is all solid state and may operate automatically. Care has been taken to minimize the system noise figure, among others with a novel balanced arrangement of two absorption cells operating in parallel. Measurement results with different gases and gas mixtures and details of the system are reported.

Broadband Matching of Microstrip Differential Phase Shifters

Meanderline phase shifters in microstrip are badly matched (vswr ¿ 2), due to the difference in phase velocity of the odd and even mode of the coupled transmission lines. This is overcome by a stepped impedance design, allowing to realize e.g. a 90° phase shifter with a return loss better than 30 db across an octave bandwidth. Straightforward design equations are derived and confirmed by measurements on MICs in the frequency range 4 to 8 GHz and X-band.

A Measuring System for the Industrial Application of Microwave Spectroscopy

AbstractA compact all solid-state microwave spectrometer has been built, operating between 18 - 26 GHz. The instrument can be used for the quantitative analysis of gas mixtures. The system has been optimized with respect to sensitivity and noise and a number of measurements on gases and gas mixtures are described.