Applications of the Microwave Vector Network Analyzer (MVNA)

The Vector Analyzer MVNA can be used for various kinds of measurements, both, for the classical type microwave engineering circuits characterization, and also for many novel applications in research and industry. Some of these applications are listed below, and the users of MVNA worldwide have invented and developed many more.

Antenna characterization

Antenna measurements need a microwave bench including a source, and a detector. Vector measurements are important since they determine directly the phase center and curvature. They also allow the time domain analysis, after Fourier Transform of the vector signal. MVNA-8-350 offers a broad band microwave source and a vector detection with a very large dynamic range. Its millimeter heads are very compact, and flexible connecting cables, up to 10 m long, are sufficient for most of the millimeter antenna bases. For these reasons MVNA-8-350 is extremely well adapted to antenna characterization. See also the publication in Microwave Journal, p.98, June 1994, Ref.(1), and Refs. (2, 3).

Quasi-Optics Transmission-Reflection and Radar modeling

Millimeter-submillimeter waves belong to the electromagnetic waves spectrum. They are located between microwaves, which can be propagated into coax cables or waveguides, and light (infrared or visible), which propagates mostly in free space. Millimeter-submillimeter waves can be propagated into waveguides. However, waveguides are more and more lossy and difficult to machine at growing frequencies, since the wavelength becomes too small: for instance the width of a TE01 waveguide of the order of the wavelength, is about 3 mm at 100 GHz, and only 0.3 mm at 1000 GHz. Millimeter and especially submillimeter waves can be propagated into free space. In this case the optical components like lenses, mirrors, etc., have dimensions which cannot be viewed as very much larger than the wavelength, contrary to light propagation. Because of that, care must be taken of diffraction problems, and the technique is called quasi-optics rather than optics. See the paper "Quasi-Optics Vector Transmission-Reflection from 18 to 760 GHz", Ref. (4), and Refs. (5-6).
Its good dynamic range, and its frequency flexibility, make the MVNA-8-350 an ideal tool for radar modeling experiments, offering, with ASA-1 and ASA-2 standard extensions, approximately 130, 125, and 100 dB at 300, 400, and 500 GHz respectively.

Material Characterization without and with Magnetic Fields

Because of its unique capabilities, MVNA becomes a useful tool in many areas of solid state research in the important but until recently only partially explored spectral range. The 8-1000 GHz frequency domain covered by the MVNA-8-350 bridges the interval between ordinary microwaves and infrared techniques. Replacing older, expensive, short-living and exotic sources of radiation in the millimeter and submillimeter range, MVNA provides easy and reliable access to study various problems in the whole spectral range below 1 terahertz. In particular:

In units of wavelength, the corresponding MVNA wavelength coverage is 37-0.3 mm. Mechanical structures with periodic length, or aperiodic, controlled shape (Sinai billiard-like structures) are easily machined in that size range, for instance to create and study photonic band-gap crystals, and deterministic chaos structures. A microwave microscope imaging with resolution better than a fraction of the wavelength has been demonstrated recently opening new possibilities for submillimeter wavelengths micro-imaging.
In energy units, the MVNA covers the range 0.03 - 4 meV (equivalent to 0.27-33 cm^-1). This range contains characteristic energies of many elementary excitations in solids, including optical and acoustic magnons in magnetically ordered systems, gaps in spin and charge density wave crystals, soft phonons in ferroelectrics, superconducting gaps, molecular rotational excitations, etc.
The broad spectral range of MVNA, covering over two decades of energies, makes it an ideal tool for broad band studies of dielectric relaxation in solid and liquids.
With superconducting magnets generating magnetic fields up to 20 Tesla becoming ubiquitous in laboratories, there is growing interest in high field studies of electron spin resonance, cyclotron resonance and of related phenomena, see Ref. (7). For a cyclotron mass equal to the free electron mass, or for free electron spin resonance, at 20 Tesla the resonance frequency is 560 GHz, almost in the middle of MVNA spectral range.
The millimeter heads of the MVNA-8-350 are small and light (about 7 cm long, 100 g for HG and HM). Since they are linked to the Analyzer main body through flexible coax cables, which can be extended to 10 m, the microwave set-up can be attached to almost any, even difficult to access, equipment like big cryostats, dilution refrigerators, etc.

According to considerations above, MVNA-8-350 is a very useful tool, sometimes without competitor, to characterize materials without and with magnetic fields.

Waveguide and Cavities setups

The vector Analyzer MVNA-8-350 is well adapted to measurements of waveguide setups, see Ref. (7). The phase information obtained by transmission is a direct and accurate measurement of the "optical" length of any propagating device. A reflection measurement is obtained thanks to a directional coupler. Then, the propagation mismatch positions are characterized by using the Fourier Transform capabilities of the installed software.
Cavities measurements have been the first applications of the MVNA-8-350, see Ref.(7). The installed software permits very precise fits of these Lorentzian resonances.
At Ecole Normale Supérieure, Laboratoire Kastler-Brossel, Paris, (S. Haroche, J-M Raimond, M. Brune), cylindrical, and Fabry-Perot tunable cavities made of superconductive niobium (Nb) have been studied with MVNA with Q factors as large as 10⁹. These cavities have been used for fundamental quantum mechanics studies of interaction of microwave photons with excited atoms (Rydberg atoms). Recently, that research was recognized with CNRS year 2009 Gold Medal awarded to professor Serge Haroche.

References

For the complete reference list see also Section V of Products. Reprints are available upon request from AB Millimetre.

"Antenna vector characterization in the mm- and submm-wave regions", P. Goy, Microwave Journal, June 1994, p.98.
"Vector transceiver for millimeter wave antennas", P. Goy, M. Gross, 20^th ESTEC - European Space Agency Antenna Workshop on Millimeter Wave Antenna Technology and Measurements, 18-20 June, 1997, Noordwijk, The Netherlands.
"Millimeter and submillimeter wave vector measurements with a network analyzer up to 1000 GHz. Basic principles and applications." P. Goy, M. Gross, S. Caroopen, 4^th Int. Conf. on Millimeter and Submillimeter Waves and Applications, July 20-23 1998, San Diego, CA, USA.
"Quasi-optics vector transmission-reflection from 18 to 760 GHz", P. Goy, M. Gross, Workshop on low-noise quasi-optics, 12-13 September, 1994, Bonn, Germany.
"Free Space Vector Transmission-Reflection from 18 GHz to 760 GHz", P. Goy, M. Gross, 24^th European Microwave Conference, 5-8 September 1994, Cannes, France.
"Millimeter-submillimeter measurements in free space, and in resonant structures. Application to dielectrics characterization." P. Goy, M. Gross, S. Caroopen, J. Mallat, J. Tuovinen, A. Maestrini, G. Annino, M. Fittipaldi, M. Martinelli, Material Research Society Spring Meeting, April 24-28 2000, Symposium AA "Millimeter-submillimeter wave technology, materials, devices, and diagnostics", invited talk, San Francisco, USA.
"Magnetooptical millimeter wave spectroscopy", C. Dahl, P. Goy, J.P. Kotthaus, in "Millimeter and Submillimeter Wave Spectroscopy of Solids", ed. G. Gruener, Springer-Verlag Berlin Heidelberg , 1998, ISBN 3-540-62860-6, pp. 221-282.

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