The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
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Applications of Hologram-Based Compact Range: Antenna Radiation Pattern, Radar Cross Section, and Absorber Reflectivity Measurements

Anne Lönnqvist

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S4 at Helsinki University of Technology (Espoo, Finland) on the 20th of October, 2006, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-8365-4)   [4621 KB]
Dissertation is also available in print (ISBN 951-22-8364-6)

Abstract

This thesis focuses on applications of the hologram-based compact range at submillimeter wavelengths. The work is divided into two parts: compact range for antenna radiation pattern measurements, which can be used for testing satellite antennas and compact range for radar cross section (RCS) measurements, which can be used for radar system development, getting data needed for target recognition and target RCS reduction. The RCS range has also been used for measuring the reflectivity level of radar absorbing materials.

Compact antenna test range (CATR) has been developed and used for antenna measurements at 322 GHz and also successfully demonstrated at 650 GHz. A large-sized CATR was built for measuring a 1.5-meter reflector antenna ADMIRALS RTO at 322 GHz. Assembly of the CATR, testing of the antenna and the disassembly were all done within two months. The 3-meter hologram was constructed from three pieces of patterned copper-plated Mylar, which were joined together by soldering. The quiet zone had a 1.2 dB amplitude dip and a saddle-shaped equiphase surface (p-p deviation 250°). The co-polar radiation pattern of the RTO was measured at vertical polarization. The measured radiation pattern agrees reasonably well with the simulated one. The measured 3 dB beam width is 0.086° (E-plane) and 0.050° (H-plane) as the simulated widths are 0.053° and 0.045°. Differences between the simulated and measured patterns are partly caused by the antenna structure itself and partly by the measurement range.

A compact range based on a phase hologram was developed for RCS measurements. The hologram structure used in these measurements was fabricated on a 5 mm thick, 28 cm × 24 cm Teflon plate. In the horizontal and vertical directions the quiet-zone field amplitude and phase ripples are 3.3 dB and 23°, peak-to-peak, and 0.9 dB and 23°, peak-to-peak, respectively. The quiet-zone diameter is 12 cm. Radar cross sections of a cylinder and a "missile like" target were both simulated and measured. All the main features of the RCS could be seen from the results. The results are very promising. The range was also used for measuring reflectivity of absorbing materials. RCS method was used and the backscattered reflection was measured with horizontal and vertical polarizations in plane-wave conditions. The results agree well with those obtained in the previous studies and complement them with new materials, frequency, and angle information. The result can also be used in CATR development.

This thesis consists of an overview and of the following 7 publications:

  1. A. Lönnqvist, J. Ala-Laurinaho, J. Häkli, T. Koskinen, V. Viikari, J. Säily, J. Mallat, J. Tuovinen, and A. V. Räisänen, Manufacturing of large-sized amplitude holograms for a submm-wave CATR, Digest of 2002 IEEE Antennas and Propagation Society International Symposium, vol. 4, 2002, pp. 394-397. © 2002 IEEE. By permission.
  2. A. Lönnqvist, T. Koskinen, J. Häkli, J. Säily, J. Ala-Laurinaho, J. Mallat, V. Viikari, J. Tuovinen, and A. V. Räisänen, Hologram-based compact range for submillimeter-wave antenna testing, IEEE Transactions on Antennas and Propagation, vol. 53, no. 10, pp. 3151-3159, Oct. 2005. © 2005 IEEE. By permission.
  3. J. Häkli, T. Koskinen, A. Lönnqvist, J. Säily, V. Viikari, J. Mallat, J. Ala-Laurinaho, J. Tuovinen, and A. V. Räisänen, Testing of a 1.5-m reflector antenna at 322 GHz in a CATR based on a hologram, IEEE Transactions on Antennas and Propagation, vol. 53, no. 10, pp. 3142-3150, Oct. 2005. © 2005 IEEE. By permission.
  4. T. Koskinen, J. Ala-Laurinaho, J. Säily, A. Lönnqvist, J. Häkli, J. Mallat, J. Tuovinen, and A. V. Räisänen, Experimental study on a hologram-based compact antenna test range at 650 GHz, IEEE Transactions on Microwave Theory and Techniques, vol. 53, no. 9, pp. 2999-3006, Sept. 2005. © 2005 IEEE. By permission.
  5. A. Lönnqvist, J. Mallat, and A. V. Räisänen, A phase hologram based compact RCS range for scale models, Proceedings of the 25th Annual Meeting and Symposium of the Antenna Measurement Techniques Association (AMTA 2003), Irvine, CA, USA, Oct. 19-24, 2003, pp. 118-123. © 2003 by authors.
  6. A. Lönnqvist, J. Mallat, and A. V. Räisänen, Phase-hologram-based compact RCS test range at 310 GHz for scale models, IEEE Transactions on Microwave Theory and Techniques, vol. 54, no. 6, part 1, pp. 2391-2397, Jun. 2006. © 2006 IEEE. By permission.
  7. A. Lönnqvist, A. Tamminen, J. Mallat, and A. V. Räisänen, Monostatic reflectivity measurement of radar absorbing materials at 310 GHz, IEEE Transactions on Microwave Theory and Techniques, vol. 54, no. 9, pp. 3486-3491, Sept. 2006. © 2006 IEEE. By permission.

Keywords: hologram, compact range, antenna measurements, radar cross section, submillimeter wave

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© 2006 Helsinki University of Technology

Last update 2011-05-26