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Wideband Measurements of the Forward RCS and the Extinction Cross Section

Publiceringsår: 2012
Språk: Engelska
Sidor: 1-6
Dokumenttyp: Konferensbidrag
Förlag: AMTA

Sammanfattning

This paper describes the development of a method based on measurements of the radar cross section (RCS) in the forward direction to determine the extinction cross section for the 2.5 – 38 GHz frequency range. A conventional anechoic chamber designed for monostatic measurements is used for forward RCS measurements. The extinction cross section is then calculated from the measured forward RCS using the optical theorem.
The motivation for this study is to develop an experimental method that can be used to verify recent theoretical work which shows that the extinction cross section integrated over all frequencies is related to the static properties of the scatterer.
Forward RCS measurements are technically complicated due to the large direct contribution from the transmitting antenna to the received signal. The direct signal has to be subtracted from the total signal at the receiving antenna in order to extract the forward RCS. The efficiency of this subtraction is evaluated in this study by performing long time measurements leading to an estimation of subtraction accuracy as a function of the time between the two measurements.
Two calibration methods are investigated. The first method is the traditional calibration method used in most RCS measurements. It uses a target with known RCS as a calibration target to calibrate the target measurement. The second method that is described here does not require a calibration target. It uses a direct path measurement of the signal to calibrate the target measurement. To the best of our knowledge, the latter method is not in frequent use in the RCS community.
The accuracy of the method is determined using small spheres of different sizes which have a forward RCS that is straightforward to calculate using the Mie series. The method described here is also extended to polarimetric measurements of the forward RCS and hence the possibility to determine the extinction cross section for arbitrarily polarized incident radiation. This is tested using measurements on a small helix coil and comparing with method of moments calculations.

Disputation

Nyckelord

  • Technology and Engineering
  • Bistatic
  • Calibration
  • Extinction Cross Section
  • Forward RCS
  • Measurement
  • Polarimetry

Övriga

Antenna measurements techniques association 34th annual symposium
2012-10-21
Seattle, Colorado
Published
Yes
  • Electromagnetic theory

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