Holographic techniques to improve antenna measurements

Abstract

This chapter has analysed the use of holographic techniques for the improvement of the quality of antenna measurements through post-processing techniques. Holographic techniques and the use of plane wave expansion of the radiated field allow an easy way of expression of the radiated field of the antenna. This plane wave expansion is directly related with the sources of the antenna in a plane through an FFT. The use of the FFT allows a very fast calculation, and the results can be practically obtained in real time.The chapter has explored the use of these techniques for echo reduction, increase of SNR, reduction of truncation errors and leakage detection and cancellation. The main advantage of this technique is the required time and reduced computer requirements. These advantages make this technique very useful for some applications. The main drawbacks are the use of planar surfaces, which makes this technique very appropriate for aperture or planar antennas, but not so good for other kind of antennas. However, the sources can be reconstructed in a plane in front of the antenna. Also, the use of holographic techniques makes these techniques appropriate for antennas radiating in one hemisphere. Again, aperture or planar antennas are the most pertinent for the use of these algorithms. In the previous chapter, a more general technique calculating electromagnetic currents on a surface enclosing the antenna has the advantage of the application for a general antenna, but the required time is much higher.