The Use of Method CLEAN and the Successive Projections Algorithm to Speed Antenna Measurements

摘要

In antenna measurements, it is well known that unwanted reflections contain useful information about the test antenna pattern. When time-gating is used to separate the direct path impulse from the reflections, this information is discarded. However, the information can be used to help reconstruct the test antenna pattern, thereby decreasing the number of measurements required by a substantial factor. This paper details solutions based on sparse matrix methods to overcome the excessive time required for measuring antenna patterns. The solutions also remove the effects of reflections, either by time-gating or by using the information about the test antenna pattern contained in the reflections. Using the algorithm CLEAN significantly improves the contrast of sparse data sets. There is also a substantial improvement in the SNR, both for situations with no extraneous scatterers and with an extraneous scatterer deliberately introduced. Moreover, the information about the test antenna pattern contained in the unwanted reflections may be incorporated into the reconstruction of the pattern by using a successive projection algorithm. When the number of measurements used exceeds a prescribed minimum value, the algorithm improves the contrast of the above CLEAN results by a useful amount.