Title :
Cylindrical near-field measurement error models for NASA scatterometer fan-beam array antenna
Author :
Hussein, Z.A. ; Rahmat-Samii, Y.
Author_Institution :
Jet Propulsion Lab., California Inst. of Technol., Pasadena, CA, USA
Abstract :
The NASA scatterometer antenna is dual-pol fan beam, made up of two separate slotted waveguide-array-fed horns (one for v-pol and one for h-pol polarization), to be used in measuring the backscattered power of the sea surface. Then, the wind velocity can be extracted from these measurements. The antennas are to be calibrated to within 0.25 dB over the main beam with antenna pointing accuracy of 0.05 degrees . In order to achieve this high accuracy, a cylindrical near-field technique by which a probe samples the near field on an imaginary cylindrical surface is used in conjunction with an error analysis to reconstruct the far-field radiation patterns. An efficient and fast algorithm is developed to evaluate the cylindrical wave coefficients with 1D FFT (fast Fourier transform) and numerical integration, from which antenna patterns and directivity are obtained. The results are compared with the 2D FFT.<>
Keywords :
antenna arrays; antenna radiation patterns; backscatter; calibration; horn antennas; measurement errors; oceanographic equipment; radar antennas; remote sensing by radar; 1D FFT; NASA scatterometer fan-beam array antenna; NSCAT antenna; backscattered power; cylindrical near-field measurement error models; cylindrical wave coefficients; error analysis; far-field radiation patterns; fast Fourier transform; numerical integration; sea surface; slotted waveguide-array-fed horns; wind velocity; Antenna measurements; Horn antennas; Measurement errors; NASA; Polarization; Power measurement; Radar measurements; Sea measurements; Sea surface; Slot antennas;
Conference_Titel :
Antennas and Propagation Society International Symposium, 1992. AP-S. 1992 Digest. Held in Conjuction with: URSI Radio Science Meeting and Nuclear EMP Meeting., IEEE
Conference_Location :
Chicago, IL, USA
Print_ISBN :
0-7803-0730-5
DOI :
10.1109/APS.1992.221740