Title :
Ionosphere-induced first and higher order errors for space based SAR
Author :
Belcher, D.P. ; Strangeways, H.J.
Author_Institution :
DSTL Malvern, Worchester
Abstract :
Satellite borne SARs need to be operated at low frequencies (HF, VHF) to obtain good penetration through vegetation. At these lower frequencies the effect of the ionosphere is appreciable and the phase variation (in radians) with frequency is higher order than f -1. The magnitude of these higher order phase terms in f -2 and f -3 (in radians) are determined for all frequencies between 50 and 100 MHz for both magneto-ionic modes and for a range of elevations and azimuths (with respect to the magnetic meridian), time of day, month of the year and R12. Calculations are performed for a realistic 3D electron density distribution including both vertical and horizontal gradients of electron density (given by the NeQuick model) to assess accurately these higher order terms for a SAR at 600 km altitude for different ionospheric conditions.
Keywords :
electron density; ionospheric electromagnetic wave propagation; spaceborne radar; synthetic aperture radar; 3D electron density distribution; NeQuick model; altitude 600 km; frequency 50 MHz to 100 MHz; ionosphere propagation; magneto-ionic modes; phase errors; phase variation; satellite borne radar; synthetic aperture radar; SAR ionosphere propagation plase errors;
Conference_Titel :
Ionospheric radio Systems and Techniques, 2009. (IRST 2009). The Institution of Engineering and Technology 11th International Conference on
Conference_Location :
Edinburgh
Print_ISBN :
978-1-84919-123-4