However, it is very difficult to determine that these differences are caused by the dynamic nature of the sea surface, by the different measurement parameters of grazing angle
, or by both of them.
In the following the basic structure is modified to obtain a wider selection for amplitude modulation or to achieve a flat band response without the use of grazing angles
From (13)-(19), we can see that the specular reflection coefficient depends on the grazing angle
. The other parameters can be obtained when a model is given, therefore, the specular reflection coefficient is a function of the grazing angle
[psi], i.e., f ([psi]) = [rho][e.sup.j[phi]].
Again, a broad transmission-loss minimum is evident from a 950 to 1300 km altitude, while the grazing angle
changes from 24 [degrees] to 31 [degrees] over this range.
Because the grazing angles
are different, the reflect coefficients satisfy [[zeta].sub.1] [not equal to] [[zeta].sub.2] [not equal to] [[zeta].sub.3] and [[zeta].sub.3] = [[zeta].sub.1] [[zeta].sub.2].
Meanwhile, the predicted Doppler shifts are always found larger in HH polarization than in VV, but eventually come together at very low grazing angles
, with their values both recovering the free Bragg frequency.
where [Psi] is the grazing angle
. All quantities are defined previously in the geometry for a spherical earth.
At a low grazing angle
, the K distribution has been validated in many literatures that it is a proper model for the high-resolution sea clutter returns [30, 31], which are subjected to shadowing, ducting and multipath propagation [29, 32].
These are paired so that two adjacent ports on one side are optimized for transmission and the next pair of ports on the same side are optimized for grazing angle
(Large Angle Reflectance Infrared, LARI).
So at a grazing angle
, measurements become more surface-sensitive.
To date, radar applications have included directional wave spectrum estimation and study of low grazing angle