Horizontally aligned particles. Positive values cause the polarization state to move toward the H polarization point by enhancing the H component of the signal relative to the V component. Positive therefore decreases . Q therefore remains constant and the polarization state changes along a circle parallel to the U-V plane. A positive would cause to increase, but for horizontally oriented particles is negative and therefore changes the polarization state in the same direction as .
Aligned particles produce an unpolarized component when the particles have a variety of shapes.
The condition for this being true is that the polarization state remains in the vicinity of the - plane, which will generally be the case if the radar transmits nearly equal H and V powers and is not depolarized by an unusual amount. In the vicinity of the - plane, therefore, shape variability changes the polarization state in the radial direction. The degree of polarization is reduced by the same amount as , namely by the fractional shape correlation coefficient f . In other words, they do not depend on the particular value of . Thus, circular, slant linear, or elliptical polarizations may be transmitted with the same effect, as long as they contain the same relative amounts of H and V power.