Since lai-lainea* Ala-Iart Clan, then Ian (1-C)* laire) and hence Iar= Iam.../(1-C). Finally, the isotrope correction will be K= 1/(1-C), which only depends on the geometry parameters of the radiometer and the angle ø and can be calculated for any orientation of the device. K can be numerically evaluated once the dependences of b, R, and sin/, on ð are obtained from geometrical arguments. Let us consider the reference frame C which is solid with the circle limited by the band, centered at the center of the circle and having the x-axis directed along the diameter A'B'(see Fig. 1). The coordinates ofageneric point Pofthe band will be X= R cosô, Y.= R sinô, Z,= 0. Let us now consider the reference frame Rrotated by an angle ø around the x-axis [Fig. 2 (a)]. Thus