3 ORIENTATIONS OF COUPLER
Couplers can be oriented with the short axis in the X, Y, or Z orientation. The animation above is all three superimposed. Notice the subfrequency RD and Stellated RD. The long body diagonals of the couplers parallel VE radials in the IVM and the short body diagonals are Cartesian axes. So the coupler assimilates both coordinate systems.