where [Z.sub.o,s] is the

impedance matrix corresponding to observation group o and source group s; [I.sub.s] is the coefficient vector of RWG basis functions in group s; [B.sub.o] denotes near neighbors of group o; [T.sub.o,s] is the translator; [D.sub.o] and [A.sub.s] are the disaggregation and aggregation matrices.

The unknown expansion coefficients [MATHEMATICAL EXPRESSION NOT REPRODUCIBLE IN ASCII] can be related utilizing

impedance matrix as follows:

The number of columns and raws of the self-impedance matrix [Z.sub.s] and the mutual

impedance matrix [Z.sub.m] is N by N.

The second one sets the load impedances as the conjugates impedances of the corresponding receiving antennas, the third one sets the

impedance matrix of the matching network as the conjugate of antennas'

impedance matrix and consider the mutual couplings of the matching network, while the last one optimize the impedances of transmission lines between receivers and loads, but it does not take into account the mutual couplings of the matching network existing practically.

To directly generate the

impedance matrix, the position vectors of the source points and field points will be repeatedly computed for diferent orders and consumed time.

After modeling a target with a set of N expansion functions and performing the traditional Galerkin testing for the integral equations, a N x N dense

impedance matrix is generated.

where j = 1,2,..., n, n is the sum of the connection substructures, [mathematical expression not reproducible] refers to the connection

impedance matrix of the jth connection substructure, o denotes the DOF sum of the jth connection substructure, and [z.sub.ab] denotes the connection impedance between ath and bth DOFs that denotes the force needed to act on the bth DOF when the ath DOF happens to be a unit displacement.

The total

impedance matrix contains two parts: self-coupling blocks and mutual coupling blocks.

After obtaining the reduced admittance matrix, the

impedance matrix seen from terminals 1 and 2 is calculated by its inverse.

where [Z] is the system equivalent

impedance matrix and [m] is a fully coupling matrix.

where [Z.sup.GP] is the gear pair

impedance matrix, [V.sup.GP] is the gear pair velocity vector, [F.sup.GP] is the applied external force vector, and [F.sup.mesh] is the static transmission error excitation force vector.

and by substitution of (11) into (10), the scattering parameters are now found in terms of

impedance matrix as follows,