General Concept

The geometrical mean M g e o is used as the center of the computation spheroid. The radius of the spheroid is r K and can be large to ensure that all objects of the configuration (masts, walls, arms) are inside the spheroid. The radius used is between 500 and 1000 m, depending on the objects of the configuration but the actual value does not influence the accuracy of the results.

Figure 1. Spheroid used for computation.

If a 3D pattern is computed, each point on the spheroid is computed (angle resolution is 1 degree in the horizontal plane and 1 degree in the vertical plane, leading to 360 x 180 values). If only a 2x2D result is required, only 2 x 360 values are determined. The increment / resolution is not fixed to 1 degree. For accelerated computations also 2-degree, and even 5-degree steps can be used.

For each value, the field strength E i s o of the isotropic radiator is determined. As all points on the spheroid have the same distance to the geometrical center point M g e o , it is sufficient to compute the field strength E i s o only once and use the same value for all pixels to be determined on the spheroid.

After this initial step, the (complex) field strength E t of the actual configuration is computed as a superposition of the contributions from all single antennas reaching the point under examination.

The quotient

(1) G = | E t o t | 2 | E i s o | 2

represents the gain in the direction towards the point on the spheroid currently examined. Only the magnitude of the complex field strength is used as the phase is not written in the result. After all points on the spheroid are computed, the resulting pattern is available.