A spherical antenna in which a slot couples free space outside of a spherical scatterer and an inner antenna region in a form of hollow spherical cavity was solved in the first paper [16], and an analogues configuration with a spherical cavity containing a conducting sphere of smaller radius concentrically nested in it [17].

The system of equations for the spherical antenna under consideration can be formulated by considering continuity conditions for tangential components of the magnetic fields on the inner and outer slot apertures [19]

Thus, using a rigorous definition, the problem for the slotted spherical antenna will be solved using the Equation (2).

This maximum is ensured by optimal matching between the spherical antenna and waveguide.

As opposed to the case of an infinite screen, influence of the real slot width upon radiation properties for a spherical antenna can not be studied directly, if the waveguide cross-sectional dimensions are fixed.

Figure 5 shows the calculated energy characteristics of a spherical antenna for a waveguide with standard cross-section {23 x 10} [mm.

We have also calculated energy characteristics for a spherical antenna design with a low-profile waveguide.

Since the resonant length of spherical antenna is decreased if kR is increased and b is accordingly decreased, level of the maximum radiation could be somewhat increased by shortening of the slot.

Physical validity of constructed mathematical models for a spherical antenna has been confirmed by experimental data, obtained for the prototype model.

In these early stages metallic lens antennas such as metal-lens antennas and wire-grid lens antennas [1], reflector lens antennas [2],

spherical antennas [3], dual lens antennas [4], as well as dielectric lens antennas [5], and substrate lens antennas [6] were successfully investigated.