Approximate calculation method for window specification of antenna with medium cover

When an antenna with a medium cover is used, the window specification of the antenna must be determined in order to maintain its radiation characteristics. An approximate estimation can be made on the opening according to the calculation of the electromagnetic energy transmitted within the radiation cone of a dipole antenna. Such an estimation is comparatively accurate for directional antennas since a dipole radiator is semi-spherically isotropic while antennas of other types have radiation cones with a small radiation angle /spl theta//sub 0/ in characteristic. As an approximate method, it may be used to calculate the antenna's window specification, disregarding the pattern distortion induced by the window. Such a method is based on the calculation of the electromagnetic energy radiated by the antenna through the medium cover, whose thickness is d. Thus window specification of the antenna is determined to ensure that most part of the radiated electromagnetic energy can pass through the window.