Interactions between nested receiving rhombic antennas

In order to install as many radiating circuits as possible in a given area, consideration has to be given to the operation of antennas in proximity to one another. Therefore, mutual coupling between two nested rhombics and the effect of one rhombic on the radiation pattern of the other were measured. For a ratio of antenna sizes of 2 to 1, the presence of either a coplanar or noncoplanar antenna had no influence on the gain and radiation pattern of the reference rhombic. To determine the minimum acceptable separation, measurements were extended to include rhombics almost equal in size and as close as practicable to each other. For wire separations of the gain of the reference rhombic was reduced by 0.5 dB. For separation the gain was reduced by 1 dB, and for it was reduced by approximately 4 dB. Except for very close spacings, the radiation patterns remained substantially unchanged. Mutual coupling, expressed as transmission loss between the antennas in decibels, varied between -15 and -41 dB.