A 64 element broad band volumetric array antenna

We present experimental results obtained from a 64 element volumetric array designed for broad band frequency operation. The experimental volumetric array consists of 64 elements arranged in spherical volume of radius 200 mm. Each element is a 7 segment log periodic dipole array designed to provide wide band operation over the frequency range of 6 GHz to 16 GHz. The elements are fed via semi-rigid coaxial cable supported in a stainless steel tubing for extra rigidity. The current array is configured to provide optimum scan performance in the H-plane as, in this orientation, the coaxial feeds are orthogonal to the radiated E-field. At present the 64 element volumetric array demonstrator has no beam forming network and therefore the array scan performance can not be measured directly. However, the main beam characteristics may be synthesised from a knowledge of the measured embedded element patterns. This approach allows accurate predictions of the array performance that include the effects of inter-element coupling.