The Hooded Antenna: An Approach to Meaningful Field Strength Measurements in Shielded Enclosures

A technique is described for significantly reducing the effect of multipath interference on field strength measurements made in conventional shielded enclosures by hooding the receiving antenna. Field strength measurements in a shielded enclosure and corresponding measurements in the open field were made at frequencies from 1 to 7 Gc/s with and without an antenna hood. It was found that when the appropriate insertion loss constants are applied to the hooded antenna data taken in a shielded enclosure, the agreement between these data and the data from the same experiments performed in the open field without a hood is excellent. Principal advantages of the hooded antenna over anechoic chambers include reduced cost, reduced inside space requirements for absorbing material, and applicability of use in most existing shielded enclosures.