Patent ID: 8400366

Claim:
A radiation efficiency measuring apparatus, comprising: a target antenna to be measured, a measuring antenna arranged at a position spaced apart from the target antenna by a distance dimension of R, an electromagnetic field measuring device, connected to the measuring antenna, for measuring an electromagnetic field radiated by the target antenna, elevation angle switching means for switching an elevation angle φ of the target antenna between first and second angles φ 1 and φ 2 , different from each other by 90 degrees, azimuth angle rotation means for rotating the target antenna to an azimuth angle θ, first radiation pattern measuring means for causing the azimuth angle rotation means to rotate the target antenna to a azimuth angle θ with the elevation angle φ of the target antenna switched to the first angle φ 1 by the elevation angle switching means, and measuring a first azimuth angle plane radiation pattern S 21 (R,θ,φ) with the electromagnetic field measuring device, second radiation pattern measuring means for causing the azimuth angle rotation means to rotate the target antenna to the azimuth angle θ with the elevation angle φ of the target antenna switched to the second angle φ 2 by the elevation angle switching means, and measuring a second azimuth angle plane radiation pattern S 21 (R,θ,φ) with the electromagnetic field measuring device, and radiation efficiency calculating means for calculating a radiation efficiency η of the target antenna on the basis of the first and second azimuth angle plane radiation patterns S 21 (R,θ,φ) measured by the first and second radiation pattern measuring means, wherein η = 4 ⁢ π ⁢ ⁢ R 2 ⁢ ∑ θ ⁢ ∑ ϕ ⁢ S ⁢ ⁢ 21 2 ⁢ ( R , θ , ϕ ) ⁢ sin ⁢ ⁢ θ ⁢ ⁢ Δ ⁢ ⁢ ϕ ⁢ ⁢ Δ ⁢ ⁢ θ λ 2 ⁢ G where λ represents a wavelength of a measuring frequency, G represents a gain of the measuring antenna, Δφ represents a measuring angle step in the elevation angle φ direction, and Δθ represents a measuring angle step in the azimuth angle θ direction.