Radiation pattern and gain of a corner reflector antenna finite in width are calculated by means of geometrical method for diffraction. The functions

referred to diffraction by the edges and their images are introduced. In the case of an aperture angle not equal to

(

: integer) a finite number of images of a dipole are considered, and the waves diffracted by the apex edge are introduced. The cases of aperture angles

,

and

are computed. The results are compared with the measured results obtained by Cottony and Wilson. In the forward and lateral directions agreements between both results are very good; however, in the rear direction it may be necessary to take into account the effects of the waves diffracted by the upper and lower edges of the reflector, when the length of the corner reflector is not too great.