GB681697A - Microwave antennas - Google Patents

Abstract

681,697. Aerials. NATIONAL RESEARCH COUNCIL. July 2, 1951 [March 21, 1951], No. 15686/51. Class 40 (vii). Relates to directive microwave aerials of the type disclosed in Specification 669,463 comprising a rectangular wave-guide with a plurality of longitudinal resonant slots spaced longitudinally in one of the broad faces such that adjacent slots are coupled to the guide in reverse phase relationship, the spacing between the centres of adjacent slots being less than 7/8 As and preferably equal to 1/2 #g, where As and #g are the wavelengths in free space and in the guide respectively. According to the present invention, the side lobes produced by such an aerial are reduced by arranging the slots in a collinear manner and corrugating the interior surfaces 24 of the side walls so that the centre line 25 between them is sinuous and lies on opposite sides of adjacent slots. In the Figure, the waveguide is shown in perspective, the slots being formed in the lower broad face and the upper broad face being removed to show the internal construction. The upper face is secured in position by screws driven into tapped holes 22 in the edges 23 of the walls and then sweated to the edges. The wave-guide is terminated by a reflecting plunger spaced 1/4#g from the centre of the end slot.