Patent ID: 8207905
Filing Date: 2012-06-26
Classification: H01Q

Abstract:
1. A unitary antenna feed structure for a backfire dielectrically loaded antenna for operation at a frequency greater than 200 MHz, the antenna having a cylindrical insulative core which is made of a solid dielectric material and which has axially directed proximal and distal surfaces, a cylindrical side surface and a passage extending through the core from the distal surface to the proximal surface, and having a three-dimensional antenna element structure which includes at least one pair of elongate conductive antenna elements disposed on or adjacent the core side surface and which defines an interior volume at least the major part of which is occupied by the solid dielectric material of the core, wherein the feed structure comprises the unitary combination of: a transmission line section comprising a length of transmission line for sliding installation in the core passage so as to pass through the core, the transmission line section having at a distal end thereof a first conductor and a second conductor; and a matching section in the form of a laminate board which extends laterally outwardly from the distal end of the transmission line section and which has proximally directed conductive surface portions for connection to respective conductors of the antenna element structure on the core distal surface, the laminate board including at least a shunt matching capacitance; the arrangement of the feed structure being such that, when it is installed in the core with the laminate board over the core distal surface, the first and second conductors of the transmission line section are coupled to respective antenna elements of said pair of antenna elements with the capacitance forming a shunt capacitance across said conductors.