Patent ID: 8059052

Claim:
An endfire antenna apparatus comprising a dielectric transmission substrate, and a plurality of conductive strip elements placed along the width of the dielectric transmission substrate, wherein the length of the conductive strips are orthogonal to a transmission direction which is parallel to the length of the dielectric transmission substrate, the endfire antenna apparatus transmitting intra-substrate transmission components of an electromagnetic wave inside the dielectric transmission substrate along the transmission direction, transmitting surface transmission components of the electromagnetic wave along a surface of the dielectric transmission substrate along the transmission direction, and radiating a combined electromagnetic wave of the intra-substrate transmission components and the surface transmission components of the electromagnetic wave at an end of the dielectric transmission substrate, wherein the plurality of conductive strip elements compose a multilayer loading structure on at least one side of the dielectric transmission substrate, by which a part of the intra-substrate transmission components of the electromagnetic wave are leaked out of the surface of the dielectric transmission substrate, as the surface transmission components; wherein the multilayer loading structure includes a first conductive strip group of conductive strip elements provided within a first plane, and a second conductive strip group of conductive strip elements provided within a second plane apart from the first plane by a predetermined distance; and the conductive strip elements of the first conductive strip group and the conductive strip elements of the second conductive strip group are formed to be capacitively coupled to each other; wherein in each of the first and second conductive strip groups, at least a part of the conductive strip elements are placed at intervals of a distance of a quarter or less of a reference adjacent distance, the reference adjacent distance defined as a distance for generating spatial harmonics of the electromagnetic wave on the surface of the dielectric transmission substrate along the transmission direction; and wherein the endfire antenna apparatus includes two multilayer loading structures comprising: a first multilayer loading structure provided on a top side of the dielectric transmission substrate, and a second multilayer loading structure provided on a bottom side of the dielectric transmission substrate.