Patent ID: 9065176
Filing Date: 2015-06-23
Classification: H01Q

Abstract:
1. A unidirectional traveling-wave (TW) antenna comprising: a vertically stacked structure comprising a conducting ground plane, a feed network, a TW structure, and a planar four-arm TW radiator ensemble which comprises a TW radiator, wherein the vertically stacked structure further comprises a feed ensemble in the center; the feed network being generally a stripline or microstrip printed circuit enclosed by said conducting ground plane and another parallel conducting ground plane as well as side conducting walls, and comprising a single balun, wherein said balun is positioned below the said conducting ground plane and the balanced side of said balun is connected to a twin-lead feed line in the feed ensemble; the feed ensemble comprising a twin-lead transmission line and a mode suppressor, which is conducting for the TW waves at the operating frequencies of said TW antenna and wherein the twin-lead transmission line connects a first pair of opposite arms in the medial portion of the four-arm TW radiator ensemble, and a second pair of opposite arms of the TW radiator ensemble being parasitically excited; wherein the mode suppressor comprising a symmetrical conducting tube enclosing the twin-lead transmission line that is connected to the planar TW radiator ensemble; the unidirectional TW antenna having a thickness, the thickness being less than 0.1 λL, wherein λL denotes the free-space wavelength at the lowest frequency of operation; and wherein the TW structure, the planar TW radiator, the feed ensemble and the TW antenna exhibit a twofold rotational symmetry about the center axis of the antenna.