Ultra-wideband conformal low-profile four-arm unidirectional traveling-wave antenna with a simple feed
First Claim
1. A unidirectional traveling-wave (TW) antenna comprising:
- a vertically stacked structurecomprising 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 λ
L, wherein λ
L 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.
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Abstract
The invention is a class of planar unidirectional traveling-wave (TW) antenna comprising a planar four-arm TW radiator ensemble, such as a 4-arm spiral, which is fed medially with a twin-lead feed connected with only a pair of opposite arms of the TW radiator, with the other two arms parasitically excited. The use of a mode suppressor enhances the purity of single-mode TW propagation and radiation. The twin-lead feed is connected with the balanced side of a balun, and is impedance matched with the TW radiator on one side and the balun on the other side. This simple feed structure using a single balun is generally smaller and much simpler, and thus much less costly than the conventional feed for a 4-arm spiral, which is a complex one-to-four power divider that contains hybrids, power dividers, couplers, matrices, etc.
18 Citations
10 Claims
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1. A unidirectional traveling-wave (TW) antenna comprising:
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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 λ
L, wherein λ
L 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification