Ultra-Wideband Conformal Low-Profile Four-Arm Unidirectional Traveling-Wave Antenna With A Simple Feed

• US 20120249385A1
• Filed: 02/16/2012
• Published: 10/04/2012
• Est. Priority Date: 03/30/2011
• Status: Active Grant

• Current Assignee: Wang Electro-Opto Corporation
• Original Assignee: Wang Electro-Opto Corporation
• Inventors: Wang, Johnson J.H.
• Granted Patent: US 9,065,176 B2
• Time in Patent Office: Days
• US Class Current: 343/731
• CPC Class Codes: H01Q 11/105 using a dielectric support
• CPC Class Codes: H01Q 9/27 Spiral antennas

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.

Claims

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, wherein the vertically stacked structure further comprises a feed ensemble in the center;

the feed network comprising a single balun and a matching output circuit, wherein the balanced side of the single 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, 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 being parasitically excited;

wherein the mode suppressor facilitates TW propagation from the twin-lead transmission line to the planar TW radiator;

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 are symmetrical about the center axis of the antenna.

2. The unidirectional TW antenna as claimed in claim 1, wherein the planar TW radiator is a four-arm Archimedean spiral.

3. The unidirectional TW antenna as claimed in claim 1, wherein the planar TW radiator is a four-arm sinuous antenna.

4. The unidirectional TW antenna as claimed in claim 1, wherein the planar TW radiator is a four-arm log-periodic spiral.

5. The unidirectional TW antenna as claimed in claim 1, wherein the planar TW radiator is a four-arm equiangular spiral.

6. The unidirectional TW antenna as claimed in claim 1, wherein the planar TW radiator is a planar multi-arm frequency-independent structure.

7. The unidirectional TW antenna as claimed in claim 1, wherein the conducting ground surfaces, the TW structure and the TW radiator ensemble are parallel relative to each other.

8. The unidirectional TW antenna as claimed in claim 1, wherein the conducting ground surfaces, the TW structure, and the TW radiator ensemble are of a canonical shape, the canonical shape comprising:

a plane, a cylinder, a sphere, and a cone.

9. The unidirectional TW antenna as claimed in claim 1, wherein the TW structure is a slow-wave structure.

10. The unidirectional TW antenna as claimed in claim 9, wherein the TW antenna having a diameter less than 0.4 λ

_L/SWF, wherein λ

_L is free-space wavelength at the lowest frequency of operation and SWF is a Slow Wave Factor.