Tapered leaky wave ultrawide band microstrip antenna

• US 6,166,693 A
• Filed: 03/09/1999
• Issued: 12/26/2000
• Est. Priority Date: 03/30/1998
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Nalbandian, Vahakn, Lee, Choon S.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): NGUYEN, HOANG V
• Application Number:
  US09/285,185
• Time in Patent Office: 658 Days
• Field of Search: 343/700 MS, 343/895, 343/825
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 13/206 Microstrip transmission line antennas
• CPC Class Codes: H01Q 9/0457 electromagnetically coupled to the feed line

Abstract

The present invention is a microstrip antenna which produces ultrawide band leaky wave radiation. The antenna produces leaky wave radiation, then trs the leaky wave radiation to produce an ultrawide bandwidth. The antenna includes tapered metal patches which taper the radiation. The antenna gives an ultrawide bandwidth performance of greater than a 4:1 ratio.

Claims

1. An antenna comprising:

a means for producing leaky wave radiation;

a means for tapering the leaky wave radiation;

said means for producing leaky wave radiation having a means for matching an input impedance of the antenna to a leaky wave mode of propagation;

said leaky wave radiation having a frequency range;

said means for producing leaky wave radiation also having a means for preventing and suppressing radiation caused by a plurality of surface mode excitations;

a microstrip having a plurality of layers; and

a plurality of patches located on the plurality of layers;

wherein the locations and widths of the plurality of patches on the plurality of layers are such that the input impedance of the antenna matches the leaky wave propagation mode of the radiation.

2. The antenna of claim 1, wherein the frequency range for the leaky wave radiation produced by the antenna is:

##EQU5## where f_c is the cutoff frequency of the leaky wave mode of propagation and ε

_r is a dielectric constant of a substrate of the antenna.

3. The antenna of claim 2, wherein the means for tapering the leaky wave radiation comprises at least one strip which has a gradually tapered shape from wide to narrow.

4. The antenna of claim 3, wherein the gradually tapered shape is at least partially linear.

5. The antenna of claim 3, wherein the gradually tapered shape is at least partially hyperbolic.

6. The antenna of claim 3, wherein the gradually tapered shape is at least partially a transcendental function.

7. The antenna of claim 3, wherein the gradually tapered shape is at least partially a Chebyshev polynomial.

8. A method of producing a tapered ultra wide band traveling wave from a microstrip antenna comprising the steps of:

producing leaky wave radiation

tapering the leaky wave radiation;

matching an input impedance of the antenna to a leaky wave mode of propagation;

preventing and suppressing radiation caused by a plurality of surface mode excitations;

forming said microstrip with a plurality of layers;

locating a plurality of patches on said plurality of layers;

positioning the locations and widths of the plurality of patches on the plurality of layers such that the input impedance of the antenna matches the leaky wave propagation mode of the radiation; and

said leaky wave radiation having a frequency range expressed in the equation;

##EQU6## where said f_c is the cutoff frequency of the leaky wave radiation and said ε

_r is a dielectric constant of a substrate of the antenna.

9. An article of manufacture comprising:

a tapered ultra wide band traveling wave formed by;

producing leaky wave radiation with a means for producing leaky wave radiation;

tapering the leaky wave radiation with a means for tapering the leaky wave radiation;

a means for producing leaky wave radiation having a means for matching an input impedance of the antenna to a leaky wave mode of propagation;

said leaky wave radiation having a frequency range;

said means for producing leaky wave radiation also having a means for preventing and suppressing radiation caused by a plurality of surface mode excitations;

a microstrip having a plurality of layers;

a plurality of patches located on the plurality of layers;

wherein the locations and widths of the plurality of patches on the plurality of layers are such that the input impedance of the antenna matches the leaky wave propagation mode of the radiation; and

the frequency range of the leaky wave radiation expressed in the equation;

##EQU7## where f_c is the cutoff frequency of the leaky mode and ε

_r is the dielectric constant of the substrate of the antenna.

10. An antenna comprising:

a microstrip for producing leaky wave radiation, said microstrip having an upper layer and a lower layer; and

a plurality of patches located on the upper and lower layers, where at least one of the patches is tapered for tapering the leaky wave radiation.

11. The antenna of claim 10 wherein the plurality of patches comprise

a first tapered patch located on the lower layer of the microstrip;

a second tapered patch located on the lower layer of the microstrip;

a gap located on the lower layer of the microstrip, in between the first and second patches;

a third tapered patch located on the upper layer, above the gap, so that the third patch is electromagnetically coupled to the lower layer;

wherein the three patches and the gap are positioned so that the input impedance of the antenna matches a leaky wave propagation mode of the radiation.

12. The antenna of claim 11 wherein:

the patches comprise a conductive material;

the upper and lower layers comprise a dielectric material;

a conductive ground plane is located on the lower layer; and

an input probe for providing a source of electromagnetic energy to the antenna is coupled to the lower layer and the first patch.

13. The antenna of claim 10, wherein the shape of the at least one tapered patch is at least partially selected from the group consisting of:

a linear shape, a hyperbolic shape, a Chebyshev polynomial shape, a transcendental function shape.

14. The antenna of claim 10, wherein the frequency range of the leaky wave radiation is:

##EQU8## where f_c is the cutoff frequency of the leaky mode and ε

_r is the dielectric constant of the substrate of the antenna.