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Compact wide scan periodically loaded edge slot waveguide array

Imported: 24 Feb '17 | Published: 24 Aug '04

Kuan M. Lee, Reinhardt W. Krueger, Fangchou Yang

USPTO - Utility Patents

Abstract

A unit element of a periodically loaded edge slot array includes a reduced-height waveguide section having top and bottom walls and opposed first and second sidewalls defining a waveguide space. A slot is formed in the first side wall at an angle with respect to a waveguide longitudinal axis. At least one conductive post protrudes from the top wall into the waveguide space. The unit element can be incorporated into sticks of an electronically scanned antenna.

Description

BRIEF DESCRIPTION OF THE DRAWING

These and other features and advantages of the present invention will become more apparent from the following detailed description of an exemplary embodiment thereof, as illustrated in the accompanying drawings, in which:

FIG. 1A is an end view of an exemplary embodiment of a unit element of a periodically loaded edge slot array in accordance with aspects of the invention.

FIG. 1B is a front view of the unit element of FIG.

1A.

FIG. 2 is a graph of the scan angle versus frequency of an embodiment of an array employing the invention.

FIG. 3 shows the slot coupling of an analytic model of a periodically loaded slot edge array as a function of slot depth.

FIG. 4 shows the coupling of the analytic model as a function of slot angle.

FIG. 5 shows the coupling of the analytic model as a function of frequency.

FIG. 6 shows a block diagram of an embodiment of an electronically scanned array (ESA) with monopulse capability and with extended frequency scan using a periodically loaded edge slot array in accordance with aspects of the invention.

FIG. 7A is a diagrammatic front view of a portion of the radiating face of the array comprising the system of FIG.

6.

FIG. 7B is a diagrammatic end view of the portion of the array of FIG.

7A.

FIG. 8 is a schematic diagram of an exemplary embodiment of a low cost active ESA antenna with extended frequency scan capability using a periodically loaded edge slot element in accordance with aspects of the invention, employing one T/R module per stick.

Claims

1. A unit element of a periodically loaded edge slot array, comprising:

2. The element of claim 1, wherein said at least one conductive post consists of first and second posts positioned along the longitudinal axis to straddle the slot.

3. The element of claim 1 wherein said slot has a slot axis which defines an acute angle with a plane of the top wall.

4. The element of claim 3 wherein said acute angle is in the range of 0 to 35 degrees.

5. The element of claim 1, wherein the pass band is an X-band frequency band, and the waveguide section has a height of about 0.20 inch and a width of about 0.58 inch.

6. An electronically scanned antenna (ESA) comprising two interleaved arrays of radiating sticks, each stick having an end-fed, edge-slotted traveling wave type waveguide structure comprising a plurality of unit elements as recited in claim 1.

7. An active electronically scanned antenna (AESA) comprising two interleaved arrays of radiating sticks, each stick an end-fed, edge-slotted traveling wave waveguide structure comprising a plurality of unit elements as recited in claim 1, and a plurality of transmit/receive (T/R) modules.

8. A periodically loaded edge slot array, comprising:

9. The array of claim 8, wherein each of said plurality of conductive posts are positioned along the longitudinal axis.

10. The array of claim 8 wherein said plurality of slots each has a slot axis which defines an acute angle with a plane of the top wall.

11. The array of claim 10 wherein said acute angle is in the range of 0 to 35 degrees.

12. The array of claim 8, further including a feed system for end feeding each waveguide with excitation signals.

13. The array of claim 8, wherein the pass band is an X-band frequency band, and the waveguide section has a height of about 0.20 inch and a width of about 0.58 inch.

14. An active electronically scanned antenna (AESA) comprising:

15. The antenna of claim 14, further comprising:

16. The antenna of claim 14, wherein said at least one conductive post, for each unit element, includes first and second posts positioned along the longitudinal axis to straddle the slot.

17. The antenna of claim 14, wherein said slot for each unit element has a slot axis which defines an acute angle with a plane of the top wall.

18. The antenna of claim 17, wherein said acute angle is in the range of 0 to 35 degrees.

19. The antenna of claim 14, wherein each of said reduced-height waveguide sections has a reduced width.

20. The antenna of claim 19, wherein the antenna has an operating frequency pass band bounded by a low frequency and a high frequency, and wherein the low frequency is below a cutoff frequency for the reduced height, reduced width waveguides in the absence of the at least one conductive post, the waveguide adapted for evanescent mode operation in the pass band below said cutoff frequency.

21. The antenna of claim 20, wherein the pass band is an X-band frequency band, and the waveguide section has a height of about 0.20 inch and a width of about 0.58 inch.