Wide-scan planar array radiating element
An ESA includes radiating elements having a normal mode radiating element and a superimposed end-fire mode radiating element. The combined normal mode radiating element and and-fire mode radiating element attenuators or variable gain amplifiers for amplitude adjustment, phase shifting, and time delay circuitry and algorithms to drive the normal mode radiating element and end-fire mode radiating element simultaneously to produce radiation patterns that constructively interfere. Alternatively, the radiating elements are fed by a radio frequency (RF) feed and switching integrated circuitry timed to drive the normal mode radiating element and end-fire mode radiating element to effectively produce hemispherical radiation patterns as a function or time/scan angle.
1. An electronically scanned array antenna comprising:
a plurality of radiating elements, each radiating element comprising a normal mode radiating element and an end fire mode radiating element; and
a feed layer configured to apply signals to each normal mode radiating element and end-fire mode radiating element,
wherein each of the plurality of radiating elements produces a gain between 0 and 5 dBi when a scan angle is at a zenith and when the scan angle is at a horizon.
2. The electronically scanned array antenna of claim 1 , wherein the feed layer is configured to apply the signals to each normal mode radiating element and each end-fire mode radiating element simultaneously.
3. The electronically scanned array antenna of claim 2 , wherein the feed layer is configured to apply phase shifts to each signal such that a normal mode radiation pattern of each normal mode radiating element and an end-fire mode radiation pattern of the corresponding end-fire mode radiating element constructively interfere.
4. The electronically scanned array antenna of claim 1 , further comprising at least one processor in data communication with the feed layer and a memory storing processor executable code for configuring the at least one processor to:
determine a current scan angle;
drive each normal mode radiating element when the current scan angle is below a threshold; and
drive each end-fire mode radiating element when the current scan angle is above the threshold.
5. The electronically scanned array antenna of claim 4 , wherein the at least one processor is further configured to:
determine a phase shift for each normal mode radiating element when entering a normal mode; and
determine a phase shift for each end-fire mode radiating element when entering an end-fire mode.
6. The electronically scanned array antenna of claim 4 , further comprising at least one RF switch, wherein the at least one processor is further configured to operate the at least one RF switch according to a time domain multiplexing algorithm to switch between the normal mode radiating element and end fire mode radiating element.
7. The electronically scanned array antenna of claim 1 , wherein each normal mode radiating element comprises a center-shorted annular ring.
8. The electronically scanned array antenna of claim 1 , wherein each end-fire mode radiating element comprises a wire-type radiating element disposed in a space defined by the normal mode radiating element, wherein the normal mode radiating element comprises a printed radiating element with a center void.
9. The electronically scanned array antenna of claim 8 , further comprising a pin shorted patch configured as a coaxial element to drive the wire-type radiating element.
10. A method comprising:
driving a normal mode radiating element to produce a normal mode radiation pattern; and
driving an end-fire mode radiating element to produce an end-fire mode radiation pattern,
wherein:
the normal mode radiating element and end-fire mode radiating element are disposed coincident with each other; and
the coincident normal mode radiating element and end-fire mode radiating element produces a gain between 0 and 5 dBi when a scan angle is at a zenith and when the scan angle is at a horizon.
11. The method of claim 10 , further comprising applying signals to the normal mode radiating element and end-fire mode radiating element simultaneously.
12. The method of claim 11 , further comprising applying phase shifts to each signal such that the normal mode radiation pattern and end-fire mode radiation pattern constructively interfere.
13. The method of claim 10 , further comprising determining a current scan angle, wherein:
driving the normal mode radiating element when the current scan angle is below a threshold; and
driving the end-fire mode radiating element when the current scan angle is above the threshold.
14. The method of claim 13 , further comprising:
determining a phase shift for the normal mode radiating element when entering a normal mode; and
determining a phase shift for the end-fire mode radiating element when entering an end-fire mode.
15. The method of claim 10 , wherein the normal mode radiating element comprises a printed radiating element defining a center void and the end-fire mode radiating element comprises a wire-type radiating element disposed in the center void.
16. A radar system comprising:
an electronically scanned array antenna comprising:
a plurality of radiating elements, each radiating element comprising a normal mode radiating element and an end fire mode radiating element; and
a feed layer configured to apply signals to each normal mode radiating element and end-fire mode radiating element,
wherein each of the plurality of radiating elements produces a gain between 0 and 5 dBi when a scan angle is at a zenith and when the scan angle is at a horizon.
17. The radar system of claim 16 , wherein the feed layer is configured to apply the signals to each normal mode radiating element and each end-fire mode radiating element simultaneously.
18. The radar system of claim 17 , wherein the feed layer is configured to apply phase shifts to each signal such that a normal mode radiation pattern of each normal mode radiating element and an end-fire mode radiation pattern of the corresponding end-fire mode radiating element constructively interfere.
19. The radar system of claim 16 , further comprising at least one processor in data communication with the feed layer and a memory storing processor executable code for configuring the at least one processor to:
determine a current scan angle;
drive each normal mode radiating element when the current scan angle is below a threshold; and
drive each end-fire mode radiating element when the current scan angle is above the threshold.
20. The radar system of claim 19 , wherein the at least one processor is further configured to:
determine a phase shift for each normal mode radiating element when entering a normal mode; and
determine a phase shift for each end-fire mode radiating element when entering an end-fire mode.