Planar tri-mode cavity

• US 8,664,807 B2
• Filed: 01/06/2011
• Issued: 03/04/2014
• Est. Priority Date: 01/07/2010
• Status: Expired due to Fees

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Gilbert, Roland A., Blazej, Michael D.
• Primary Examiner(s): Barnie, Rexford
• Assistant Examiner(s): DHILLON, JAGDEEP S
• Application Number:
  US12/985,877
• Publication Number:
  US 20110163610A1
• Time in Patent Office: 1,153 Days
• Field of Search: 307/149, 342/375, 342/372, 342/359, 343/371, 333/126, 333/233, 333/136, 333/124, 333/34, 333/101, 333/109, 333/113, 333/6, 333/83
• US Class Current: 307/149
• CPC Class Codes: H01Q 3/26 varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture H01Q3/12, H01Q3/22, H01Q3/24 take precedence
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields

Abstract

A system and method for distributing the power of an electromagnetic signal is presented. In one embodiment, a power distribution cavity includes, a planar cavity, input ports and output ports. The planar cavity is formed with a metallic sheet in the shape of a star pattern with a plurality of elongated star arms extending from a round center portion of the metallic sheet. The input ports are attached to the round center portion of the metallic sheet for receiving an input signal. The signals entering the cavity from the input ports creating independent resonant modes within the cavity that combine producing a tapered aperture distribution of signals at the output ports. The output ports are attached near to the outward ends of the elongated star arms. The planar cavity is thus configured to propagate electromagnetic fields at the output ports that were excited within the cavity by the input ports.

Claims

1. A power distribution cavity comprising:

a planar cavity comprised of a thin planer metallic sheet with a top side and a bottom side in the shape of a star pattern with a plurality of elongated star arms extending from a round center portion of the thin planer metallic sheet;

a plurality of input ports attached to the round center portion of the thin planer metallic sheet for receiving or transmitting a signal;

output ports attached near outward ends of the elongated star arms, wherein the planar cavity is configured to propagate electromagnetic fields excited at the input ports to the output ports, and wherein the thin planer metallic sheet forms a plane with the plurality of input ports attached to the plane and the output ports attached to that same plane.

2. The power distribution cavity of claim 1 further comprising:

a sheet of dielectric material with the thin planer metallic sheet located on a top surface of the dielectric material; and

a sheet of metal forming a ground plane located under the sheet of dielectric material.

3. The power distribution cavity of claim 2 wherein the sheet of dielectric material and the sheet of metal forming a ground plane extend outwardly beyond the outward ends of the elongated star arms.

4. The power distribution cavity of claim 1 wherein the plurality of input ports comprise:

a transverse electromagnetic mode (TEM) input located near a center of the star pattern, configured to receive a TEM signal;

a first transverse electric (TE) mode input comprised of a pair of diametrically located port with opposing polarities positioned near the center portion of the star pattern to receive a first TE signal;

a second TE input located near the center portion of the star pattern to receive a TE signal that is a phase shifted version of the first TE signal.

5. The power distribution cavity of claim 1 wherein the elongated star arms extend outward from the round center portion of the metallic sheet in an oval pattern.

6. The power distribution cavity of claim 5 wherein the star ends are spread out equal circumferential distances from each other in the oval pattern.

7. The power distribution cavity of claim 5 wherein the plurality of star ends is arranged in a circle with the star ends lying on the circle,

8. The power distribution cavity of claim 5 wherein the plurality of elongated star arms comprises 16 elongated star arms.

9. The slot antenna of claim 1 wherein the metallic sheet is a sheet of copper on a printed circuit board (PCB).

10. A beam forming system comprising:

an array of antennas;

a modal power divider configured to partition a radio frequency (RF) input to generate divided RF signals to excite different RF modes within a tri-mode cavity;

wherein the tri-mode cavity comprises a flat planar metallic sheet with a flat upper surface and a flat lower surface, wherein the flat planar metallic sheet is shaped in a star-burst pattern with a center portion and with a plurality of elongated star arms extending outward from the center portion;

a plurality of input ports connected to the center portion of the star-burst pattern of the flat planer metallic sheet to receive the divided RF signals;

a plurality of output ports connected to generally pointed endpoints of the plurality of elongated star arms extending outward from the center portion, wherein the plurality of output ports are configured to receive exited electromagnetic fields generated by the tri-mode cavity; and

a commutator configured to receive signals from the plurality of output ports to produce array antenna excitations and to switch the array antenna excitations onto the array of antennas to transmit a beam signal in a prescribed direction.

11. The beam forming system of claim 10 further comprising:

a dielectric sheet, wherein the planar metallic sheet is a planar metal sheet deposited on one side of the dielectric sheet.

12. The beam forming system of claim 10 wherein the plurality of elongated star arms generally are generally tapered with a cross-section that is narrows from the center portion of the flat planar metallic sheet to the generally pointed endpoints of the elongated star arms.

13. The beam forming system of claim 10 wherein the modal power divider further comprises:

a balun configured to generate a pair of transverse electric (TE) mode inputs from the RF input and wherein the divided RF signals comprises the pair of TE mode inputs.

14. The beam forming system of claim 10 wherein the planar metal flat sheet is a planar sheet of copper.

15. A method of beam forming comprising:

dividing a radio frequency (RF) signal to produce divided signals;

generating RF power distributed signals based, at least in part, on the divided signals, wherein generating the RF power distributed signals comprises;

inputting the divided signals into a center portion of a thin flat planar metallic sheet with a top surface and a bottom surface, wherein the then flat planar metallic sheet is shaped as a star with radially extending arms that extend outward from the center portion; and

receiving the RF power distributed signals at output ports located at ends of the radially extending arms;

passing the RF power distributed signals through a commutator to produce commutated signals;

sending the communtated signals to an antenna array.

16. The method of claim 15 wherein the passing the RF power distributed signals through the commutator further comprises:

passing the RF power distributed signals through phase adjustment device to produce phase adjusted signals; and

passing the phase adjusted signals through switches to produce the commutated signals.

17. The method of claim 15 wherein the passing the phase adjusted signals through switches further comprises:

passing the phase adjusted signals through single pole 4 throw (SP4T) switches.

18. The method of claim 15 wherein the dividing the RF signal to produce divided signals further comprises:

generating a transverse electromagnetic (TEM) signal, wherein the divided signals include the TEM signal; and

generating a pair of transverse electric (TE) mode signals, wherein the divided signal include the pair of TE mode signals.

19. The method of claim 18 wherein the generating a pair of TE mode signals further comprises:

generating the pair of TE mode signals with a balun.

20. The method of claim 15 wherein the inputting the divided signals further comprises:

receiving the power distributed signals at output ports located at the ends of the radially extending arms where the radially extending arms are generally equally radially spaced apart with the ends of the radially extending arms generally forming a circle pattern.