Apparatus and method for antenna RF feed
An RF feed is provided which is structured as a curved reflector coupled to a sidewall of a waveguide cavity. A radiation source is situated facing the curved reflector. The RF feed may be coupled to a waveguide cavity having radiation elements coupled to top surface thereof, to thereby feed an antenna array. When an antenna array is used, several curved reflector RF feeds may be used, operating in the same or different frequencies.
1. An RF feed comprising:
a parallel plate waveguide comprising a top plate, a bottom plate, and a side wall defining a cavity, wherein the sidewall comprises an opening serving as an excitation port and wherein the top plate and bottom plate are made of metal or a material coated with metal;
a curved reflector situated outside the cavity and coupled to the excitation port, the reflector configured to excite at the excitation port a planar electromagnetic wave in near field regime, such that the planar wave propagates within the waveguide; and
a radiation source provided in the space between the excitation port and the curved reflector and radiating towards the curved reflector.
2. The RF feed of claim 1 , wherein the curved reflector is one of: a three-dimensionally shaped surface, cylindrical, parabolic, or toroidal.
3. The RF feed of claim 1 , further comprising an extension coupled between an opening in the waveguide and the curved reflector.
4. The RF feed of claim 3 , wherein the extension is configured to situate the curved reflector under the waveguide.
5. The RF feed of claim 4 , wherein the radiation source is positioned between the extension and the curved reflector.
6. The RF feed of claim 1 , further comprising a counter-reflector situated opposite the radiation source and facing the curved reflector.
7. The RF feed of claim 1 , wherein the radiation source comprises one of: a metallic pin, a waveguide horn opening, or a microstrip patch.
8. The RF feed of claim 1 wherein the top plate comprises at least one radiation coupling aperture, and further comprising a radiating element extending from the top plate over the coupling aperture, the element comprising a sidewall forming a distal opening spaced apart from the top plate, and the coupling aperture coupling wave energy of the planar electromagnetic wave between the waveguide and the radiating element.
9. The RF feed of claim 1 , further comprising at least one patch radiating element provided on the top surface.
10. The RF feed of claim 1 , further comprising an extension coupled to the opening in the sidewall, and wherein the curved reflector is provided under the bottom plate and is coupled to the extension.
11. The RF feed of claim 1 , wherein the radiation source comprises a plurality of metallic pins arranged linearly.
12. The RF feed of claim 1 , wherein the radiation source comprises a plurality of metallic pins arranged on a curve.
13. The RF feed of claim 1 , wherein the radiation source comprises a plurality of waveguide horns.
14. The RF feed of claim 1 , wherein the radiation source comprises a plurality of microstrip patches.
15. The RF feed of claim 1 , wherein the curved reflector is shaped according to a function designed to reflect radiation received from the radiation source to thereby produce a linear wave front at the opening at the side of the waveguide.
16. The RF feed of claim 1 , further comprising:
a second curved reflector coupled to a second opening at a second side of the waveguide; and
a second radiation source provided in the space between the second opening at the second side of the waveguide and the second curved reflector.
17. The RF feed of claim 16 , wherein the second curved reflector is shaped according to a function designed to reflect radiation received from the second radiation source to thereby produce a second linear wave front at the second opening at the second side of the waveguide.
18. The RF feed of claim 17 , wherein the linear opening and the second opening are at right angles to each other.
19. The RF feed of claim 1 , wherein the radiation source comprises a movable metallic pin.
20. The RF feed of claim 16 , wherein the curved reflector is smaller than the second curved reflector.