Travelling wave antenna feed structures
Techniques for implementing series-fed antenna arrays with a variable dielectric waveguide. In one implementation, coupling elements with optional controlled phase shifters are placed adjacent each radiating element of the array. To avoid frequency sensitivity of the resulting array, one or more waveguides have a variable propagation constant. The variable waveguide may use certain materials exhibiting this phenomenon, or may have configurable gaps between layers. Plated-through holes and pins can control the gaps; and/or a 2-D circular or a rectangular travelling wave array of scattering elements can be used as well.
1. An antenna apparatus comprising:
a dielectric waveguide formed of two or more layers, with gaps formed between the layers;
a control element arranged to adjust a size of at least one of the gaps, where the control element includes at least one piezoelectric, electroactive material, or mechanical position control;
a plurality of radiating antenna connections disposed adjacent the waveguide; and
a plurality of couplers, with a coupler disposed between the dielectric waveguide and each radiating antenna connection.
2. The apparatus of claim 1 additionally comprising:
a delay element disposed between each coupler and radiating antenna connection.
3. The apparatus of claim 1 wherein the dielectric waveguide additionally comprises:
a pair of elongated, rectangular waveguides, each waveguide having a top surface, a bottom surface, an excitation end, and a load end.
4. The apparatus of claim 3 wherein the radiating antenna connections are disposed between each of the pair of waveguides along the top surface.
5. The apparatus of claim 4 wherein each coupler is disposed between a selected one of the pair of waveguides and a selected one of the radiating antenna connections.
6. The apparatus of claim 5 wherein each coupler is a quadrature coupler.