High performance low profile antennas
A leaky travelling wave array of elements provide a broadband radio frequency antenna.
1. An antenna array apparatus comprising:
an elongated waveguide having a multi-layer substrate, the substrate having a major axis, a minor axis, an excitation end and a load end, the substrate comprising two or more layers of dielectric material, at least one of the layers being a selected dielectric layer that is spaced apart from an adjacent dielectric layer by an adjustable distance;
a control element, connected to at least one of the dielectric layers, and to thereby electrically scan a radiated beam angle by adjusting the adjustable distance between the selected dielectric layer and the adjacent dielectric layer;
one of the dielectric layers being an outer dielectric layer; and
an array of radiating antenna elements disposed on and electrically coupled to the outer dielectric layer at regularly spaced apart positions along the major axis.
2. The apparatus of claim 1 wherein the control element is one of a piezoelectric or electro-active actuator.
3. The apparatus of claim 1 additionally comprising: a wedge layer disposed adjacent the array of radiating elements.
4. The apparatus of claim 1 wherein the multi-layer substrate operates in a TEM propagation mode.
5. The apparatus of claim 1 wherein the dielectric layers further comprise two or more types of dielectric layers, with a first dielectric layer type having a first dielectric constant alternately disposed with layers of a second dielectric layer type having a second dielectric constant, wherein the second dielectric constant is greater than the first dielectric constant.
6. The apparatus of claim 5 wherein at least one of the first or second dielectric layer types is air.
7. The apparatus of claim 1 wherein the spacing between dielectric layers follows a chirp spacing that ranges from one-quarter of a wavelength of a lower frequency of operation to one quarter of a wavelength of a higher frequency of operation.