Spiral surface electromagnetic wave dispersive delay line
Dispersive properties of a linear dispersive delay line are retained in a spiral configuration by constraining the radius of curvature depending on a desired propagation mode. The compact form factor spiral can be either a continuous spiral or a piecewise linear approximation. The spiral comprises a highly dielectric waveguide such as titanium dioxide or barium tetratitanate. Preferably, a spacer with a low dielectric constant and a microstrip are disposed on the top surface. The microstrip prevents attenuation of low frequencies, thereby increasing the operating frequency range. A second dielectric spacer and a second microstrip can be deposited on the bottom surface of the waveguide. Alternatively, the bottom surface of the waveguide can face a ground plane. The waveguide can be fed by horns or half-horns.
1. A surface electromagnetic wave dispersive delay line, comprising:
a waveguide manufactured from a dielectric material, the waveguide having a top surface and a bottom surface;
a first microstrip disposed on the top surface of the waveguide, separated from the top surface of the waveguide by a dielectric spacer;
feed elements coupled to the waveguide; and
wherein the dispersive delay line is arranged in a spiral following a curvature defined by a desired transmission mode.
2. The dispersive delay line of claim 1 wherein the feed elements are horn antennas.
3. The dispersive delay line of claim 1 wherein the dispersive delay line is disposed on a ground plane.
4. The dispersive delay line of claim 1 wherein a second microstrip is disposed on the bottom surface of the waveguide, separated from the bottom surface of the waveguide by a second dielectric spacer.
5. The dispersive delay line of claim 1 wherein the desired transmission mode is an HE11 transmission mode.
6. The dispersive delay line of claim 1 wherein the dielectric material of the waveguide is titanium dioxide.
7. The dispersive delay line of claim 1 wherein the dielectric material of the waveguide is barium tetratitanate.
8. The dispersive delay line of claim 1 wherein the spiral is an Archimedean spiral.
9. The dispersive delay line of claim 1 wherein the dispersive delay line is constructed in a continuous fashion.
10. The dispersive delay line of claim 1 wherein the dispersive delay line is constructed from linear slabs of the dielectric material in a piecewise linear fashion, the arrangement of the slabs following the curvature defined by the desired transmission mode.
11. The dispersive delay line of claim 1 wherein a thickness of the dispersive delay line is constant over a length of the waveguide.