Wideband dual-mode antenna

1 . A wideband dual-mode antenna comprising:

a dielectric substrate;

a conductive layer disposed on a first face of the dielectric substrate;

two tapered slots formed in the conductive layer so as to define a linear center conductor formed in the conductive layer, wherein the tapered slots narrow to slot-lines having uniform width that are terminated by respective baluns at a feed end of the wideband dual-mode antenna;

two feeds disposed on a second face of the dielectric substrate and configured to feed the two tapered slots at the feed end; and

wherein the two slot-lines follow paths that, at the feed end, transition from being parallel to the center conductor to following meandering paths that curve away from, and then back towards, the center conductor, wherein each meandering path includes three 90-degree curves;

a conductive isolation boundary disposed on a second face of the dielectric substrate and electrically connected to the center conductor, wherein the conductive isolation boundary is electrically connected to the center conductor by at least one via in the dielectric substrate; and

wherein the conductive isolation boundary has the same width as the center conductor.

2 . The wideband dual-mode antenna of claim 1 , wherein the conductive isolation boundary is electrically connected to the center conductor by a plurality of evenly-spaced vias in the dielectric substrate.

3 . The wideband dual-mode antenna of claim 2 , wherein the conductive isolation boundary is made of, and the vias are filled with, a conductive material.

4 . A wideband dual-mode antenna comprising:

a dielectric substrate having first and second faces, wherein the first and second faces are opposite to each other;

a conductive layer disposed on the first face;

two tapered slots formed in the conductive layer, wherein each tapered slot tapers from a mouth at an aperture end to a slot-line having a uniform width at a feed end;

a center conductor formed in the conductive layer so as to separate the two tapered slots such that the center conductor defines an edge of each of the two tapered slots;

two micro-strip conductors disposed on the second face so as to feed the two tapered slots to form two tapered slot antennas; and

a conductive isolation boundary disposed on the second face opposite, and aligned with, the center conductor and electrically connected to the center conductor through a series of vias in the dielectric substrate, wherein the conductive isolation boundary has the same dimensions as the center conductor such that the conductive isolation boundary does not overlap either of the two tapered slots.

5 . The wideband dual-mode antenna of claim 4 , wherein the center conductor is aligned with a center line of the wideband dual-mode antenna.

6 . The wideband dual-mode antenna of claim 5 , wherein the two slot-lines follow paths that, at the feed end, transition from being parallel to the center line to following three 90-degree curves.

7 . The wideband dual-mode antenna of claim 6 , wherein each of the two slot-lines terminate in a respective circular balun.

8 . The wideband dual-mode antenna of claim 5 , wherein the slot-lines, at the feed end, transition from paths that are parallel to the center line to meandering paths that curve away from the center line.

9 . The wideband dual-mode antenna of claim 8 , wherein each meandering path includes three 90-degree curves.

10 . The wideband dual-mode antenna of claim 4 , further comprising a 90-degree hybrid coupler connected to the microstrip conductors such that the tapered slot antennas generate two orthogonal radiation patterns, such that one of the two tapered slot antennas operates in a common mode and the other tapered slot antenna operates in a differential mode.

11 . A wideband dual-mode antenna comprising:

a dielectric substrate having first and second faces, wherein the first and second faces are opposite to each other;

a conductive layer disposed on the first face;

a first slot formed in the conductive layer, wherein the first slot tapers from a first mouth at an aperture end to a first uniform-width slot-line at a first distance from the first;

a second slot formed in the conductive layer so as to define a center conductor in the conductive layer that separates the first and second slots, wherein the center conductor is rectangular from the first and second mouths to the first distance, wherein the second slot tapers from a second mouth at the aperture end to a second uniform-width slot-line at the first distance;

two micro-strip conductors disposed on the second face so as to feed the first and second slots to form first and second tapered slot antennas;

a conductive isolation boundary having the same shape as the center conductor disposed on the second face so as to align with the center conductor, wherein the conductive isolation boundary is electrically connected to the conductive layer through the dielectric substrate; and

wherein the first and second uniform-width slot-lines transition from parallel paths between the first distance and a second distance from the first and second mouths to meandering paths that curve away from, and then back towards, each other between the second distance and a third distance from the first and second mouths, wherein the second distance is greater than the first distance and the third distance is greater than the second distance.

12 . The wideband dual-mode antenna of claim 11 , wherein each meandering path includes three 90-degree curves.

13 . The wideband dual-mode antenna of claim 12 , wherein each of the two slot-lines terminate in a respective balun.

14 . The wideband dual-mode antenna of claim 13 , further comprising a 90-degree hybrid coupler connected to the microstrip conductors such that the tapered slot antennas generate two orthogonal radiation patterns, such that one of the two tapered slot antennas operates in a common mode and the other tapered slot antenna operates in a differential mode.