Phased array excited multi-mode waveguide with omnidirectional coverage and beam steering
An antenna for omnidirectional coverage and directional beam forming includes a multimode biconical waveguide with a first conical structure having a first base and a first apex, a second conical structure having a second base and a second apex, the first apex facing the second apex, and a radiation aperture. There is a coaxial interface between the first conical structure and the second conical structure that includes a coaxial waveguide to direct electromagnetic (EM) energy into the radiation aperture. An active electronic phased array (ASEA) included with the antenna controls independent sources of EM wave energy that excite multiple modes of the multimode biconical waveguide and provide omnidirectional radiation and directional beam steering.
1 . An antenna for omnidirectional coverage and directional beam forming comprising:
a multimode biconical waveguide including:
a first conical structure having a first base and a first apex,
a second conical structure having a second base and a second apex, the first apex facing the second apex,
a radiation aperture, and
a coaxial interface between the first conical structure and the second conical structure that includes a coaxial waveguide to direct electromagnetic (EM) energy into the radiation aperture, and
an active electronic phased array (ASEA) configured to control independent sources of EM wave energy that excite multiple modes of the multimode biconical waveguide and provide omnidirectional radiation and directional beam steering.
2 . The antenna in claim 1 , wherein the omnidirectional coverage includes an omnidirectional antenna coverage pattern in azimuth with controllable gain near a horizon.
3 . The antenna in claim 2 , wherein the controllable gain near the horizon is in a range of about 0 dB-20 dB.
4 . The antenna in claim 1 , wherein the directional beam steering includes one or more radiation beams steerable in elevation.
5 . The antenna in claim 1 , wherein the ASEA is controllable to change radiation beams including nulling in some directions and focused in other directions.
6 . The antenna in claim 1 , wherein the multimode biconical waveguide includes a radiation cavity between facing surfaces of the first conical structure and the first conical structure that defines physical dimensions of the radiation aperture.
7 . The antenna in claim 6 , wherein the radiation cavity includes a dielectric having a relative permittivity in a range of about 1-5.
8 . The antenna in claim 6 , wherein the radiation cavity is a vacuum.
9 . The antenna in claim 6 , wherein the radiation cavity is at least partially filled with foam.
10 . The antenna in claim 1 , wherein the multimode biconical waveguide is a monolithic structure.
11 . The antenna in claim 1 , wherein the ASEA includes an array of radiating elements coupled to multiple modes in the coaxial waveguide.
12 . The antenna in claim 11 , wherein the array of radiating elements is formed within an area having a shape corresponding to a cross section of the coaxial waveguide.
13 . The antenna in claim 11 , wherein a number of radiating elements in the array of radiating elements includes a range of about 4 to 256 elements and are configured to excite a number of modes in a range of about 1 to 20 modes in the coaxial waveguide.
14 . The antenna in claim 1 , wherein the multiple modes of the multimode biconical waveguide include transverse electromagnetic (TEM), transverse electric (TE), and transverse magnetic (TM) modes.
15 . A system comprising:
an antenna for omnidirectional coverage and directional beam forming including a multimode biconical waveguide having a first conical structure having a first base and a first apex, a second conical structure having a second base and a second apex, the first apex facing the second apex, a radiation aperture, a coaxial interface between the first conical structure and the second conical structure that includes a coaxial waveguide to direct electromagnetic (EM) energy into the radiation aperture, and an active electronic phased array (ASEA) configured to control independent sources of EM wave energy that excite multiple modes of the multimode biconical waveguide;
an amplitude and phase-shifting network configured to provide an amplitude control signal and a phase control signal to at least some of the independent sources of EM wave energy to generate a predetermined number of modes in the coaxial waveguide; and
processing circuitry configured to generate input signals to the amplitude and phase-shifting network associated with a steerable radiation pattern such that the antenna provides omnidirectional radiation and directional beam steering.
16 . The system in claim 15 , wherein the omnidirectional coverage includes an omnidirectional antenna coverage pattern in azimuth with the processing circuitry configured to generate input signals to the amplitude and phase-shifting network to control a gain near a horizon.
17 . The system in claim 16 , wherein the gain near the horizon is in a range of about 0 dB-20 dB.
18 . The system in claim 15 , wherein the directional beam steering includes one or more radiation beams steerable in elevation.
19 . The system in claim 15 , wherein the processing circuitry is configured to generate input signals to the amplitude and phase-shifting network to control the ASEA to change radiation beams including nulling in some directions and focused in other directions.