Antenna system for broadband satellite communication in the GHz frequency range, comprising horn antennas with geometrical constrictions
An antenna system for wireless communication of data includes at least four horn antennas. Each horn antenna is configured to support communications at two mutually orthogonal linear polarizations. Each horn antenna includes an inner wall enclosing a space and geometric constrictions each protruding inwardly from the inner wall into the space along a corresponding polarization plane of one of the two linear polarizations. At least one of the inner wall or the geometric constrictions has a stepped structure.
1. An antenna system for wireless communication of data, the antenna system comprising:
at least four horn antennas, wherein each horn antenna is configured to support communications at two mutually orthogonal linear polarizations and including:
an inner wall enclosing a space and having a first stepped structure; and
geometric constrictions each protruding inwardly from the inner wall into the space along a corresponding polarization plane of one of the two linear polarizations and having a second stepped structure,
wherein an interval between two opposite geometric constrictions facing each other is larger than zero; and
wherein steps in the first stepped structure have corresponding steps in the second stepped structure.
2. The antenna system according to claim 1 , wherein the geometric constrictions are arranged symmetrically with respect to a central axis of the horn antenna.
3. The antenna system according to claim 1 , wherein:
each step in the stepped structure and corresponding step in the second stepped structure constitute a horn section of the horn antenna;
the interval between two opposite geometric constrictions facing each other decreases from the horn section closest to an aperture of the horn antenna to the horn section closest to a horn end of the horn antenna section by section, and
a lower cut-off frequency of each horn section is lower than a lowest useful frequency of the antenna system.
4. The antenna system according to claim 3 , wherein:
the aperture of the horn antennas is approximately rectangular, and
the interval, d, between the two opposite geometric constrictions in one of the horn sections and an associated edge length, a, of an opening of the horn antenna at the one of the horn sections satisfy:
d
i
≤
p
1
2
π
λ
E
a
2
-
p
2
a
,
where λ ∈ denotes a free-space wavelength of the lowest useful frequency of the antenna system, p 1 is between 0.3 and 0.4, and p 2 is between 0.25 and 0.35.
5. The antenna system according to claim 4 , wherein p 1 =0.35 and p 2 =0.29.
6. The antenna system according to claim 4 , wherein an edge length a 0 of the aperture satisfies:
λ
S
≥
a
0
≥
λ
S
2
,
where λ S denotes a free-space wavelength of a highest useful frequency of the antenna system.
7. The antenna system according to claim 3 , wherein step heights of the horn sections are different from each other.
8. The antenna system according to 1 , wherein at least one of the horn antennas is equipped with at least one of a dielectric cross septum or a dielectric lens.
9. The antenna system according to claim 1 , wherein the horn antennas are filled with dielectric.
10. The antenna system according to claim 1 , wherein an interval between phase centers of two directly adjacent horn antennas is less than or equal to a wavelength of a reference frequency that lies in a transmission band of the antenna system.
11. The antenna system according to claim 1 , further comprising:
a first microstrip line network including first microstrip lines configured to communicate with the horn antennas at a first one of the orthogonal linear polarizations; and
a second microstrip line network separated from the first microstrip line network, and including second microstrip lines configured to communicate with the horn antennas at a second one of the orthogonal linear polarizations.
12. The antenna system according to claim 11 , wherein the first and second microstrip line networks are in a binary tree configuration, such that the first and second microstrip line networks may communicate with the horn antennas in parallel.
13. The antenna system according to claim 11 , wherein:
the first and second microstrip lines are formed on a substrate and routed in cavities of the substrate, and
walls of the cavities are electrically conductive.
14. The antenna system according to claim 13 , wherein the substrate is provided with metal plated-through holes configured to establish an electrical contact between the walls of the cavities.
15. The antenna system according to claim 11 , wherein:
the antenna system includes a plurality of electrically-conductive layers, and
at least one of the electrically-conductive layers is located between the first and second microstrip line networks.
16. The antenna system according to claim 11 , wherein the first and second microstrip lines have dimensions that support both a transmission band and a reception band of the antenna system.
17. The antenna system according to claim 11 , wherein:
the first microstrip lines have dimensions that support a reception band of the antenna system, and
the second microstrip lines have dimensions that support a transmission band of the antenna system.
18. The antenna system according to claim 17 , wherein:
the first microstrip line network is configured so that in the reception band, power contributions of the horn antennas are approximately equal, and
the second microstrip line network is configured so that in the transmission band, power contributions of at least some of the horn antennas are different than one another.
19. The antenna system according to claim 11 , further comprising:
90° hybrid couplers coupled to the first and second microstrip line networks, and configured to produce circularly polarized signals from linearly polarized signals, such that the first and second microstrip line networks may communicate circularly polarized signals with the horn antennas.
20. The antenna system according to claim 1 , further comprising:
frequency diplexers configured to separate signals of a transmission band and signals of a reception band, and communicate the separated signals with the horn antennas.
21. The antenna system according to claim 1 , further comprising:
a polarizer coupled to the horn antennas, and configured to communicate circularly polarized signals with the horn antennas.
22. The antenna system according to claim 21 , wherein the polarizer includes a multilayered meander line polarizer that is mounted in front of apertures of the horn antennas.
23. An antenna array for wireless communication of data, the antenna array comprising:
a plurality of antenna systems, the antenna systems including:
at least four single horn antennas, the horn antennas being configured to support communications at two mutually orthogonal linear polarizations and including:
an inner wall enclosing a space and having a first stepped structure; and
geometric constrictions protruding inwardly from the inner wall into the space along a corresponding polarization plane of one of the two linear polarizations and having a second stepped structure,
wherein an interval between two opposite geometric constrictions facing each other is larger than zero, and
wherein each step in the first stepped structure has a corresponding step in the second stepped structure, and
waveguide networks coupling the antenna systems one to another and configured to communicate data with the antenna systems.
24. The antenna array according to claim 23 , wherein: the waveguide networks include:
a first waveguide network configured to couple signals of a first polarization into or out of the antenna systems, and
a second the waveguide network configured to couple signals of a second polarization into or out of the antenna systems.
25. The antenna array according to claim 24 , wherein:
the first waveguide network includes waveguides having dimensions that support a reception band of the antenna array, and
the second waveguide network includes waveguides having dimensions that support a transmission band of the antenna array.
26. The antenna array according to claim 25 , wherein:
the first waveguide network is configured so that in the reception band, power contributions of the horn antennas are approximately equal, and
the second waveguide network is configured so that in the transmission band, power contributions of at least some of the horn antennas are different than one another.
27. The antenna array according to claim 26 , wherein the second waveguide network is configured so that in the transmission band, the power contributions of the horn antennas that are located at an edge of the antenna array are smaller than the power contributions of the horn antennas that are located in a center of the antenna array.
28. The antenna array according to claim 23 , wherein at least one of the waveguide networks has at least one geometric constriction along a propagation direction of an electromagnetic wave in the at least one of the waveguide networks.
29. The antenna array according to claim 23 , wherein at least one of the waveguide networks includes a single-ridged or double-ridged waveguide.
30. The antenna array according to claim 23 , wherein at least one of the waveguide networks is filled with dielectric.
31. The antenna array according to claim 23 , wherein the waveguide networks include waveguides having dimensions that support both a transmission band and a reception band of the antenna array.
32. The antenna array according to claim 23 , wherein the waveguide networks are in a binary tree configuration, such that the waveguide networks may communicate with the antenna systems in parallel.