Collinear antenna structure with independent accesses
The invention relates to an antenna structure for transmitting and/or receiving wavelengths of metric frequency or decimetric frequency, characterised in that it comprises n collinear antennas, each antenna comprising a radiating portion comprising a first succession of i coaxial radiating elements about a first axis alternating with at least an additional succession of i radiating elements about another axis, each antenna being independently powered by a coaxial cable, each antenna comprising at least one lower quarter-wave trap and at least one upper quarter-wave trap, at least a first antenna comprising at least one hollow core being configured to receive a coaxial cable intended for powering of another antenna collinear with the first antenna, at least one intermediate quarter-wave trap being arranged between two consecutive collinear antennas around a coaxial cable, and a terminal element.
1. Antenna structure for transmitting and/or receiving metric or decimetric frequency waves, comprising n collinear antennas, where n≤2,
each antenna comprising a radiating portion comprising a first succession of i coaxial radiating elements about a first axis, alternating with at least an additional succession of i coaxial radiating elements, each additional succession being arranged about an axis that is different from the first axis, where i≤2,
each antenna being independently powered by a coaxial cable at the level of an excitation input,
each antenna comprising at least one lower quarter-wave trap arranged between the excitation input and a first end of the radiating portion, and at least one upper quarter-wave trap arranged at a second end of the radiating portion,
at least a first antenna comprising at least n−1 hollow cores extending over the entire length, said hollow cores forming the axes of the successions of coaxial radiating elements and at least one of the hollow cores being configured to receive a coaxial cable intended to power another antenna that is collinear with the first antenna,
at least an intermediate quarter-wave trap being arranged between two consecutive collinear antennas around a coaxial cable, and
a terminal element, arranged at the second end of the radiating portion, after the upper quarter-wave trap, and formed of the hollow core or cores of the antenna.
2. Antenna structure according to claim 1 , wherein the number i of coaxial radiating elements about each axis ranges from two to four.
3. Antenna structure according to claim 1 , wherein each upper quarter-wave trap, each lower quarter-wave trap and each intermediate quarter-wave trap is intersected by a hollow core.
4. Antenna structure according to claim 1 , comprising n collinear antennas, n>2, and each collinear antenna comprises at least n-x hollow cores extending over its entire length, the hollow cores being configured to receive a coaxial cable intended to power another antenna that is collinear with said antenna, with x being the number of antennas opposite the excitation input of said antenna on the antenna structure.
5. Antenna structure according to claim 1 , wherein each terminal element comprises a short-circuit element connecting two hollow cores of the antenna to which it belongs.
6. Antenna structure according to claim 1 , wherein each lower quarter-wave trap comprises two collinear cylindrical quarter-wave sub-traps with identical dimensions and spaced by a radius of the quarter-wave sub-traps.
7. Antenna structure according to claim 1 , wherein each upper quarter-wave trap comprises two parallel cylindrical quarter-wave sub-traps with identical dimensions.
8. Antenna structure according to claim 1 , wherein between each antenna, the antenna structure comprises at least one device for the blocking of sheath currents arranged on each coaxial cable.