Antenna arrangement
An antenna arrangement can produce omni-directional polarisations of two or more types and comprises a compact arrangement of a dipole with array comprising first and second conductors in parallel planes separated by a printed circuit board and laid on the printed circuit board for generating horizontally polarised signals. A monopole arrangement comprises a third conductor substantially orthogonal to the planes of the first and second conductors and arranged so that one of the first and second conductors acts as a ground plane for the third conductor.
1. An RF antenna arrangement for transmitting two or more polarisations of radio signal, comprising:
a dipole array comprising first and second conductors comprising tracks laid on opposing surfaces of a printed circuit board and arranged in parallel planes separated by the printed circuit board and having connections for an RF feed, the first and second conductors cooperating for generating horizontally polarised RF signals;
the first conductor including a central portion and orthogonal tracks extending outwardly from the central portion and the second conductor including a central portion and orthogonal tracks extending outwardly from the central portion, the central portion and tracks of the second conductor on a surface aligned with the central portion and tracks of the first conductor on the opposing surface;
a monopole arrangement comprising a third conductor extending substantially orthogonal to the parallel planes and extending from a central portion of the first and second conductors and having connections for an RF feed for generating vertically polarised RF signals;
wherein the connections for the RF feeds for the first, second and third conductors are arranged so that the second conductor is connected as a common ground for the RF feed for the monopole arrangement whereby the second conductor acts as a ground plane for the third conductor, thereby providing a compact dual polarised omni-directional antenna.
2. An RF antenna arrangement according to claim 1 , wherein the third conductor is connected at the central portion of the second conductor.
3. An RF antenna arrangement according to claim 2 , wherein the aligned first and second conductors with central portions and orthogonal tracks are each generally cross shaped.
4. An RF antenna arrangement according to claim 1 , wherein the third conductor extends on one side of the printed circuit board and the second conductor is on an opposite side of the printed circuit board.
5. An RF antenna arrangement according to claim 1 , wherein the feeds for the first, second and third conductors comprise coaxial cables with inner and outer conductors, and wherein the connections are arranged so that the outer conductors connect to the second conductor.
6. An RF antenna arrangement according to claim 1 , wherein the central portion of the second conductor is enlarged relative to the central portion of the first conductor.
7. An RF antenna arrangement according to claim 6 , wherein the connections are at the enlarged central portion of the second conductor.
8. An RF antenna arrangement according to claim 1 , wherein the aligned first and second conductors with central portions and orthogonal tracks are generally cross shaped.
9. A broadcast system comprising one or more antenna arrangements according to claim 1 .
10. A television camera comprising one or more antenna arrangements according to claim 1 .
11. A broadcast system having an RF antenna arrangement for transmitting two or more polarisations of radio signal, comprising:
a dipole array comprising first and second conductors comprising tracks laid on opposing surfaces of a printed circuit board and arranged in parallel planes separated by the printed circuit board and having connections for an RF feed, the first and second conductors cooperating for generating horizontally polarised RF signals;
the first conductor including a central portion and orthogonal tracks extending outwardly from the central portion and the second conductor including a central portion and orthogonal tracks extending outwardly from the central portion, the central portion and tracks of the second conductor on a surface aligned with the central portion and tracks of the first conductor on the opposing surface;
a monopole arrangement comprising a third conductor extending substantially orthogonal to the parallel planes and extending from a central portion of the first and second conductors and having connections for an RF feed for generating vertically polarised RF signals;
wherein the connections for the RF feeds for the first, second and third conductors are arranged so that the second conductor is connected as a common ground for the RF feed for the monopole arrangement whereby the second conductor acts as a ground plane for the third conductor thereby providing a compact dual polarised omni-directional antenna.
12. A broadcast system having two antenna arrangements according to claim 11 , one of the antenna arrangements configured for horizontal and vertical polarisation, the other antenna arrangement configured for left and right circular polarisation.
13. A broadcast system according to claim 12 , wherein the two antenna arrangements are configured to broadcast a MIMO signal.
14. A broadcast system according to claim 12 , wherein the system is configured for one of the DVB standards.
15. A television camera having two antenna arrangements according to claim 11 , one of the antenna arrangements configured for horizontal and vertical polarisation, the other antenna arrangement configured for left and right circular polarisation.
16. A television camera according to claim 15 , wherein the two antenna arrangements are mounted in close proximity, one displaced vertically from the other.
17. A television camera according to claim 15 , wherein the two antenna arrangements are configured to broadcast a MIMO signal.
18. A broadcast system according to claim 13 or a television camera according to claim 17 , having circuitry arranged to pre-code MIMO signals.
19. A broadcast system according to claim 13 or a television camera according to claim 17 , having circuitry arranged to pre-code MIMO signals according to
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connected to the first, second and third conductors wherein P is a cross-coupling matrix with elements s 0 and s 1 and {tilde over (s)} 0 and {tilde over (s)} 1 are intended circular polarisation.