Dual polarised omnidirectional antenna apparatus

Abstract

A dual polarised omnidirectional antenna apparatus (20) capable of operating in transmit and receive, comprising at least two dual polarised directional antennas (21) configured to be mountable in a substantially equi-spaced distributed array around and pointing away from a platform, wherein the antenna apparatus (20) is configured such that, when operated in transmit, the dual polarised directional antennas operate in phase with each other to deliver a combined omnidirectional, dual polarised, performance. This increases operational bandwidth and mitigates interference effects in communications applications.

Claims

1. A dual polarised omnidirectional vehicle antenna apparatus capable of operating in transmit and receive, comprising at least two dual polarised directional antennas configured outwardly, the apparatus adapted to mount in a substantially equi-spaced distributed array around and pointing away from a vehicle, wherein the antenna apparatus is configured such that, when operated in transmit and/or receive, the dual polarised directional antennas operate in phase with each other to deliver a combined omnidirectional, dual polarised, performance.

2. The dual polarised omnidirectional vehicle antenna apparatus of claim 1, further comprising a power source electrically connected to the dual polarised directional antennas, the power source being configured to power the dual polarised directional antennas in-phase.

3. The dual polarised omnidirectional vehicle antenna apparatus of claim 1, further comprising a signal processor.

4. The dual polarised omnidirectional vehicle antenna apparatus of claim 1, configured to operate at 1800 MHz to 6000 MHz.

5. The dual polarised omnidirectional vehicle antenna apparatus of claim 1, configured to operate at 800 MHz to 2500 MHz.

6. A method of omnidirectional communication to or from a vehicle, the method comprising the steps of: providing the dual polarised omnidirectional vehicle antenna apparatus of claim 1; mounting the dual polarised directional antennas of the antenna apparatus onto a vehicle as a substantially equi-spaced array around and pointing away from the vehicle; providing in-phase power to the dual polarised directional antennas; and receiving a signal or transmitting a signal using the dual polarised omnidirectional vehicle antenna apparatus.

7. A vehicle comprising the dual polarised omnidirectional vehicle antenna apparatus of claim 1.

8. The dual polarised omnidirectional vehicle antenna apparatus of claim 1, further comprising a platform from which the at least dual polarised directional antennas extend outwardly.

9. The dual polarised omnidirectional vehicle antenna apparatus of claim 8, wherein the apparatus is adapted to be mounted to the vehicle such that the platform is proximate to the vehicle and is adapted to be mounted on the vehicle.

10. The dual polarised omnidirectional vehicle antenna apparatus of claim 1, wherein each dual polarised directional antenna comprises a first element in a first polarisation and a second element in a second polarisation that is different from the first polarisation.

11. An omnidirectional vehicle antenna apparatus capable of operating in transmit and receive, comprising at least two directional antennas configured outwardly and adapted to mount in a substantially equi-spaced distributed array around and pointing away from a vehicle, wherein the antenna apparatus is configured such that, when operated in transmit and/or receive, the directional antennas operate: in phase with each other to deliver a combined omnidirectional performance.

12. The omnidirectional vehicle antenna apparatus of claim 11, further configured such that when operated in receive, the directional antennas operate in phase with each other to deliver a combined omnidirectional performance.

13. The omnidirectional vehicle antenna apparatus of claim 11, further comprising a power source electrically connected to the directional antennas, the power source being configured to power the directional antennas in-phase.

14. The omnidirectional vehicle antenna apparatus of claim 11, further comprising a signal processor.

15. The omnidirectional vehicle antenna apparatus of claim 11, configured to operate at 1800 MHz to 6000 MHz.

16. The omnidirectional vehicle antenna apparatus of claim 11, configured to operate at 800 MHz to 2500 MHz.

17. A vehicle comprising the omnidirectional vehicle antenna apparatus of claim 11.

18. An antenna array comprising a plurality of dual polarised directional antennas that are mounted around an exterior surface of a vehicle, wherein the antenna array is configured such that when operated in transmit and/or receive, the plurality of dual polarised directional antennas operate in phase with each other to deliver a combined omnidirectional dual polarised performance radiating away from the vehicle.

19. The antenna array of claim 18, wherein at least some of the plurality of dual polarised omnidirectional vehicle antennas are mounted substantially equi-spaced around the vehicle.

20. An antenna array comprising a plurality of directional antennas that are mounted substantially equi-spaced around and pointing away from a vehicle, wherein the antenna array is configured such that when operated in transmit and/or receive, the plurality of directional antennas operate in phase with each other to deliver a combined omnidirectional performance radiating away from the vehicle.

21. A vehicle comprising an antenna array, the antenna array comprising a plurality of dual polarised directional antennas that are mounted substantially equi-spaced around and pointing away from the vehicle, wherein the antenna array is configured such that when operated in transmit and/or receive, the plurality of dual polarised directional antennas operate in phase with each other to deliver a combined omnidirectional dual polarised performance radiating away from the vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:

(2) FIG. 1 shows an illustration of an embodiment of a dual polarised omnidirectional antenna apparatus;

(3) FIG. 2 shows an illustration of a dual polarised omnidirectional antenna apparatus mounted to a vehicle; and

(4) FIG. 3 shows an illustration of the gain profile of the embodiment of FIG. 2, showing overlapping dual polarised coverage.

DETAILED DESCRIPTION

(5) FIG. 1 shows an illustration of a plurality of dual polarised directional antennas 21 configured as an embodiment of an omnidirectional antenna apparatus 20. Dual polarised directional antennas 21 are shown inside respective protective radomes 22 to protect against damage or abrasion. The radomes 22 are formed from plastic and are transparent to the radio frequencies of operation of antennas 21. Each antenna 21 is electrically connected (via wires 25) to a transmitter 23, itself being electrically connected to power supply 24. The power supply 24 is a portable battery unit (for instance lithium ion battery or other electrolyte based battery, such as would be found in a vehicle). The electrical connections 25 to each antenna 21 are split inside antenna 21 via respective power dividers (not shown) so as to power both antenna elements 21a and 21b in each antenna 21. The power divider inside each antenna 21 equally divides power to the respective first 21a and second 21b antenna elements, and applies zero degrees of phase shift. This ensures the first 21a and second 21b antenna elements in each dual polarised antenna 21 are operated in phase with each other, and that their radiation patterns are substantially uniform. The radiation patterns (vertical and horizontal polarisations, owing to the orthogonal orientations of antenna elements 21a and 21b) for all the dual polarised antennas 21 constructively combine (across the two polarisations) to provide overall dual polarised omnidirectional performance. The antenna elements 21a and 21b are arranged in the same geometrical plane so as to radiate in substantially the same direction.

(6) FIG. 2 shows an illustration of an embodiment of a dual polarised omnidirectional antenna apparatus 25 when mounted to a vehicle 26. Shown in the figure are a plurality of dual polarised antennas 27 mounted on the front, back, and sides of the vehicle (the far side is not shown in figure). The antennas 27 are operated in phase with each other to deliver a combined dual polarised omnidirectional performance radiating away from the vehicle 26.

(7) FIG. 3 shows an illustration of the gain profiles 28 provided by the embodiment of FIG. 2. The figure shows vehicle 26 with a plurality of dual polarised directional antennas mounted thereupon. The dual polarised directional antennas are operated in phase with each other so as to provide an omnidirectional performance radiating away from the vehicle 26 with vertical polarisation 30. The dual polarised antennas simultaneously also provide an omnidirectional performance radiating away from the vehicle 26 with horizontal polarisation 31. The radial distance from the vehicle 26 is intended to illustrate gain (i.e. greater radial distances from the vehicle 26 indicate higher gain).

(8) Whilst the embodiments described indicate dual polarisation being achieved by each antenna comprising two spatially orthogonal antenna elements, other embodiments may comprise spiral antennas that by virtue of being circularly polarised offer components of radiation with both vertical and horizontal polarisations. Such antenna elements may be provided in a cavity backed configuration to achieve the desired directionality.