Patent Application
20090231221
The present invention relates to a rod antenna according to claim 1 and to a method for operating a rod antenna according to claim 14.
In the recent past, the requirements for an antenna have significantly increased. There is the need to have antenna systems which can be flexibly adapted to the requirements of different applications. Further, it is preferred to have a radiation pattern with a small size, small sidelobe, a high directivity, a high gain, integration capability with planar circuitry and an antenna which in addition is cost-effective.
From the state of art rod antennas are known where the feedings is realised by a three-dimensional wave guide feeding. For example, the document Kobayashi et al. “Dielectric Tapered Rod Antennas For Milimeter-Wave Applications”, IEEE Transactions on Antennas and Propagation, January 1982, discloses the feeding of dielectric rod antennas by a metal waveguide, whereby the waveguide is matched by a launching horn. The problem that arises with a rod antenna according to the state of art is that with the waveguide feeding the antenna cannot be flexibly adapted to different requirements.
The object of the present invention is therefore to provide a rod antenna that can be easily implemented and adapted to the requirements of different applications such as planar circuitry.
The above-mentioned object is achieved by a rod antenna according to claim 1.
The rod antenna according to the present invention comprises a two-dimensional patch for radiating and/or receiving an electromagnetic wave, said patch extending along a plane defined by two coordinate axes being orthogonal to each other, a feeding line coupled to the patch for transferring signal energy to and/or from the patch, a dielectric rod for radiating and/or receiving said electromagnetic wave, said rod extending longitudinally from the patch in direction of a third coordinate axis being outside of the plane defined by the first two coordinate axes and a metal holder coupled to the patch and to the rod for transferring said electromagnetic wave between the patch and the rod.
The above-mentioned object is further achieved by a method for operating a rod antenna according to claim 14.
The method according to the present invention comprises the steps of radiating and/or receiving an electromagnetic wave by a two-dimensional patch, said patch extending along a plane defined by two coordinate axes being orthogonal to each other, transferring signal energy to and/or from the patch by a feeding line coupled to the patch, radiating and/or receiving said electromagnetic wave by a dielectric rod, said rod extending longitudinally from the patch in direction of a third coordinate axis being outside of the plane defined by the first two coordinate axes and transferring said electromagnetic wave between the patch and the rod by a metal holder coupled to the patch and to the rod.
Preferably, the feeding line is extending along one of the first two coordinate axes or is orthogonal to the first two coordinate axes.
Further preferably, the length of the metal holder is equal to the wavelength of the said electromagnetic wave.
In one embodiment the length of the metal holder is equal to a half of the wavelength of said electromagnetic wave.
The rod may be extending into a direction being orthogonal to the plane defined by the first two coordinate axes.
Advantageously the rod has an oval, elliptical, circular or rectangular cross section.
The rod may have a cross section constant in size and shape over the whole length of the rod.
The rod may be tapering toward one end.
Preferably the rod has a top plane.
The normalised direction of the top plane may be extending in direction of the third coordinate axis.
The normalised direction of the top plane may be extending into a direction different from the direction of third coordinate axis.
Preferably an antenna array comprises at least two groups of at least one rod antenna according to any of the preceding claims, whereby the rod antennas of a group have a beaming direction different than the beaming direction of the rod antennas of the other groups.
In the following description preferred embodiments of the present invention are explained in more detail in relation to the enclosed drawings, in which
a and 5b show a first and a second embodiment of the rod antenna according to the present invention, and
a to 6c show parts of different embodiments of the rod antenna according to the present invention.
In the following, a rod antenna 1 according to the present invention is described. It is to be noted that the present antenna also comprises further features necessary for the functionality of an antenna, e.g. a transceiver, a power supply or the like, which are not explained in the following and not shown in the figures for the sake of clarity.
A metal holder 4 is coupled to the patch 2 and to the rod 5 for transferring said electromagnetic wave between the patch 2 and the rod. The metal holder 4 is coupled to the patch 2 and encompasses the rod 5 partly. The metal holder 4 works as a waveguide and transfers the electromagnetic wave between the three-dimensional rod 5 and the two-dimensional patch 2. In order to achieve a high gain and small sidelobe the height of the metal holder should be equal to the wavelength of the electromagnetic wave or equal to a half of the wavelength of the electromagnetic wave.
The patch 2 hereby serves as a feeding circuit for the rod 5 of the rod antenna 6. With the patch 2 the circuit matching can be controlled.
With the rod antenna 1 according to the present invention the feeding is not limited to the three-dimensional waveguide feeding and any type of feeding can be used. This enables the implementation of the rod antenna into different devices and the antenna 1 can be easily adapted to the requirements of different applications.
In a further embodiment the rod antenna 1 can be used for an antenna array for covering a wide angle of the hemisphere. Herefore, at least two groups of rod antennas 1 are implemented in the antenna array. Each group consists of at least one rod antenna 1 according to the present invention. Further, each group has a beaming direction different from the beaming direction of the other groups. Hereby, the beaming direction is achieved by changing the tilted angle of the rod 5 of the rod antenna 1. With a control circuit then it is possible to change between the different groups for radiating and/or receiving the electromagnetic wave, thereby changing the actual beaming direction in order to cover a wide angle of the hemisphere.
It is to be noted, that the antenna 1 may also comprise a rod 5 without top plane 6.
a shows an embodiment of the rod antenna 1 according to the present invention for linear polarised electromagnetic waves and
As shown in detail in
It is to be noted, that the direction of the feeding line 3 is not limited to the direction of one of the first two coordinate axes but may have any other direction, e.g. the feeding line may be orthogonal to the first two coordinate axes.
The present antenna can be implemented in small consumer products, such as mobile terminals for wireless communication or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05005998.9 | Mar 2005 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2005/013668 | 12/19/2005 | WO | 00 | 10/1/2008 |
