Communications: radio wave antennas – Antennas – Active sleeve surrounds feed line
Reexamination Certificate
1999-06-23
2001-04-24
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Active sleeve surrounds feed line
C343S792000, C343S795000, C343S727000
Reexamination Certificate
active
06222494
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority of European Patent Application No. 98305164.0, which was filed on Jun. 30, 1998.
FIELD OF THE INVENTION
The present invention relates to a delay line, and particularly but not exclusively to a feeding delay line in a collinear antenna array.
BACKGROUND OF THE INVENTION
In a wireless local area network (WLAN) a number of wireless access points (APs) form the wireless infrastructure, and wireless hosts communicate with each other via the wireless APs. The wireless hosts may be stationary or may roam around. Such a system is similar to any cellular network system.
A requirement for antennas at a wireless access point, or in a base station of a cellular network, is that the radiation must be omni-directional in the azimuth plane, in order to give an equal chance of access to all mobiles around it. There is a continuing desire for higher gain, omni-directional antennas, in particular for wireless APs, so as to extend the cell size in a cellular network and/or increase communication reliability of cells. However, such improvements need to be achieved whilst minimizing the cost, size and technical complexity of the antennas.
A good example of an omni-directional antenna is the well-known half wavelength dipole antenna which has a so-called “donut” shaped radiation pattern providing good omni-directional coverage. Such well-known half-wavelength dipole antenna's have a signal gain of 2 dBi, which can be insufficient for the desired large cell size/good communication reliability required or wireless AP antennas. A gain of 5 dBi can provide substantial improvements in omni-directional coverage.
The 2 dBi gain of a half-wavelength dipole antenna can be increased by “squashing” the “donut” radiation pattern across its vertical cross-section, thus changing it from the “donut” shape of a well-known half-wavelength dipole antenna to a “squashed donut”, being flatter and larger in the azimuth plane.
Theoretically, such a pattern modification can be obtained, for example, by means of a couple of ordinary half-wavelength dipoles vertically stacked on top of each other to form a collinear array and fed in phase. However, the implementation of such an antenna can be troublesome primarily due to difficulties in arranging the feeding for the array elements in such a way as to avoid disturbing the radiation pattern. Known solutions to the problem of providing a feeding network in the collinear array add to the cost, size, or technical complexity of the antenna, which is undesirable.
It is therefore an object of the present invention to provide a feeding arrangement suitable for use in a collinear array antenna which can be implemented in a collinear array without unduly increasing the technical complexity thereof, which minimizes interference with the radiation pattern of the antenna, and which does not unduly add to the physical size of the antenna.
SUMMARY OF THE INVENTION
Thus, in one aspect of the present invention there is provided a delay line formed on an insulating sheet and having an input and an output, and comprising a single spiral revolution conductive strip coupled between the input and output.
There is thus provided a compact delay line suitable for use in an antenna array feeder stage.
The single spiral revolution conductive strip may comprise in one preferable embodiment: first to fifth conductive strips connected end-to-end in series, the first and third conductive strips being opposite to one another, the third and fifth conductive strips being opposite to one another and the second and fourth conductive strips being opposite to one another. Preferably the first and third conductive strips are parallel, the third and fourth conductive strips are parallel, and the second and fourth conductive strips are parallel.
The end of the first conductive strip not connected to the second conductive strip may be connected to the input by a sixth conductive strip. The end of the fifth conductive strip not connected to the fourth conductive strip may be connected to the output by a seventh conductive strip.
The single spiral revolution strip may comprise in another preferable embodiment: a first conductive strip coupled at one end to the input; a second conductive strip connected at one end to the other end of the first conductive strip and orientated at approximately 90° thereto; a third conductive strip connected at one end to the other end of the second conductive strip and orientated at approximately 90° thereto in a direction opposite to that of the first conductive strip: a fourth conductive strip connected at one end to the other end of the third conductive strip and orientated at approximately 90° thereto in a direction opposite to that of the second conductive strip; and a fifth conductive strip connected at one end to the other end of the fourth conductive strip and orientated at approximately 90° thereto in a direction opposite to that of the third conductive strip, and coupled at the other end thereof to the output.
The first conductive strip may be coupled to the input by a sixth conductive strip connected at one end to the other end of the first conductive strip and orientated at approximately 90° thereto in a direction opposite to that of the second conductive strip. The fifth conductive strip may be coupled to the output by a seventh conductive strip connected at one end to the other end of the fifth conductive strip and at its other end to the output, and orientated at approximately 90° relative to the fifth conductive strip in a direction opposite to the fourth conductive strip.
The first to sixth conductive strips are preferably formed on a first side of the insulating sheet, and the seventh conductive strip (
50
) is preferably formed on a second side of the insulating sheet.
Preferably, the third conductive strip is longer than the first conductive strip, the fourth conductive strip is shorter than the second conductive strip, the fifth conductive strip is shorter than the third (
44
) conductive strip, and the output is located opposite the input (
34
).
The present invention further provides an antenna array comprising at least one feeder stage including a single spiral revolution conductive strip delay line.
In another aspect of the present invention there is provided a collinear antenna array formed on an insulating sheet comprising: a first end fed dipole antenna system for a radio frequency generator having an operating wavelength L, comprising: on a first side of an insulating sheet a first and a second quarter wavelength conductive strip in end-to-end connection; on a second side of the insulating sheet a third quarter wavelength conductive strip, overlying the first quarter wavelength conductive strip, a fourth quarter wavelength conductive strip having a longer arm spaced from and parallel to the third quarter wavelength conductive strip and a shorter arm connected to the third quarter wavelength conductive strip and a fifth quarter wavelength conductive strip having a longer arm spaced from and parallel to the third quarter wavelength conductive strip, symmetrical with the fourth quarter wavelength conductive strip, and a shorter arm connected to the third quarter wavelength conductive strip; and means to connect said radio frequency generator between the end of the third quarter wavelength conductive strip remote from the connection to the fourth quarter wavelength conductive strip, and the corresponding end of the first quarter wavelength conductive strip, whereby the second and fourth quarter wavelength conductive strips form a linear dipole antenna; wherein the collinear antenna array further comprises; a feeder stage including a delay line having an input and an output and a single spiral revolution conductive strip coupled therebetween, the delay line input being connected to the end of the second quarter wavelength conductive strip remote from the first quarter wavelength conductive strip; and a monopole comprising a conductive strip having one end connected to the output of the
Agere Systems Guardian Corp.
Le Hoang-anh
LandOfFree
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