Communications: radio wave antennas – Antennas – Measuring signal energy
Reexamination Certificate
2001-06-27
2002-10-22
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
Measuring signal energy
C343S7000MS, C343S702000
Reexamination Certificate
active
06469673
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The invention concerns generally the technological field of planar antenna arrangements in portable radio devices. Especially but not exclusively the invention concern s inverted-F antenna arrangements. The invention also concerns a portable radio device equipped with such a planar antenna arrangement. And, additionally the invention concerns a method for assembling and testing a portable radio device comprising a planar antenna.
BACKGROUND ART OF THE INVENTION
Low profile antennas such as planar antennas are well known in the art. One of the known and widely applicable planar antenna solutions used in mobile telephones is the PIFA or Planar Inverted F Antenna. It consists of a planar conductive sheet (that may have a smooth outer contour or comprise various cuts) that acts as a radiator, and a planar conductive ground surface which is essentially parallel to the radiator. The surfaces need not be exactly planar, and they need not be exactly parallel to each other. There are one or a few conductive connections between the radiator and the ground surface, usually implemented as conductive pins or strips that are essentially perpendicular to the direction of the planar surfaces. A feeding pin or a feeding strip coupled to a certain feeding point of the planar radiator serves to couple the antenna to the antenna port of a radio device.
An example of an inverted-F antenna is shown in
FIG. 1
of the accompanying drawings. The antenna
10
comprises a feed section
12
coupled to a short circuited inductive stub
14
and a capacitive line
16
. The inductive stub
14
is short circuited to a ground plane
18
, above which the feed section
12
protrudes by a distance D. The ground plane
18
is open to allow access for the feed section
12
which is electrically isolated from
11
from the ground plane
18
. The respective lengths L
1
, L
2
, of the inductive stub
14
and the capacitive line
16
are determined to give a desired resonanc e frequency and input impedance Z
in
seen from the antenna feed point
12
. The input impedance is dependant upon the position of the feed section
12
and hence the lengths L
1
and L
2
, a nd can be made substantially resistive. Further details regarding inverted-L or -F antennas may be found in “Small Antennas” ISBN 0863 80 048 3, pages 1116-151.
Inverted F-antenna s have found particular applications in the portable radio devices, and especially mobile telephones where their high gain and omni-directional radiation patterns are particularly suitable. They are also suitable in applications where good frequency selectivity is required. Additionally, since the antennas are relatively small at typical radio telephone frequencies they can be incorporated within the housing of a radio telephone thereby not interfering with the overall aesthetic appeal of the radio telephone and giving it a more attractive appearance than radio telephones having external antennas. By placing the antenna inside the housing of a radio telephone, the antenna is also less likely to be damaged and therefore have a longer life time. The ground plane of an inverted-F antenna can be made on a printed wired board, and thus the inverted-F antenna lends itself to planar fabrication on printed wired board typically used in radio telephones.
FIG. 2
illustrates a known PIFA construction and its use in a mobile telephone, which in
FIG. 1
is seen in an opened position so that its keypad, display, microphone and loudspeaker which are located on the distant side of the right-hand part are not seen. The functional parts of the mobile telephone
201
have been constructed onto a printed wired board or PWB
202
. The PWB with all the components attached thereto has been enclosed into an outer cover
203
which consists of two halves
203
a
and
203
b
and also serves as a support structure. The PWB
202
is attached to the front half
203
a
of the outer cover. At the top end of the PWB
202
there is an antenna feeding pad
204
and a ground plane
205
which are parts of the conductive structures formed on the planar surface of the PWB. In most mobile telephones and other small radio devices the PWB is of the multilayer type in which case the ground plane
205
could be also located at one of the inner layers.
At the top end of the inside of the cover there is a conductive radiator
206
. A feeding pin
207
and a grounding pin
208
protrude from the conductive radiator
206
into a direction which is towards the PWB
202
when the parts
206
,
103
a
and
103
b
are attached together. When the cover is closed, the conductive radiator
206
and the ground plane
205
come into a parallel configuration and the feeding pin
207
and grounding pin
208
touch the antenna feeding pad
204
and ground plane
205
respectively, so a PIFA antenna is produced. The back cover
203
b
must be electrically non-conductive at least at its top end where the conductive radiator
206
is located.
Despite the small size of planar antennas, the fact that radio telephones are becoming smaller and smaller and more complex necessitating a greater amount of electronics within the housing, the space available for the inverted-F antenna is getting smaller and it is more difficult to conviniently fit such antennas into the housing.
Another problem with using an inverted-F antenna is related to manufacturing and especially testing the radio device. The testing phase of a radio telephone normally comprises alignment and galvanically measured tests of the RF electronics. This is normally made before the antenna is assembled by connecting an RF test probe in contact points of the antenna. After this phase of testing the RF test probe is disconnected and the antenna is assembled and connected in place. Finally, the function of the antenna is tested using a coupler. In a mass production of radio devices such as radio telephones it is advatageous to use automated assembling and testing. Therefore it is a drawback that the RF electronics and the antenna must be tested separately having an assembly phase between the test phases. Therefore, in an automated manufacturing the radio telephone should be first placed on an automated assembly line for assembling the electronics, then on an automated testing bench for testing the (RF) electronics, and after testing the electronics the equipment should be placed on a next assembly line for assembling the antenna, and finally the equipment should be again placed on a test bench for testing the antenna. Having so many assembling/testing phases causes additional time and costs for the manufacturing of radio telephones.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a planar antenna structure with which the disadvantages of prior art solutions would be reduced or avoided. It is especially an object of the present invention that the antenna structure is applicable to large scale mass production of radio devices, including testing.
One idea of the present invention is providing an aperture in the radiator plate of the planar antenna. An RF test point is provided for aligning the RF electronics and the RF test point is located in such a way related to the aperture of the radiator that the test signal is easily led through the aperture. It is further advantageous that an RF switch is provided for coupling/decoupling a connection between the planar antenna and the RF electronics. In a preferred embodiment the RF switch is integrated with the RF test point. The inventive arrangement thus allows testing the RF electronics after the radiator plate has been attached to the PWB.
The present invention has important advantages over the prior art. The tuning and testing of the radio device can be made with a single automatic arrangement, and it is necessary to attach the device to the test bench just once. It is also possible to make the automatic assembly work on a single line before the testing/tuning procedure; It is not necessary to make any substantial assembly work after the testing/tuning procedure. As a result, it is
Nokia Mobile Phones Ltd.
Perman & Green LLP
Wimer Michael C.
LandOfFree
Antenna circuit arrangement and testing method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Antenna circuit arrangement and testing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Antenna circuit arrangement and testing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2924432