Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
1999-12-22
2001-12-25
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S7000MS
Reexamination Certificate
active
06333716
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an antenna for a handset. The antenna includes a metallic plate or layer acting as ground plane for the antenna, a resonator plate or layer acting as radiating element(s), and a feeding point supplying the signal to the antenna. When the ground plane and the resonator plane are electrically coupled the feeding point will be placed in a position where the antenna is matched to the RF output of the handset. Such antennas are known as Plannar Inverted F-Antennas (PIFA).
Until a few year ago all phones for cellular communication were equipped with an extendable antenna element, as known from e.g. the phone sold under the tradename Nokia 2110™. Later on this extendable antenna element were substituted by an external helix antenna, as known from e.g. the phone sold under the tradename Nokia 6110™. Recently the applicant has launched a phone sold under the tradename Nokia 8810™ and this phone includes an internal antenna based on the PIFA concept. The antenna is a so-called single band antenna and the present version it is adapted for GSM in the 900 MHz band (uplink 890-915 MHz and downlink 935-960 MHz). The antenna element will have an electric length corresponding to a quarter wavelength and placing a dielectric between the ground a resonator plane the over physical dimensions is reduced. The overall dimensions of the PIFA are reduced to 32×20×4 mm.
WO 95/24746 describes an internal antenna having a dielectric body coated with a metallic layer on two substantially parallel surfaces. This antenna is a single band antenna for the GSM 900 MHz band only. Basically a plastic body is molded and with metal. Afterwards a pattern is created in the metallic layer by removing parts of the coated surfaces by milling. This concept has been used in the phone marketed by Hagenuk under the tradename Global Handy™.
U.S. Pat. No. 5.764.190 describes a capacity loaded PIFA according to which an extra plate is interposed in between the ground plane and the radiating element. This requires that a two-shot moulding process is used in addition to several coating processes.
A letter by C. R. Rowell and R. D. Murch, “A Compact PIFA suitable for dual frequency 900/1800 MHz operation”, is published in IEEE Transactions on Antennas and Propagation, April 1998, Volume 46, Number 4. This letter is written by the inventors mentioned in U.S. Pat. No. 5.764.190, and describes further improvement of the three layered antenna concept. The improvement includes providing of a longitudinal slit in the resonator layer in order to obtain two radiating elements. The RF signal is fed to the radiating elements via the intermediate plate.
A letter by Z. D. Lui and P. S. Hall, “Dual-Frequency Planar Inverted-F Antenna”, is published in IEEE Transactions on Antennas and Propagation, October 1997, Volume 45, Number 10. This letter describes a number of solutions—one of these having a rectangular patch for the 900 MHz band. This patch is provided with a L-shaped slot separating one quarter of the 900 MHz band for acting as resonating element in 1800 MHz band. The two resonating elements are interconnected in the bottom of the slot the common feeding point is provided in this interconnection. Furthermore the two resonating elements are shortened in this interconnection by means of a number of shorting pins. Hereby the coupling between the two radiating elements is reduced.
An object of the invention is to provide an antenna for a handset having a form that can be integrated into the per se known handset cabinets. This antenna must be easy to manufacture without the requirement of manual labouring steps.
SUMMARY OF THE INVENTION
This purpose is obtained by the method for manufacturing an antenna body part according to the invention. This purpose is obtained by the method for manufacturing an antenna device according to the invention. A method for manufacturing an antenna device for a radio telephone, comprising steps of providing an antenna body part by forming a first part of the dielectric body by injection molding where a first resin is injected into a first cavity in the injection molding tool, by forming a composite dielectric body by injection molding where a second resin injected into a second cavity in the injection molding tool, said first part of the dielectric body is placed in the second cavity as a core for becoming an integrated part of the composite body, and by coating a metallic layer onto the surface of the composite dielectric body where said first and second resins are selected to have different adhesive properties for the metal coating so one of the resins repels the metallic layer while the other allows the metallic layer to adhere. Finally the antenna body is mounted on a separate metal body acting as ground plane for the antenna body. Hereby the radiating metallic pattern is obtained without using any mask or manually removing of exceeding metallic layer. Actually the antenna body may be handled and any other of the plastic covers of the phone with regard to injection molding. The plating process may be a standard process without any mechanical step as drilling or milling.
Both resins are selected as being crystalline polymer synthesized from styrene monomer, and one of the resins is provided as a compound with an added catalyst. Hereby the final antenna body will have homogeneous properties and may be manufactured by a standard injection molding process.
The invention furthermore relates to antenna body part for use in an antenna device using a separate metal shield as ground plane. This antenna body part has a dielectric body, and a first conducting layer acting as resonator plane coated as a pattern covering a part of the dielectric body. This dielectric body is provided by a two shots injection molding process including, wherein the material used in a first shot is a resin repelling metal in a subsequent coating process, and wherein the material used in the second shot is a resin to which metal in the subsequent coating process adhere. The manufacturing process may hereby be a standard two-shot injection molding procedure followed a electroless metallisation process, e.g. a dip plating process, and therefore only requires a very low amount of manual labouring time.
Preferably the dielectric body is snapped onto the metallic shield acting as ground plane for the antenna. Hereby the shield and the antenna may be handled as one unit during the assembly of the phone.
By providing the antenna device with a through going bore through the dielectric body a resilient connector on the PCB extending through the shield may be used for feeding the antenna via the connection pad on the rear side of the dielectric body.
A major purpose of the antenna device according to the invention is to provide an antenna device to be used as in internal antenna for a phone or a handset.
REFERENCES:
patent: 5260394 (1993-11-01), Tazaki et al.
patent: 5407622 (1995-04-01), Cleveland et al.
patent: 5764190 (1998-06-01), Murch et al.
patent: 6040803 (2000-03-01), Spall
patent: 6097339 (2000-08-01), Filipovic et al.
patent: 6110576 (2000-08-01), Decker et al.
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patent: 0997968A1 (2000-05-01), None
patent: 2171355 (1986-08-01), None
patent: 2288284 (1995-10-01), None
patent: WO95/24746 (1995-09-01), None
patent: WO99/35708 (1999-07-01), None
A Capacitively Loaded PIFA For Compact Mobile Telephone Handsets, EPO, May 5, 1997, 3 p.p..
Dual-Frequency Planar Inverted-F Antenna, EPO, 10, 10, 1997, 4 p.p..
A Compact PIFA Suitable for Dual-Frequency 900/1800-MHz Operation, EPO, Apr. 4, 1998, 4 p.p..
Patent Abstracts of Japan, 62023603, 31.01.87, 1p..
Patent Abstracts of Japan, 02307716, 20.12.90, 1p..
C. Rowell, et al, A compact PIFA Suitable for Dual-Frequency 900 Transactions on Antennas and Propagation, vol. 46, No. 4, Apr.
Nguyen Hoang
Nokia Mobile Limited
Wong Don
LandOfFree
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