GB2356085A

GB2356085A - Dual frequency mobile 'phone antenna

Info

Publication number: GB2356085A
Application number: GB9925941A
Authority: GB
Inventors: Daniel Chang
Original assignee: Auden Techno Corp
Current assignee: Auden Techno Corp
Priority date: 1999-11-03
Filing date: 1999-11-03
Publication date: 2001-05-09
Also published as: GB9925941D0

Abstract

A dual frequency mobile 'phone antenna comprises a helical induction coil 30 and a thin metal sheet 50 arranged by the coil so as to define the antenna's operating frequencies. The coil is supported on a column 20 mounted inside a cylindrical body 92 carrying the metal sheet on its outer surface 98 where the upper portion of the cylindrical body is covered by a clip-on cap 91 and the lower portion is adapted for mounting on a mobile 'phone. The signal is fed to the coil through a flexible metal member 40 which is mounted through the cylindrical body, so as to contact the coil, and which protrudes 41 from the lower portion of the cylindrical body to contact the mobile 'phone circuitry. The metal sheet may be fixed to the cylindrical body using a sticky coating applied to the sheet.

Description

2356085 TITLE: MOVABLE ANTENNA STRUCTURE WITH TWO FREQUENCIES FOR

COMMUNICATION

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention is related to a movable antenna structure with.two frequencies for communication, especially to one suiting mobile phones and being convenient for manufacturing and assembling.

2. Description of the Prior Art

In conventional mobile phones, an antenna used only for a single frequency can only be availabl e for two different telephone frequencies when it is used with a frequency matching device.

The antennas with two frequencies used nowadays generally can be chosen from various coils with different diameters which are mutually matchable or metallic conductive sheets in the shapes of wave forms used in lieu of coils. Fig. I and 2 show such a metallic conductive sheet 10 as an antenna with two frequencies. Wherein, the conductive sheet 10 is punching formed with a thin metallic sheet, and includes generally an end vertical section I I with a shape of wave form and a horizontal section 12 with another shape of wave form. The metallic conductive sheet 10 is a flat conductor with a specific width when in punching forming (as shown in Fig. 2); it can be fittingly wrapped around an interior column 13 of the antenna.

Such conventional structure of antennas with two frequencies must use the vertical section I I and the horizontal section 12 integrally connected with each other and both made of thin sheet material. Therefore, precise die is required to form the whole conductive sheet 10 by punching and thus costs higher. And the planar metallic thin sheet 10 must be fittingly wrapped I around the interior column 13 of the antenna; it is more bothersome and cumbersome in production. And more, in using such a structure of antenna with two frequencies, the original procedure of process must be changed, and reopening of a mold is requisite, thus working hours of production and assembling will be increased and cost will be largely increased.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a movable antenna structure with two frequencies for communication; wherein, the interior hollow column of an electric induction coil is fittingly wrapped around by a metallic thin sheet with its frequency matching with that of the coil. One side of the metallic thin sheet is a sticky surface and can be stuck directly on the interior hollow colunm to form the antenna structure with two frequencies.

The metallic thin sheet not only can be easily made, but can also be conveniently assembled in the antenna. The complicated processing procedure as well as higher cost of production for the existing antenna structure with two frequencies can thus be saved and reduced, and this is the motive of the present invention.

The present invention will be apparent after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Fig. I is a perspective view showing a conventional structure of antenna Fig. 2 shows the metallic conductive sheet of Fig. I in a stretching state; Fig. 3 is a perspective view showing an embodiment of the present 2 invention; Fig. 4 is a schematic view showing the structure of Fig. 3 with a cap being removed; Fig. 5 is a schematic view showing the structure of Fig. 4 with a coil 5 being removed; Fig. 6 is an analytic perspective view according to Fig. 3; Fig. 7 is a sectional view taken from Fig. 3; Fig. 8 is a sectional view taken from line 8-8 in Fig. 7; Fig. 9 is a sectional view taken from line 9-9 in Fig. 7; Fig. 10 is a chart showing frequency test on the real product of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to Fig. 3 and 4, a movable antenna 90 with two frequencies for communication on a mobile phone generally is comprised of a cap 91 with a specific length and fitting over the body of the antenna 90, and an inner cylinder 92 together with its insertion portion 93 exposed to the area below the cap 9 1.

The basic structure of the present invention is shown in Fig. 4-6, wherein, the inner cylinder 92 is provided in a hollow interior thereof with a plurality of main elements including a positioning column 20, an electric induction coil 30 and an elastic contact piece 40. The positioning column 20 is provided with a top supporting-seat 21 for positioning the bottom end of the electric induction coil 30. The electric induction coil 30 can thereby be positioned with a specific upright length in the inner hole 94 of the inner cylinder 92. The contact piece 40 is provided with a straight section of suitable length capable of extending into the inner cylinder 92 to press 3 contact the electric induction coil 30, and with an exposing curved section 41 exposed to the exterior of a slot 95 on the bottom of the inner cylinder 92 and in a direction parallel to the axis of the inner cylinder 92. The antenna 90 thereby can be inserted into a hole (not shown) on the top of the mobile phone. The exposing curved section 41 makes an elastic and electric conductive connection with the mobile phone.

In the preferred connecting state as shown in Fig. 6 and 7, the positioning column 20 has a tapered section 22 of suitable size in order to let the positioning column 20 be pressed through a through hole 96 provided in the inner cylinder 92 into a proper position. The cap 91 is provided with an inner flange 97 matchably snap engaged with an exterior flange 99 opposite thereto on the exterior periphery 98 of the inner cylinder 92. So that the induction coil 30 is pressed with one end thereof against the top supporting seat 21 of the positioning column 20, while the other end thereof against the inner top surface of the cap 9 1.

The main point of the present invention is a metallic thin sheet 50 of suitable area on the exterior periphery 98 of the inner cylinder 92 at the position corresponding to that of the induction coil 30. The metallic thin sheet 50 is made of suitable metal such as copper and has an extremely small thickness, the metallic thin sheet 50 is made a sticky sheet with suitable flexibility and can be stuck directly and matchably on the surface of the exterior periphery 98.

In the preferred embodiment, the metallic thin sheet 50 can be suitably dealt with coating process; the inner surface thereof is made sticky. The metallic thin sheet 50 thereby can be stuck directly on the exterior periphery 98 of the inner cylinder 92 at a desired position. The metallic thin sheet 50 is 4 positioned between the inner surface of the cap 91 and the exterior periphery 98 of the inner cylinder 92 and is juxtaposed to the position of the induction coil 30 (referring to Fig. 7 and 8).

Selection of the above stated induction coil 30 and metallic thin sheet 50 can be done in pursuance of the following formula:

Assuming the match frequency of both the induction coil 30 and metallic 1 thin sheet 5 0 is fo, then fo = 2 74L-C, wherein, L is the value of electric induction C is the value of capacity.

By virtue that electric induction impedance ZL = jWLO 1, w 2 Xf) while capacity impedance Zc jwC to match the two values, Z L + ZC 01 I i.e., jwL + jwC = 0 - WL + 0 WC -w 2 L+ I = 0 C w 2 = 1 LC 1 W -JL-C A 2 7r-AL-C Put the value obtained from testing for the coil and the metallic sheet into the above listed formula of match frequency, we can obtain the desire coil and the metallic sheet with two frequencies.

Fig. 10 shows a chart showing frequency test on the real product with such structure of the present invention. Wherein, the frequency of the first point is 8 90NEFIZ, that of the second point is 960MHZ, the third point is 17 10 N4HZ, and the fourth point is 1880 MHZ, while the VSVvTR value is less than 2 for all of them, the product is quite excellent functionally.

In order to be available for coils with different values of electric induction, the above stated metallic thin sheet can be of various sizes and areas, so that it can be fittingly stuck on an antenna structure with semicircular curved shape or one of any other different curved shapes.

By virtue that the present invention can produce the metallic thin sticker sheet by a very easy way without using any of the above mentioned conductive sheet structures formed by punching in the antennas with two frequencies. And especially, the present invention can be assembled very fast and conveniently by sticking the metallic sheet on the periphery of the inner cylinder. Thereby, an antenna structure with two frequencies can be made without changing any of the original processes in manufacturing an antenna with single frequency. It is really industrial valuable.

My invention may assume numerous forms and is to be construed as including all modifications and variations falling within the scope of the appended claims.

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Claims

1. A movable antenna structure with two frequencies for communication, comprised of a cap and an inner cylinder with its exposed insertion portion being inserted into a communication device, wherein, said inner cylinder is provided in a hollow interior thereof with a positioning column positioning an electric induction coil being covered by said cap, and with an elastic contact piece making an elastic and electric conductive connection with said communication device, said antenna structure is characterized by that:

a metallic thin sheet is provided on the exterior periphery of said inner cylinder at the position corresponding to that of said induction coil, said metallic thin sheet is located between the inner periphery of said cap and the exterior periphery of said inner cylinder, and is juxtaposed to the position of said induction coil to get match frequency.

2. A movable antenna structure with two frequencies for communication as in claim 1, wherein, the exterior surface of said metallic thin sheet is dealt with coating process, and the inner surface thereof is made sticky to be stuck directly on the exterior periphery of said inner cylinder.

3. A movable antenna structure with two frequencies for communication as in claim 1, wherein, said metallic thin sheet is of any of various sizes and areas in corresponding to those of said coil.

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