WO2001003236A1

WO2001003236A1 - Antenna arrangement and method

Info

Publication number: WO2001003236A1
Application number: PCT/SE2000/001413
Authority: WO
Inventors: Tony BJÖRKMAN; Jari Paananen
Original assignee: Avantego Ab
Priority date: 1999-07-01
Filing date: 2000-07-03
Publication date: 2001-01-11
Also published as: AU6041700A

Abstract

The present invention relates to a non-quadrifilar antenna arrangement (10) in a communications apparatus (8) for single, dual and/or multi-band frequency including at least one antenna element (12a-12i, 12b-12j) arranged on at least one surface of a substantially flexible substrate (11) essentially entirely and continuously on said substrate (11) and shaped to a helix. The helix has a first and a second end, said first end being one end of said antenna element at one portion connected to one feeding line and said second end being free radiating.

Description

TITLE

ANTENNA ARRANGEMENT AND METHOD

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an antenna arrangement for transmission and/or reception of electromagnetic radiation, and specially to an antenna arrangement for single, dual and/or multi-band frequencies.

The invention also concerns a method for manufacturing the antenna arrangement.

BACKGROUND OF THE INVENTION AND RELATED ART

The wireless forms of communications have become a standard way of communication. There are many types of means for conducting a wireless communication, such as cordless telephones, lap top computers with wireless modems, satellite and cellular telephones.

The communication device, i.e. the mobile handsets rapidly become smaller and lighter and the globalization demand, multiple communication functions and standards being combined into a single unit, e.g. for communicates in multiple frequency bands.

There are a variety of different radiotelephone systems in use today. These include different analogue or digital CDMA (Code Division Multiple Access) and TDMA (Time Division Multiple Access) based systems like GSM (Global System for Mobile telecommunication), AMPS (Advanced Mobile Phone System), DAMPS(Digital Advanced Mobile Phone System), PCS (Personal Communication Services), DCS (Digital Communication System) PCN (Personal Communication Networks ), PDC 800 and 1500 and different cordless telephone systems.

Different systems operate in different frequency bands, thus requiring different antennas for maximum efficiency.

US 5,668,559 concerns an antenna for portable radio devices including a helical antenna coupled at the base to a transmitter/receiver. The pitch of a conductive material helix constituting the helical antenna varies according to the height of the helix. It decreases from the base of the helical antenna towards its top. The antenna comprises a helical antenna and a retractable whip. The helical antenna comprises deposited metal onto a flat and flexible insulative film, whose shape is the developed shape of the final shape required for the helical antenna. The entire antenna is not produced on the one film but on joining together the opposite edges of the film. For this purpose the film incorporates metal vias and metalized lands around the vias on the side opposite that carrying the pattern to provide electrical continuity. The film is welded to a former of the required shape.

The major drawback with the known antennas for different frequencies is that they have problems either with the bandwidth, size or efficiency.

In US 3,573,840, a small bulk cylindrical or conical antenna made of a helically wound conductor with a free end and a grounded end is described. The coupling to a power supply or a load circuit is effected along a short length of said conductor near to and terminating on said ground plane, either by direct shunt coupling or by inductive coupling. The grounded end can be provided with a capacitive load. The antennae can be manufactured by sticking a metal strip to a dielectric sheet and rolling the latter to the desired shape, or by printing circuit technique and subsequent winding to said shape, in which they may be kept by clamping, glueing or any other method.

WO 98/28814 discloses an antenna operable in two disparate frequency bands, including a first quadrifilar helix having four conductive elements arranged helically to define a cylinder of substantially constant radius, where the first quadrifilar helix is formed of two bifilar helices arranged orthogonally and excited in phase quadrature. A quadrature feed network is connected to the first quadrifilar helix, wherein one end of a coupling element thereof is connected to a first end of each conductive element. The quadrature feed network also includes a first feedpoint for operation of the antenna with circular polarization in a first frequency band and a second feedpoint for operation of the antenna with linear polarization in a second frequency band. The antenna may include a second quadrifilar helix connected to the quadrature feed network and having four conductive elements arranged helically to define a cylinder of substantially constant radius, where the second quadrifilar helix is formed by two bifilar helices arranged orthogonally and excited in phase quadrature. The second quadrifilar helix is wound in opposite sense with respect to the first quadrifilar helix so as to be conductively coupled therewith.

Moreover, US 5,134,422 describes a quadrifilar helical type of antenna, which has at least one radiating cord, helically wound in a rotational shape. The antenna has a circuit for the supply of the radiating cords formed by a strip line type of transmission line which fulfills both the supply distribution function and the function of matching the radiating cords of the antenna.

SUMMARY OF THE INVENTION

The main objective with the present invention is to overcome the drawbacks inherited from the known antennas, and to provide a non-quadrifilar antenna with enhanced band width while the size and the efficiency are maintained or rather improved.

Yet another object of the present invention is to avoid the traditional coil winding and thereby avoid the resulting geometrical and tolerance limitations.

There is also a need for a light and less costly single, dual and/or multi-band antenna arrangement, which allows operation of a single communication device in multiple frequency bands.

Moreover, the antenna arrangement according to the present invention provides for optimization of impedance match, large bandwidth and high efficiency.

For these reasons, the initially described antenna arrangement includes at least one antenna element provided on at least one surface of a substantially flexible substrate. The antenna element is arranged essentially entirely and continuously on the substrate.

In one advantageous embodiment the antenna element is arranged partly in a diagonal direction of said flexible substrate.

In another preferred embodiment said antenna element is arranged partly in a diagonal direction of said flexible substrate having an originating point in a middle section of said substrate. In another embodiment a branching constituting a second antenna element is arranged.

Preferably, the antenna element comprises at least one geometrical shape with varying size. The antenna element may also be curved.

Advantageously, the antenna element has at least one signal feeding line on at least one corner section of said substantially flexible substrate.

For different purposes said antenna element is arranged in said diagonal direction at least in one first angel and one second angel relative at least one edge of said substantially flexible substrate.

For the different bandwidth applications, the antenna arrangement comprises a first antenna element having a first length and a second antenna element having a second length.

Preferably, the antenna elements may be arranged on opposites surfaces of the substrate and have feeding points at opposite corners of the substrate.

Preferably, the substrate is deformed and arranged on, inside or embedded in a carrier and advantageously it forms a helix antenna. The carrier may be a casing of the communication apparatus. The antenna arrangement may also cooperate with a whip antenna.

To control the thickness and/or capacitive coupling of the elements the substrate may be arranged with at least one recess.

According to a method for manufacturing an antenna arrangement for single, dual and/or multi- band frequency including at least one antenna element essentially entirely and continuously arranged on at least one surface of a substantially flexible substrate; the method comprises the steps of: cutting out pieces of substrate in suitable sizes with at least one defined edge; applying metal strip(s) using an appropriate metalization method with respect to said defined edge as reference point; and an additional step of arranging the antenna device comprising the substrate and antenna elements on or inside a carrier for producing a helix antenna, if such an antenna is needed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in more detail and in a non-limiting way with reference to the accompanying drawings in which:

Fig. 1 is a schematic illustration of a communication device in perspective, Fig. 2 is a schematic elevation view of an antenna device according to the present invention, Fig. 3 illustrates in a schematic way the antenna device according to fig. 2 wounded on a carrier, and

Figs. 4-9 show additional embodiments of the antenna device according to the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The communication device 8 according to fig. 1, e.g. a mobile station in a cellular communications system such as GSM, is known per se. However, it is arranged with an antenna arrangement 10', preferably arranged inside a cover 9. The antenna arrangement 10 is connected to the transmitting and receiving sections of the communication device according to known technique.

The main distinguishing features between the antenna device according to the present invention & and the prior art is that an antenna element is essentially entirely and continuously deposited on a single substrate. Moreover, a number of antenna elements for dual and multi-bands can be arranged on a single substrate.

Fig. 2 illustrates the first embodiment according to the present invention. The antenna device 10 comprises a supporting element 11 , preferably a flexible substrate, a first and a second antenna elements 12a, 12b and a feeding line 13. The substrate consists of a suitable dielectric film, which allows folding or winding. The antenna elements 12a and 12b are conductive metallic strips deposited onto the substrate in a suitable metal deposition way, such as silkscreen printing, photolithography or the like. The feeding line 13 is preferably part of the antenna elements or a conductive strip connected to the elements and the transmitter/receiver of the communication device (or other antennas). The antenna according to this embodiment is intended for a dual band application, and therefore it comprises two elements 12a and 12b with different electrical lengths. For a single band antenna only one antenna element is required.

Preferably the substrate has a rectangular shape. For clarity reasons, in the following one long edge of the substrate is defined as a main edge and denoted with 15, from which the antenna elements extend; Any edge of the rectangle may however be defined as the main edge. Preferably, the antenna elements are arranged along the diagonal direction of the substrate, substantially in parallel, having one end connected to the feeding line 13 arranged on one corner section of the substrate at the said main edge and extend towards an opposite corner section. In one embodiment the elements can be arranged on either side of the substrate or extend towards each other from opposite corners (on the same or different faces of the substrate).

Fig. 3 illustrates the antenna arrangement 10', e.g. for a mobile telephone device according to fig. 1. The antenna arrangement 10' comprises the antenna device 10 according to fig. 2 wounded on a substantially cylindrical carrier 14, which can be mounted on the telephone 10. The carrier may consist of a plastic cylinder or the like. When the antenna device is wounded into a substantially cylindrical form, a helix antenna is obtained. It is possible to produce different forms of helixes with different pitches by varying the length or the inclination (e.g. with respect to the main edge of the substrate) of each antenna element. The antenna device may also be arranged inside the carrier. The substrate may be provided with an adhesive on one surface to simplify the winding.

The antenna elements do not need to be entirely straight as shown in fig. 2. Fig 4 illustrates an antenna device 10 in which the antenna elements 12c, 12d extend in varying directions and have different inclination angles α, β, α' and β' (e.g. with respect to the main edge). One advantage with the variable geometrical appearance of the elements is that the antenna device does not need to be limited to cylindrical carriers and carriers with other cross-sectional shapes, e.g. circular, square, hexagonal etc. can be used, whereby the form of the elements can compensate for the form of the carrier. For example the antenna may be arranged on, inside or embedded in the casing of the telephone. Preferably, some part of the substrate can be removed to provide a thin helix (see for example the lower edge of the substrate). It also provides a way for controlling the capacitive coupling of the antenna element. The capacitive coupling may also be controlled through, e.g. different substrate materials, its thickness and the width of the conductive strips.

Another embodiment is illustrated in fig. 5, in which the elements 12e, 12f extend from the center section of the main edge of the substrate 11 in opposite directions. The elements 12e, 12f have different lengths for different frequency bands.

In the embodiment according to fig. 6, the first antenna element 12g is fed from a feeding point 13' not situated on the edge of the substrate 10. The first antenna element 12g branches off into a second element 12h along its length.

A further embodiment is illustrated in fig. 7 including two antenna elements 12i and 12j. The first antenna element 12i is arranged as a substantially straight strip but the second antenna element 12j is provided with a curved section, bending over the first antenna element.

The antenna elements do not need to be small strips, but can be formed as wider strips with varying shape, as illustrated in figs. 8 and 9. The antenna element 12 according to fig 8 comprises a number of different connected triangular elements with different inclination and sizes for different frequency bands. The antenna element 12' according to fig. 9 has a larger upper section concentrating a larger metal to this section.

The antenna arrangement may also be connected to or cooperate with a whip antenna, e.g. arranged adjacent to or in a center section of the helix antenna. The antenna arrangement may also cooperate with a meander antenna.

Moreover, the conductive material, in its extension, may have different conductive characteristics.

The antenna device according to the invention is simple to manufacture. The process may comprise the following steps:

- cutting out pieces of substrate with suitable sizes with at least one defined edge, - applying a metal strip(s) using an appropriate metalization method with respect to a said defined edge as reference point,

- cleaning,

- And an additional step of arranging the antenna device comprising the substrate and antenna elements on or inside a carrier for producing a helix antenna, if such an antenna is needed.

The invention is not limited the shown embodiments but can be varied in a number of ways without departing from the scope of the appended claims and the arrangement and the method can be implemented in various ways depending on application, functional units, needs and requirements etc.

Claims

1. In a communications apparatus (8) a non-quadrifilar antenna arrangement (10) for single, dual and/or multi-band frequency including at least one antenna element (12a-12i, 12b-12j) arranged on at least one surface of a substantially flexible substrate (11) essentially entirely and continuously on said substrate (11) and shaped to a helix, characterised in, that said helix has a first and a second end, said first end being one end of said antenna element at one portion connected to one feeding line and said second end being free radiating.

2. An antenna arrangement according to claim 1, characterised in, that said antenna element (12a -12d) is arranged partly in a diagonal direction of said flexible substrate (11).

3. An antenna arrangement according to claim 1, characterised in, that said antenna element (12e, 12f) is arranged partly in a diagonal direction of said flexible substrate (11) having an originating point in a middle section of said substrate.

4. An antenna arrangement according to claim 1, characterised in, that said antenna element (12g) is arranged partly in a diagonal direction of said flexible substrate (11) having a branching constituting a second antenna element (12h).

5. An antenna arrangement according to claim 1, characterised in, that said antenna element (12, 12') comprises at least one geometrical shape with varying size.

6. An antenna arrangement according to claim 1, characterised in, that the antenna element (12j) is curved.

7. An antenna arrangement according to any of preceding claims, characterised in, that said antenna element has at least one signal feeding line (13, 13') on at least one comer section of said substantially flexible substrate (11).

8. An antenna arrangement according to any of preceding claims, characterised in, that said antenna element is arranged in said diagonal direction at least in one first angel (α, β) and one second angel (α', β') relative at least one edge of said substantially flexible substrate (11).

9. An antenna arrangement according to any of preceding claims, characterised in, that it comprises a first antenna element (12a-12i) having a first length and a second antenna element (12b-12j) having a second length.

10. An antenna arrangement according to claim 9, characterised in, that said antenna elements are arranged on opposites surfaces of said substrate.

11. An antenna arrangement according to claim 9, characterised in, that each antenna elements has one corresponding feeding point at opposite comers of said substrate.

12. An antenna arrangement according to any of the preceding claims, characterised in, that said substrate is deformed and arranged on, inside or embedded in a carrier (14).

13. An antenna arrangement according to claim 12, characterised in, that said carrier is a casing of the communication apparatus.

14. An antenna arrangement according to any of the preceding claims, characterised in, that said antenna arrangement cooperates with a whip antenna.

15. An antenna arrangement according to any of the preceding claims, characterised in, that said substrate is arranged with at least one recess.

16. A method for manufacturing a non-quadrifilar antenna arrangement (10) for single, dual and/or multi-band frequency including at least one antenna element (12a-12i, 12b-12j) essentially entirely and continuously arranged on at least one surface of a substantially flexible substrate (11), characterized in, that said method comprises the steps of:

- cutting out pieces of substrate in suitable sizes with at least one defined edge, - applying metal strip(s) using an appropriate metalization method with respect to said defined edge as reference point,