AU668748B2

AU668748B2 - Mobile radiotelephone having asymmetric radiation pattern

Info

Publication number: AU668748B2
Application number: AU46075/93A
Authority: AU
Inventors: Claudio Maggio; Luigi Panico
Original assignee: Alcatel NV
Current assignee: Alcatel Lucent NV
Priority date: 1992-09-18
Filing date: 1993-09-03
Publication date: 1996-05-16
Anticipated expiration: 2013-09-03
Also published as: EP0588271B1; AU4607593A; EP0588271A1; ITMI922146A1; NZ248624A; DE69318361T2; IT1255602B; ES2116378T3; ATE165942T1; ITMI922146A0; DK0588271T3; DE69318361D1

Abstract

The present invention relates to a portable transceiver apparatus, in particular a radiomobile telephone set, with low irradiation of the user, comprising a handset and an antenna, having an asymmetric radiation pattern, applied to said handset. Since such apparatuses, when in use, are placed alongside the user's head, a great amount of electromagnetic waves pass through it, in particular with the continuous increase in the transmission frequency and the consequent decrease in the dimension of the antenna the irradiation of the user's head is and will become a serious problem. The aim of the invention is to provide a portable transceiver apparatus so as to minimize the irradiation of its user. By using an antenna having an asymmetric irradiation pattern such as to be extremely limited in the directions of the user's head, a greatly reduced irradiation can be obtained. <IMAGE>

Description

8 j748 P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "MOBILE RADIOTELEPHONE HAVING ASYMMETRIC RADIATION

PATTERN"

The following statement is a full description of this invention, including the best method of performing it known to us:-

MEMO--

x~ IYPII~----^DI1^ 2 This invention relates to mobile radio telephone sets having a handset and an antenna attached to said handset, and in particular to a mobile radio telephone with low irradiation of the user by energy radiated from the antenna.

In Figs. 1 and 2 of the accompanying drawings, there are illustrated schematically in a side view two known mobile radio apparatuses; Fig. 1 shows the Motorola 8800X model and Fig. 2 shows the 9800X model. The schematic side view of Fig. 1 is typical of all the protable transceiver apparatuses. Such apparatuses basically comprise a handset AC and an antenna AA attached to the handset.

Located inside said handset generally are a loudspeaker AL, a microphone AM, a control panel AK and the circuitry for operating the apparatus.

The antenna AA of a mobile radio telephone set is placed in the upper portion of the handset AC; several models, all of the retractile and fixed whip type are available.

Since such apparatuses, when in use, are placed alongside the user's head, a S 15 substantial amount of electromagnetic waves pass through the head. With the 4 [o continuous increase in the frequency used for transmission, at present a 900 MHz frequency is used but the trend is to achieve 60 GHz in the future, the dimensions of S4the antenna decrease and therefore the distance between the antenna and the user's head will become practically nil. Irradiation of the user's head is and will 20 become a serious problem, particularly if the increase in transmission frequency is taken into account.

SIt is an object of tne present invention to provide a portable transceiver apparatus arranged to minimize the irradiation of the head of a user.

According to the invention there is provided a portable transceiver apparatus, including a handset and an antenna attached to said handset, wherein said antenna is of the type which produces a substantially unidirectional radiation pattern, and wherein said antenna is arranged such that the said radiation pattern's major lobe is in a direction that extends away from the head of a user when said apparatus is in a position proximate the head for normal use.

By using an antenna having a suitable asymmetric radiation pattern, such as to be extremely limited in the direction of the user's head, a considerable reduction Sin the irradiation can be obtained.

In order that the invention may be readily carried into effect, an embodiment thereof will now be described in relation to the accompanying drawings, in which: Figs. 1 and 2 represent schematic side views of two prior art appasratuses, and Fig. 3 is a possible radiation pattern of the handset-antenna assembly in accordance with the present invention, represented in overlap to an apparatus and to the user's head.

From Figs. 1 and 2 two schematic side views of two prior art portable transceiver apparatuses can be seen; for the purpose of describing the present invention it will suffice to say that such apparatuses comprise a handset AC and an antenna AA applied to the handset AC.

As already said, the solution, in accordance with the present invention, for limited the irradiation of the user's head caused by a portable transceiver apparatus consists in using an antenna AA having a suitable asymmetric radiation pattern, such as to be extremely limited in the direction of the user;s head.

Naturally the radiation pattern of antenna AA is modified by the handset AC and its content and therefore, for precision's sake, it would be necessary to consider the overall radiation pattern; very often, the contribution from handset AC can be, at least in a first approximation, neglected or made negligible by screening the handset AC itself.

In Fig. 3, there is shown one of may possible radiation patterns RD of the assembly formed by handset AC and antenna AA in accordance with the present invention, represented in overlap to an apparatus and to the head U of its user.

Such radiation patterns having special shape can be obtained through suitable choice of the type and shape of antenna AA.

A first possibility consists in using a screened whip antenna. Another possibility is to use high frequency antenna arrays.

An exhaustive treatment of this topic can be obtained from H. Jasik, Antenna Engineering Handbook, McGraw-Hill, in particular chap. 21 (High-Frequency Arrays) and from section 30.6 (Strip Transmission Lines).

Such arrays basically comprise at least one horizontal-dipole radiator located at a suitable distance from a horizontal conducting plane.

Several dipoles may be placed in parallel to form bays and several bays can 4 be associated to form curtains. Depending on the number and position, the radiation pattern assumes special shapes respectively increasing the vertical and horizontal directivity.

In addition to the radiators(s) at least one reflector can be placed in the back zone to limit the radiation pattern in suitable directions; such reflectors can be constituted by tuned dipoles operating in a passive manner, or by a vertical relecting screen, composed of densely-spaced horizontal turns.

Other types of antennas usable individually or in array fashion are, e.g., horizontal rhombic antennas, long singlewire antennas, horizontal V antennas both resonant and terminated.

It is clear that in order to implement advantageously such types of antennae S1 for use on portable transceiver apparatuses one must be able to reduce at the maximum extent their overall dimensions. Variously-shaped microstrip structures and, in addition, metal conducting planes are then used, if required; all being 15 arranged ona substrate.

o An exhaustive treatment on microstrip antennae can be found both in the 4 4above-mentioned antenna engineering hand boom and in Collin, Robert "Antennas and Radiowave Propagation" McGraw-Hill, in particular at section 4.14 (Microstrip i Antennas).

If the antenna is mounted on a board, when the apparatus is not in use, the antenna can be located inside it and, when the apparatus is to be used, it can be drawn out by sliding or by turning over; this in order to reduce the overall dimensions and the handiness of the apparatus when not in use of course.

i The possible conformations of the microstrip structures which form the antenna are very many and those skilled in the art will be able to find the one which 1 is best suitable for his needs in terms of operating frequency band, of directivity and of gain.

i r

Claims

1. A portable transceiver apparatus, including a handset and an antenna attached to said handset, wherein said antenna is of the type which produces a substantially unidirectional radiation pattern, and wherein said antenna is arranged such that the said radiation pattern's m-jor lobe is in a direction that extends away from the head of a user when said apparatus is in a position proximate the head for normal use.

3. An apparatus as claimed in claim 1, wherein said antenna comprises at least one horizontal dipole radiator disposed at a suitable distance from a horizontal conducting plane.

4. An apparatus as claimed in claim 3, wherein said antenna further comprises at least one reflector placed behind said radiator. An apparatus as claimed in claim 1,wherein said antenna is a rhombic antenna.

6. An apparatus as calimed in claim 1, wherein said antenna is a long single- wire antenna.

7. An apparatus as claimed in claim 1, wherein said antenna is a resonant or terminated V antenna.

8. An apparatus as claimed in claim 1, wherein said antenna comprises variously conformed microstrip structures.

9. An apparatus as claimed in claim 8, wherein said antenna further comprises metallic conducting planes. An apparatus as claimed in claim 8, wherein said antenna is housed on a board that is located inside the apparatus when the latter is not used and can be 25 drawn out by sliding or by turning over when the apparatus is to be used.

11. An apparatus substantially as herein described with reference to Figure 3 of the accompanying drawings. DATED THIS THIRTEENTH DAY OF MARCH 1996 ALCATEL N.V. ABSTRACT A portable transceiver apparatus, in particular a mobile radio telephone set, with low irradiation of the user, comprising a handset (ACI and an antenna (AA), having an asymmetric radiation pattern applied to said handset. Since such apparatuses, when in use, are placed alongside the user's head a substantial amount of electromagnetic waves pass through the user's head. With the continuous increase in the transmission frequency and the consequent decrease in the dimension of the antenna the irradiation of the user's head is and will become a serious problem. The invention provides a portable transceiver apparatus arrangement which min imises the irradiation of its user. By using an antenna having an asymmetric irradiation pattern (RD) such as to be extremely limited in the directions of the user's head, a greatly reduced irradiation can be obtained. i;