HAND-HELD TRANSMITTING AND/OR RECEIVING APPARATUS

Abstract: Hand-held transmitting and/or receiving apparatus, comprising a housing made from non-conducting material, an electric circuit inside the housing, an electrical ground plane inside the housing, an antenna resonator element arranged approximately parallel to the ground plane and having a first free end and a second end which is electrically connected by a ground connector to the ground plane and means for connecting the ground plane and the resonator element to the electric circuit. The resonator element, the ground plane and the ground connector are fixed on a separate dielectric body positioned inside the housing. This antenna is simple to manufacture and the dependence of the electrical parameters of the antenna from mechanical tolerances and from mechanical and thermal influences is reduced.

Description: Hand-held transmitting and/or receiving apparatus The invention relates to a hand-held transmitting and/or receiving apparatus comprising a housing made from non-conducting material, an electric circuit inside the hou¬ sing, an electrical ground plane inside the housing made from non-conducting material, an antenna resonator element arranged approximately parallel to the ground plane and hav¬ ing a first free end and a second end which is electrically connected by a ground connector to the ground plane and means for connecting the ground plane and the resonator element to the electric circuit. An apparatus of this kind is disclosed in EP 0 484 454 Bl where the antenna resonator element has the form of an angled metal sheet of metal foil applied on the outside of the plastic housing. The electrical ground plane has the form of a shielding housing inside the plastic housing which shielding housing contains the electric circuit. Between the shielding housing and the plastic housing in the area of the antenna resonator element an air gap is located. An earthing lead through extends through a slit in the plastic housing and connects the angled leg of the L-shaped antenna resona¬ tor element to the shielding housing. This known apparatus has the disadvantage that it is difficult to form the slit in the plastic housing for the lead through. Either the slit must be formed when forming the housing or the slit has to be cut after that. Further¬ more it is difficult to provide the ground connector leading through the slit and to connect it to the antenna resonator at the one hand and to the shielding housing inside the pla¬ stic housing on the other hand. An important electrical disadvantage of this known apparatus results from the air gap between the shielding housing and the plastic housing on which an antenna resona- tor element is fixed. The electrical parameters of the res¬ onator element are dependent from this air gap. Since toler¬ ances of the dimensions of this air gap and changes in dependence from mechanical and thermical influences are una¬ voidable it is not possible to assure and keep constant the electrical parameters of the antenna. The result are mismat¬ ching, standing waves on the feed line to the antenna and changes of the radiation pattern. The object of the invention is to overcome the disad¬ vantages of this state of the art namely to simplify the manufacture and to reduce the dependence of the electrical parameters of the antenna from mechanical tolerances and from mechanical and thermal influences. The basic idea of the invention is to fix all parts of the antenna namely the resonator elements, the ground plane and the ground connector on a separate dielectric body. The result is that there is no air gap between the conductive elements of the antenna and the dielectric body. So the electric parameters of the antenna are only dependent from the thickness of the dielectric body and the dielectric values of the material of this body. It is easy to assure low tolerances of the thickness of the body during manufac¬ turing. Also variations by time are low. According to one embodiment of the invention the reson¬ ant element, the ground plane and the ground connector are in the form of an electrically conducting layer or coating on the dielectric body. This antenna unit is simply to manu¬ facture and it can be tuned before assembling and bringing the antenna into the housing. The dielectric body with the ground plane may extend over approximately the whole internal width of the housing while the ground plane is connected to ground of the elec¬ tric circuit and covers at least a part of the electric cir¬ cuit. Thus the ground plane serves as a shield for the elec- trie circuit. The resonator element may have approximately the same width as the ground plane giving a good broad band charac¬ teristic of the antenna. The same advantage results from a further improvement according to which a ground connector extends over the whole width of *the resonator element. According to a further improvement an elongated feeder element is provided positioned at one side of the resonator element for coupling the feeder element to the resonator element, one end of the feeder element representing a feed- ing end coupled to the means for connecting the resonator element to the electric circuit. This improvement avoids a galvanic contact between the electric circuit and the res¬ onator element. Preferably the feeder element extends over approximately the whole length of the resonator element. By this an electromagnetic coupling is achieved. Additionally the feeding end of the feeder element can be positioned at the free end of the resonant element. According to one improvement of the invention where the conductive elements of the antenna unit are in the form of an electrically conducting layer or coating on the dielec¬ tric body a projection is provided at the edge of the free end of the resonator element. The projection has a smaller width than the resonator element. By adjusting the length of the projection the resonant frequency of the resonator element can be tuned. Preferably the width of the projection is ten times or more less than the width of the resonator element. By this dimensioning of the projection a fine tun¬ ing of the resonator element is possible. According to one improvement of the invention the ground plane and/or the resonator element and/or the feeding element are connected to the electric circuit by elastic and electrically conducting material positioned under pressure between opposite contact points or contact lines. This has the advantage that the connections between the antenna unit and the electric circuit are made automatically during assembling when the antenna unit is inserted into the hous¬ ing. According to one improvement of the invention the dielectric body has a recess the surface of which is covered with the conducting layer of the ground plane. Said recess is surrounded by protrusions or ribs covered with the con¬ ducting layer of the ground plane for connecting the ground plane to ground of the electric circuit. By this a screened cavity for elements of the electric circuit is provided. Instead of one single antenna resonator element at least two resonator elements may be located over the ground plane. In the following the invention will be described in more details by way of examples shown in the drawings in which Fig. 1 is a sectional diagrammatic view of one example of the invention where the electric circuit is omitted, Fig. 2 is a sectional magnified view showing in more detail the upper part of Fig. 1 and Fig. 3 is a perspective view of the antenna unit in Fig. 2. Fig. 1 is a diagrammatic sectional view of a hand-held transceiver comprising a housing 1 made from non-conducting material, an earphone 2, a microphone 3 and an antenna unit 4 consisting of an resonator element 5, a ground plane 6 and a ground connector 7 connecting one end of the resonator element 5 to the ground plane 6. An electrical circuit is positioned inside the housing 1 but not shown. The antenna element 5, the ground plane 6 and the ground connector 7 are conducting layers on a separate dielectric body 8 altogether forming the independent antenna unit 4 which is fixed to the inner wall of the housing 1. The antenna unit 4 may be clamped beween the housing 1 and the electric circuit for mechanical holding and/or electri¬ cal connecting purposes. Since all electric elements of the antenna are inside the housing 1 it in any case is easier to connect the electric elements of the antenna to the electric circuit inside the housing 1. Fig. 2 shows in more detail a sectional view through the upper part of another example of a hand-held apparatus with an antenna arrangement similar to that of Fig. 1. Inside a wall 9 of a housing 10 most of which is broken away an antenna unit 11 is positioned consisting of a dielectric body 12 on which in form of electric layers an antenna res¬ onator element 13, a ground connector 14 and a ground plane 15 are fixed. The ground plane 15 has protrusions 16 and 17 contacting a conducting elastic layer 18 on a circuit board 19 carrying the electrical leads and elements not shown in known manner. The dielectric body 12 has a recess 20 so providing a cavity 21 into which circuit elements on the circuit board 19 may extend which are so well-screened by the electric layer of the ground plane 15. Fig. 3 shows the antenna unit 11 comprising the dielec¬ tric body 12, the resonant element 13, the ground connector 14 and the ground plane 15 in perspective view. It can be seen that from an edge 22 of the free end of the resonant element 13 a projection 23 extends the width of which is much smaller than the width of the resonant element 13. The projection 23 can be shortened for tuning purposes. In Fig. 3 furthermore can be seen that at one side of the resonant element 13 a feeder element 24 is fixed on the surface of the dielectric body 12, said feeder element 24 extending approximately over the whole length of the resona- tor element 13. The free end of the feeder element 24 is near the ground connector 14 while another end 25 of the feeder element 24 extends to that side of the dielectric body 12 where the ground plane 15 is located. Therefore the feeder element 24 can be connected to the electric leads of the circuit board 19 by a small -conducting and elastic layer just in the same manner as the ground plane 15 is connected to the circuit board 19 by the layer 17.

Claims: C l a i m s 1. Hand-held transmitting and/or receiving apparatus, com¬ prising a housing made from non-conducting material an electric circuit inside the housing an electrical ground plane inside the housing - an antenna resonator element arranged approximate¬ ly parallel to the ground plane and having a first free end and a second end which is electrically connected by a ground connector to the ground plane and means for connecting the ground plane and the res¬ onator element to the electric circuit, characterized in that the resonator element (5, 13), the ground plane (6, 15) and the ground connector (7, 14) are fixed on a separate dielectric body (8, 12) positioned inside the housing (1). 2. Apparatus according to claim 1, characterized in that the resonator element (13), the ground plane (15) and the ground connector (14) are in the form of an electrically conducting layer or coating on the dielectric body (12). 3. Apparatus according to claim 2, characterized in that the dielectric body (12) with the ground plane (15) extend over approximately the whole internal width of the housing (10) and that the ground plane (15) is connected to ground of the electric circuit on an electric circuit board (19) and covers at least a part of the electric circuit. 4. Apparatus according- to claim 2, characterized in that the resonator element (13) has approximately the same width as the ground plane (15). 5. Apparatus according to claim 2, characterized in that the ground connector (14) extends over the whole width of the resonator element ( 13 ) . 6. Apparatus according to claim 2, characterized in that an elongated feeder element (24) is positioned at one side of the resonator element (13) for coupling the feeder element (24) to the resonator element (13), one end (25) of the feeder element (24) representing a feeding end and being coupled to the means for connecting the resonator element (13) to the electric circuit. 7. Apparatus according to claim 6, characterized in that the feeder element (24) extends over approximately the whole length of the resonator element (13). 8. Apparatus according to claim 6, characterized in that the feeding end of the feeder element (24) is positioned at the free end of the resonant element (13). 9. Apparatus according to claim 2, characterized in that a projection (23) is provided at the edge (22) of the free end of the resonator element (13) the projection (23) having a smaller width than the resonator element (13). 10. Apparatus according to claim 9, characterized in that the width of the projection (23) is ten times or more less than the width of the resonator element (13). 11. Apparatus according to claim 1 or 6, characterized in that the ground plane (15) and/or the resonator element (13) and/or the feeder element (24) are connected to the electric circuit by elastic and electrically conducting material positioned under pressure between opposite contact points or contact lines. 12. Apparatus according to claim 2, characterized in that the dielectric body (12) has a recess (20) the surface of which is covered with the conducting layer of the ground plane (15) and that said recess (20) is surrounded by pro¬ trusions (16, 17) covered with the conducting layer of the ground plane (15) for connecting the ground plane (15) to ground of the electric circuit and so providing a screened cavity (21) for elements of the electric circuit. 13. Apparatus according to claim 1, characterized in that at least two separate resonator elements are located over the ground plane.

Inventors: PEDERSEN GERT FROELUND, THOMSEN JAN GERT, PEDERSEN, GERT, FROELUND, THOMSEN, JAN, GERT
Applicants: CETELCO AS, PEDERSEN GERT FROELUND, THOMSEN JAN GERT, CETELCO CELLULAR TELEPHONE COMPANY A/S, PEDERSEN, GERT, FROELUND, THOMSEN, JAN, GERT
Application year: 1995
Main classification: H01Q1
IPC codes: H01Q1, H01Q9