Abstract:
An electronics unit for wireless transfer of signals, includes an antenna part, an electronics part, and a transmission circuit part. The electronics part is placed on a laminate with at least one substrate layer of a dielectric material. The substrate layer is made of a flexible material and forms a continuous unit, including a first part which supports the electronics part, a second part which supports the antenna part, and a third part which supports the transmission circuit part. The second part of the substrate is formed to shape a convex surface, which supports groups of at least one antenna element. Since the surface is curved, the groups cover different directions.

Description:
TECHNICAL FIELD 
     The present invention relates to an electronics unit for wireless transfer of signals, which comprises an antenna part, transmission circuits and an electronics part. The unit is based on a laminate with a substrate layer of a dielectric material. 
     BACKGROUND OF THE INVENTION 
     When transferring signals by means of electromagnetic waves at high frequencies, to be more exact within the microwave area, microstrip technology is used both for the antenna part and the electronics part. Microstrip technology is a microwave technology which is based on laminates of two electrically conducting layers, and an intermediate dielectric layer. This dielectric layer is also called substrate, and serves not only as an isolating layer, but also as mechanical support for the electrically conducting layers. Previously known electronics units for the transfer of signals within a large angle divided into sectors consist of a separate electronics part and a separate antenna part, between which there are transmission circuits in the form of conventional cables. These are connected to each part by means of soldering or connectors. This previously known technology is expensive, and demands a great deal of space, and can cause interruptions in operation due to manufacturing errors, ageing, etc. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to obtain an electronics unit which is simple, cost efficient, saves space and provides good characteristics, since the invention solves the interface problems between the antenna part and the electronics part. 
     The said object is achieved by means of an electronics unit according to the present invention. This is characterized by a construction with substrate layers which are divided into three continuous sections, which are a first section which is part of the electronics part, a second section which forms the substrate in the antenna part, and a third section which supports the transmission circuits. The substrate extends continuously between the three sections, and is made of a flexible material, and is in the third section bent to a curved form. Its convex surface supports radiation elements, the beams of which, due to the bent surface, point in different directions. 
     Due to the construction according to the invention, an integrated unit is obtained with one and the same construction, and without intermediate organs such as solderings or connectors. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will in the following be described in closer detail using an example of an embodiment with reference to the appended drawings, in which: 
     FIGS. 1 and 2 show different perspective views of the electronics unit in one example of an embodiment, 
     FIG. 3 shows an opened view of the electronics unit, 
     FIG. 4 shows a side-view of the opened electronics unit, and 
     FIG. 5 shows a cross-section through the antenna part in the electronics unit, and 
     FIG. 6 schematically shows the construction of the antenna part. 
    
    
     DETAILED DESCRIPTION 
     As can best be seen in FIGS. 1 and 2, the antenna unit according to the invention consists of an electronics part  1 , an antenna part  2 , and a transmission circuit part  3  with transmission circuits  3  which form the interface between the electronics part and the antenna part. According to the invention, both the electronics part  1 , the antenna part  2 , and the transmission circuit part  3  are designed using the same construction, i.e. microstrip technology with a supporting structure, which according to the invention is a substrate which is common to both the electronics part  1 , the antenna part  2  and the transmission circuit part  3 . The antenna part  2  is of the conformal sector antenna kind, with a plurality of evenly spaced antenna elements  5 ,  6 ,  7 ,  8 ,  9 ,  10  around a cylinder  4 , see also FIG.  5 . The antenna is of the so-called multi-sector antenna kind, i.e. the antenna elements are so positioned that they together have a directivity in several (in the example shown, all) directions as seen in a plane which is perpendicular to the longitudinal axis  11  of the cylinder formed. 
     The electronics part  1  is in the example shown supported by a substrate  12 , which in connection to the electronics part preferably is plane, and also by a massive supporting structure  13  of metal which forms a base-part in the electronics unit. The electronics unit is advantageously shaped with an external contour, which in its entirety is cylindrically shaped, for which reason the base part is shaped with a side section  14 , with a cylindrical enveloping surface which becomes a cylindrical bottom plate  15 , on the bottom side of which connectors can be arranged for the connection of the electronics part to other units in, for example, a base station or a microwave link used for, for example telecommunications such as mobile telephony communication, data communication, video communication or other transfer of signals. The substrate in the electronics part  1  can form a supporting structure for analogue/digital electronics such as surface-mounted electronics, microstrip, transmission lines and the like. Said electronics can comprise further laminates. The example shown comprises an electronically controlled switch  18  for the connection of one or several of the antenna elements  5 - 10  according to certain chosen criteria for transmission and reception in chosen antenna sectors via each transmission circuit  3  in a manner which as such is known. The electrically controlled switch  18  is controlled via a (not shown) control connection. 
     With reference to FIGS. 4,  5  and  6 , the construction according to the invention will in the following be described in more detail. As mentioned above, the electronics part  1 , the antenna part  2  and the transmission circuit part  3  with the connecting transmission circuits  3 ′, are supported on a continuous common flexible substrate  12 , which is manufactured from, for example, a polymer, for example tetrafluorethylene. The laminate also comprises a ground plane  21  across the entire surface of the substrate on one of its sides, and the transmission circuits  3 ′ in the form of microstrip conductors on its other side. In the antenna part, there are arranged sections  24  of a second substrate, to be more exact one section for each antenna element  5 . These substrate sections  24  are spaced apart from each other, and on their outside support antenna elements  5 - 10 , for example so-called patches in the form of copper layers which can exhibit a suitable form, for example a rectangular or circular form. The antenna elements can be arranged in groups comprising one or several antenna elements. Due to the curved surface, the groups point in different directions. 
     As can be seen in FIG. 3, the basic part of the common substrate for the electronics part  1 , the antenna part  2  and the transmission circuit part  3  is a plane substrate piece, which in the example shown essentially is T-shaped, where a part of the “leg” forms a first part  22  of the substrate which serves as a support for the electronics part, and the cross-bar forms a second part  23  of the substrate, which serves as support for the antenna part  2 , and an interface between the first and the second part forms a third part  20  of the substrate, which forms a support for the transmission circuit part  3 . The final shape of the antenna part  2  is obtained by bending the cross-bar  23 , i.e. the second part with its ground plane and any other layers. In the example shown the cross-bar is bent to a shape which essentially is cylindrically formed. By means of a certain reduced elasticity in the sections  24  of the second substrate, in practice a certain stiffening is obtained of these parts in relation to the intervals  25  which are formed between the sections. Although FIG. 5, for reasons of simplicity, shows only arc-shaped lines, the shape can in practice become polygonal, thus causing essentially plane antenna elements  5 - 10 . The cross-bar  23  of the substrate piece is dimensioned so that the two outer edges  26 ,  27  will essentially meet, to form a closed convex enveloping surface with a chosen diameter. The ground plane  21  is bent together with the substrate  12 , so that it, similarly to the substrate, is given a bent shape. For reasons of simplicity, the ground plane in FIG. 5 is shown as a thick circumferential arc line. 
     One and the same substrate layer  12  thus forms a continuous supporting structure both for the electronics part  1 , the antenna part, and the transmission circuits  3 ′ of the transmission circuit part  3  which extend between them. The ground plane  21  can, similarly to the substrate  20 , be considered to consist of three continuous sections in the form of an electrically conducting layer which extends across both the electronics part  1 , the antenna part  2  and the transmission circuit part  3 . This forms the above-mentioned interface, by means of which the transmission circuits extend from the electronics part  1  and into the antenna part  2 , to be more exact one conductor all the way up to a chosen point, at least up to the area of each aperture  35 . 
     As can be seen in FIG. 5, the antenna part  2  exhibits a body  28  of metal which, in the example shown, has six radially extending walls  29 ,  30  which extend from a center which coincides with the axis of symmetry  11 . The body  28 , due to its design, delimits a chamber  31  behind each antenna element  5 - 10 . These chambers  31  suppress radiation in the backwards and side directions, both from the antenna elements and from the transmission circuits  3 , which reduces the problem of interference between the radiating components. The chambers also form cavities which affect the impedance adjustment of the antenna element. The body  28  has radially outwards facing end surfaces  32 , against which the substrate  20  obtains support with its inside. The bent substrate layer can be attached to the end surfaces, for example by means of screws through holes  17 , see FIG.  3 . 
     Radially outside of the antenna element  5 - 10  there is arranged a cover  33 , which is tube-shaped and preferably cylindrical, and which is designed in a known manner in a material with low attenuation of electromagnetic waves. The cover  33  forms a radome, and also an outer mechanical support and protection for the substrate part  23  of the antenna part which is bent to a convex shape, and which, if it has elastic properties, thus is contained to the predetermined form due to interaction with the body  28  from the inside. The radome  33  extends in the direction of the longitudinal axis  11 , at least enough to cover the height of the substrate part  23 . The radome can advantageously exhibit a closed end wall above the antenna part  2 , and can also surround the electronics part  1  and the transmission circuit part  3 , which however is not shown. 
     FIG. 6 shows the above-mentioned substrate construction with the first substrate  12 , from which it can be seen that the ground plane  21  exhibits oblique slit-shaped openings  35 , so-called apertures which, as such, are previously known, and which form radiation elements in order to transfer the microwave energy from the transmission circuits  3  to the antenna element  5 , which in turn during transmission radiate in an outwards direction in a chosen sector. During reception, the microwave radiation goes in the opposite direction. 
     The invention is not limited to the examples of embodiments described above and shown in the figures, but can be varied within the scope of the appended claims. For example, the antenna elements  5 - 10  can have another shape, or their amount can be larger or smaller. Furthermore, each antenna element can be extended to a group of radiation elements in the same direction, for example to alter the beam-shape in a plane parallel to the cylinder axis  11 . Furthermore, the patches, and thus the second substrate  24  are not a necessary condition in order to carry out the invention. In principle, both the body  28  and the radome  33  can be left out.