MXPA98005500A - An assembly of ant - Google Patents

Abstract

The present invention relates to the integral antenna assemblies and in particular relates to an integral antenna assembly for the microcellular base stations and the wireless fixed access base stations; power mechanism for the same. According to one aspect of the invention, there is provided an integral antenna comprising a dome, a layered antenna and a support plane of the reflector, wherein the layers have an outer surface and a rear surface, wherein the dome is attached directly to an outer surface of the antenna, and wherein the support plane provides a reflection cavity and encloses the supply network for the antenna and joins the back surface of the antenna. According to another aspect of the invention, the method of operation of an integral antenna comprises a dome, a dielectric substrate having a patch antenna element on a surface thereof and a support plane of the reflector providing a reflection cavity. behind the radiation element, where the dome is attached directly to an outer surface of the dielectric and the support plane of the reflector is attached to the back surface of the dielectric, the patch is connected through the substrate to a power supply line. the microstrip, with which the feeding line of the microstrip falls parallel to the patch, with the patch acting as a floor with respect to the line of the microstrip, where the antenna transmits and receives signals via the power network.

Description

AN ANTENNA ASSEMBLY Field of the Invention The present invention relates to antennas and in particular relates to an integral antenna assembly antenna as used for example in microcellular communication systems and wireless fixed access systems.

Background of the Invention For modern telecommunications applications, apart from the electrical operation of the antenna, other factors such as the size, weight, cost and ease of construction of the antenna need to be taken into account. Depending on the requirements, an antenna can be either a simple element of radiation or a set of similar radiation elements. With the increased deployment of cellular radio, an increased number of base stations communicating with mobile handhelds is required.

Similarly, an increased number of antennas are required for the deployment of fixed wireless access systems, both on the premises of subscribers and base stations. These antennas are required both cheap and easy to produce. An additional requirement is that the structures of the antennas are of light weight but nevertheless have sufficient strength to be placed on the top of the support poles, roofs and similar places, and maintain long-term operation during the extremes enviroment.

Antennas for cellular radio systems need to use low cost manufacturing methods. This is particularly important for microcellular and fixed wireless systems where the costs of the antenna can be a significant part of the costs of the system under the requirements for a high deployment of the base stations.

An antenna that is built in the shelter of the base station is a type of antenna that reduces the environmental impact the base station will use. This type of antenna is known as an internal antenna and can potentially reduce the costs of both the antenna and its installation. In addition, being built in the base station the environmental impact of the system is reduced by minimizing the amount and size of the separate trajectories. It is also required that the antenna be lightweight.

The patch antennas comprise one or more rectilinear conductive or ellipsoidal patches supported in relation to a floor plane and radiate in a direction substantially perpendicular to the floor plane. Conveniently, antennas per patch are formed using icrocyte techniques; A dielectric can have a patch printed on it in a manner similar to the printing of the feeding probes employed in the layered antennas.

An antenna for fixed wireless access facilities employing patch antenna distribution is described in British Patent Application GB 9425751.6. The antenna comprises twelve patch elements distributed within a generally octagonal environment; the elements are printed on the dielectric sheet suspended between the plane of the reflector floor and the dome by dielectric dividers. The plane of the reflector floor has depressions that correspond in position with that of the printed radiation elements, with which, inter alia, the supply lines of microscissors are sufficiently close to the plane of the floor to control the radiation of the power line, while the space behind the radiation elements is sufficient to increase the width of the antenna band. The exterior dielectric is made of expanded polystyrene and, as such, this divider will retain moisture that can reduce operation operation. The antenna has relatively large z-axis dimensions (ie, dimensions in the direction of propagation).

An additional type of antenna is known from the United States patent with US-A-5499033 (Northern Telecom) that provides a linear distribution of radiation elements, using an essentially tri-plate / layered antenna. These antennas are typically used in groups with a random distribution to cover and protect the radiation elements, simply or otherwise. As for the antenna described above, the dielectric divider (foam in this case) used to place the radiation elements in relation to the open floor plans, can retain moisture which in turn can affect the operation of the antenna.

Objective of the Invention The present invention seeks to provide an integral antenna assembly for integration with an icrocellular base receiving transmitter station or a wireless fixed access base station.

Situation of the Invention According to a first aspect of the invention, there is provided an integral antenna comprising a dome, a layered antenna and a reflector rear plane wherein the layers have an outer surface and a rear surface; wherein the dome is attached directly to an outer surface of the antenna; and wherein the rear plane provides a reflection cavity and encloses the supply network for the antenna and is attached to the rear surface of the antenna. By attaching the dome directly to the antenna, the structure of the antenna increases its strength and there is no cavity between the antenna and the dome in which moisture could accumulate. This humidity would affect the performance of the antenna, both in electrical terms and also in terms of resistance to corrosion - it has been found that by placing the dome adjacent to the structure of the antenna, the pattern of the radiation is not compromised. In addition, the construction also provides an environmental seal for the antenna to prevent degradation of antenna performance during its lifetime due to moisture-induced corrosion, etc.

Moreover, the present invention can provide a protective cover that is aesthetically pleasing and mechanically strong, for the electronics of the base station. By having the dome attached to the structure of the antenna, the overall size of the antenna structure is reduced, with the result that the planning permission required for the installation of these structures is less likely to be refused. The present invention provides a means to increase the construction opportunities of an antenna that when installed is more likely to mix with the existing architecture. The invention also provides a construction that allows the individual parts of the antenna to serve multiple purposes and therefore meet the requirements of low cost, light weight and efficient RF operation.

The antenna can be of a triple plate structure, comprising two floor planes of which at least one is open and a dielectric element supporting a power network and the radiation elements; the dielectric substrate is supported between the two floor planes. The invention can be applied to a wide range of "flat" antenna element types such as spirals supported by cavities or slots.

In accordance with another aspect of the invention, a patch antenna is provided which includes a dome, a dielectric substrate having an antenna element oriented on the surface thereof and a back plane of the reflector which provides a reflection cavity behind the reflector. the elements of radiation; where the dome is directly connected to an outer surface of the dielectric plane and the rear reflector plane is joined to a back surface of the dielectric substrate. The patch radiation element can be printed on a first side of a dielectric substrate, the patch element is in connection with a microstrip feed thereof on a second side of the substrate and a plane of the reflector floor; wherein the dome is attached directly to the surface of the dielectric that supports the printed elements of the antenna; the microstrip feeding line is connected through the substrate of the patch, with which the feeding line of the microstrip falls parallel to the patch with the patch acting as a floor with respect to the microstrip line. The back plane of the reflector can be attached directly to the dielectric substrate.

The patches can be rectilinear or ellipsoidal, and can have one or more feeds. Preferably the protective floor is placed on the surface of the dial that supports the patch element. The patch and the floor plan with this cover the fine micro-tape feed and the distribution network of any polarization. This type of power distribution can provide an optimal feeding point location for any polarization. In a polarized dual mode, there is no compromise in cross polar operation or impedance matching.

An adaptation network can be placed on the dielectric of the antenna. Preferably this network is placed on the opposite side of the dielectric and covered by the floor plane. Through the use of microstrip printing techniques, a patch antenna can simply be manufactured effectively and cost effectively; Very few steps of the process that are involved in the production and microstrip techniques are well developed. The adaptation network can be formed with discrete components.

According to a further aspect of the invention, there is provided an integral antenna comprising a dome, a dielectric substrate having a patch antenna element on a surface thereof and a back plane of the reflector providing a reflection cavity behind the radiation element; wherein the dome is attached directly to an outer surface of the dielectric and the back plane of the reflector is attached to a back surface of the dielectric substrate. The patch radiation element may be printed on a first side of the dielectric substrate; wherein the dome is attached directly to the surface of the dielectric that supports the elements of the printed antenna; the patch is connected through the substrate to a feeding line of the microstrip with which the feeding line of the microstrip falls parallel to the patch, with the patch acting as a floor in relation to the line of the microstrip.

A method for operating an integral antenna comprising a dome, a dielectric substrate having an antenna element on the surface thereof and a rear plane of the reflector providing a cavity behind the radiation element is provided; wherein the dome is attached directly to a back surface of the dielectric; the antenna is connected through the substrate to a radio frequency feed line, where the antenna transmits and receives signals via the power network.

In accordance with another aspect of the invention, there is provided a method for operating an integral antenna comprising a dome, a dielectric substrate having a patch antenna element on a surface thereof and a back plane of the reflector providing a cavity of reflection behind the radiation element; wherein the dome is attached directly to an outer surface of the dielectric and the back plane of the reflector is attached to a back surface of the dielectric; the patch is connected through the substrate to a microstrip feeding line, whereby the microstrip feeding line falls parallel to the patch, with the patch acting as a floor with respect to the microstrip line, where the antenna transmits and receives signals via the power network.

Description of the Drawings In order that the present invention can be fully understood and to show how it can be carried out in effect, the references will now be made by way of example only with the Figures that are shown in the accompanying sheets of drawings, where : Figures 1 and 2 show the basic construction of an antenna assembly made in accordance with the invention: Figure 3 shows the arrangement of a first antenna; Figure 4 shows a perspective view, a plane of the molded floor, operable in the manner shown in Figure 3; Figure 5 is a view of the plane of the antenna shown in Figure 4; Figures ßa, ßb and ßc are cross sections through Figure 5 along the lines C-C 1, B-B1 and E-E respectively; Figures 7 and 8 show the detailed plan and sectional cross-sectional views of a first patch configuration.

Figures 9 and 10 show the detailed plan and sectional cross-sectional views of a second patch configuration.

Figures 11 and 12 show the detailed plan and sectional cross-sectional views of a third patch configuration.

Detailed Description of the Preferred Modalities The best embodiment contemplated by the inventors for carrying out the invention will now be described by way of example. In the following description, amount of specific details are set forth in order to provide a complete understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be practiced with specific variations.

Figures 1 and 2 show two distributions for an integral antenna according to the invention. The cover can be either flat or curved. A curved surface is often used to provide greater structural strength and for many it is seen in a more pleasurable way. The antenna comprises a dome 114, a dielectric board 116 with a patch antenna 118 defined therein and a floor plan of the molded reflector 120. The dome is made using a suitable dielectric material such as fiberglass, reinforced plastics or ABS plastics and is molded to conform to the radiation elements and can be painted to provide a cover that is aesthetically pleasing. This cover can also act as a sun protection to reduce the effects of solar radiation heating and impact protection to avoid mechanical damage to the electronics of the base station. There is a wide choice of available materials known to those skilled in the art. The floor plan is conveniently formed from aluminum to provide a lightweight structure, although materials such as zinc-plated steel can also be employed. The fins of the optional heat sink 122 are shown and are in intimate contact with the floor plane, although this is not clear in the Figures. The support plate provides the reflective floor plane for the cavities below the patch antennas, although in these Figures the cavity depth is larger than would normally be the case for the 2 GHz sub-signals. Support can be glued to the printed circuit board using an adhesive such as a THESA adhesive system (such as types 4965 or 4970). The contact with the floor must be maintained. Similarly, the dome can be glued to the radiation side of the printed circuit board. The formed support offers environmental protection and can provide a seal against the entry of moisture at the edges.

Microstrip losses and board control (E, and tan) are tolerable with the use of Getek (TM) in both 900 and 1800 MHz. The Getek board is an alternative to the FR-4 board and provides a board with a reasonable degree of control over dielectric constant propagation. No foam is used that can retain water; the dome is strengthened by means of the dielectric and the back plane. A variety of feeding methods can be employed for the antenna elements to achieve both adaptation and dual polarization. The absence of the foam dividers helps to increase the mechanical strength together with the molded support plate.

In addition, to provide environmental protection against moisture, etc., the molded support plate provides an integrated cable path and a strain relief, which is dispensed with the need for cable connectors and locks.

Referring now to a particular configuration of the antenna, Figure 3 shows a first antenna. Two circular patches were chosen to reserve space for a distribution network, especially because square patches at ± 450 would increase the width and length of an integral antenna. The antennas are operable in both transmission and reception in the two orthogonal polarizations and exhibit an appropriate antenna pattern. Figure 3 shows the patches 78, 80 and the plane of the floor 82 on a first side of a delectric substrate 84 and a network of line / feed microscissors 86 on a second side of the dielectric. For reasons of convenience, Figure 3 shows two types of microstrip feed lines for the patches. A first type of feed Fl provides the connection of the first polarization patches and two separate foods F2 can be fed independently, which is not the case for foods Fl. The soldered pads 88, 90, 92, provide the points of contact to receive the input signals from, for example, a coaxial cable. The arms of the microstrip 94 have a first width, a second width 96 for adaptation purposes and a third width 100 as it passes under the patches 78, 80. In the figure, the periphery of the patches has an annular region plated 102 on the opposite side to the patches with positions 104 indicated by the placement of the security screws or the like, whereby the dielectric can be securely secured to a formed back plane of reflection that is not shown.

An important feature of this board is that the radiation element is placed on a front side of the board, whose radiation element acts as a floor plane for the microstrip feed network directly opposite the patch. This distribution provides the isolation for the power network. Alternative radiation patches or elements can be printed on any of the sides of the circuit board according to the detailed antenna design, but this could compromise the efficiency of the radiation elements. This type of power distribution can provide an optimal feeding point location for any polarization. In a polarized dual mode, there is no compromise in cross polar operation.

The shape of the buried reflection plane provides a cavity behind which the width of the antenna band of the operating radiation elements is broadly determined and provides protected distribution cavities that act as a screen for the distribution network (no radiation of microstrips without practical application) and the microstrip - cable transition section and allowing the microstrip network to be located on the back side of the board, thus protecting itself from the effects of the dome. The distance of the floor plane from the microstrip lines is such that the micro wave signals propagate in a microstrip transmission mode as opposed to a tape line transmission mode. This is true for the path of the microstrips that pass between the area of the cavity towards the transition area of the path cable of the microstrip. For a cellular radio antenna, intermodulation operation is critical; thus in this particular case the cables covered with semi-rigid copper are used to be covered with an insulating sleeve that contracts with the heat. These cables work to adapt to the meanders in the retention characteristics of the support plate cable. Both the inside and the outside of the cable are soldered to the circuit board of the antenna. Therefore, this design provides several advantages.

If the radiation elements are patches, then they can be printed using standard dielectric techniques. The patch and the power network can be manufactured in one process. The distance of the patches towards a plane of the reflector floor is a compromise between the width of the band and the restrictions of the space. For certain applications, where a low profile antenna is required, the patch antennas provide good bandwidth. In order to provide a suitable adaptation network without incurring too much loss, a design was established that has a space below the patch with respect to the plane of the reflector floor at 13 mm, for the GSM MHz band, conforming to the element of the antenna and the heat sink units behind it with the protective dome. This depth can be varied for the other frequencies, such as the 1800 and 1900 MHz bands.

Dual polarization can be used to provide a form of diversity. This can be implemented using two polarizations at ± 450. On the receiving side, the diversity of polarization that uses techniques as a maximum proportion combining techniques (other types of combination are possible) helps to overcome the spread of discoloration. The transmitting pattern can be fed by feeding to a second azimuth element in the anti-phase and at a reduced amplitude. If two patches are used they should be placed closely adjacent to each other to avoid too great a dip on the side of the azimuth pattern. For one mode, a separation distance of approximately 0.7 1 was chosen, which provided a bandwidth of 100 'with a 3 dB immersion.

Figure 4 shows a perspective view, an example of a molded floor plane, suitable for use with the antenna shown in Figure 3. The size and shape of the features are determined by the mechanical and electrical requirements of the antenna. In the example shown, two large circular depressions 108 and 110 are formed to provide a suitable support cavity for the two patch elements 78 and 80 that are shown on the circuit board in Figure 3. The depth of these depressions it is firmly controlled according to the electrical requirements of the patch design. A second important feature printed on the sheet are the cavities 109 and 11 whose depth is also controlled.

These two features serve to provide a cover for the microstrip feeding webs Fl, F2 shown in Figure 4. Additional depressions in the support plane provide an integral feeding cable that is retained and a relief structure of tension. The depth of the pressure in this area is made to adapt the outer diameter of the cable plus any insulating protection material. The depths of the structure in each of the areas shown may be different depending on the detailed implementation. In the particular implementation shown, the depths of the retention areas of the cable and the areas of the adaptation network were made identical for ease of the tools. The areas of the cavity have a greater depth than is needed to meet the electrical performance requirements of the antenna. The edges of the support plate were formed orthogonally with respect to the plate to provide additional mechanical stiffness. The drawing shown is for a flat antenna structure, but nevertheless, the antenna support plate can easily be formed to conform to the shape of the front cover of either a simple or double curvature.

The small holes 107 in the center of the depression in the support plate are sealed with a semi-permeable membrane such as the GORTEX RTM to allow the assembly to breathe and prevent condensation within the antenna. Using the common characteristics suitable to provide the alignment, the three main structural parts of the unit are pressed and joined together with an appropriate seal. After the support plate is assembled, the significant structural hardness of the front cover is provided making the whole assembly extremely resistant and capable of withstanding significant impact loads. The bearing plane also provides the mechanical force directly to the printed layer and the dome, and may contain an integrated cable path and strain relief. The openings are provided (not shown) to access the cavity by means of the cables. The integrated assembly takes the radiation elements of the antenna to be in close contact with the dome, avoiding problems with the tolerances to the spaces and the entry of moisture.

The formed back cover plate provides features to act as cavities for the elements of the patch antenna, a cover to protect the supply network, both from the environment and the electrical interference. The assembly of the former in this way provides an integral rigid structure, without metal / metal contacts that can generate intermodulation products.

Referring now to Figure 5, a plan view of the support plane of the antenna 106 is shown as shown in Figure 4, with Figures ßa, ßb, and ßc being cross sections through Figure 5 as along lines C - C 1, BB 'and EE, respectively. The circular depressions 108 and 110 form the cavities behind the patches 78 and 80. The rounded edges 112 provide the transition from the reflection portions to the areas that contact the dielectric. The plane of support preferably presses the aluminum foil having a thickness typically of about 1-2 mm. This thickness affects the radius of the cavities. As can be seen, the depressions provide convenient protection areas for the microsuccess feeding networks. The depth of the cavity provides an increase in the width of the band, while the non-bulged parts offer mechanical support.

Referring now to Figures 7 and 8, there is shown a plan view and a cross sectional view (through X -X ', of Figure 7) of a first embodiment made in accordance with the invention. The patch antenna 30 comprises a patch 32, supported on a first side of a dielectric 34. A microstrip feed 36 is printed on the other side of the dielectric and is in contact with the patch by means of a plated path 38 or Similary. The patch of preference is placed at a distance from a plane of the reflection floor 40, as shown. The signals are fed to the patch via the power supply line of the wave 36 in a microstrip mode of the transmission, with the patch 32 acting as a floor with respect to the line of the microstrip, when the line of the microstrip is located. opposite the patch. The line of the microstrip 36 is protected from radiation and causes interference when it is not opposite the patch by means of the protective floor 42, which is a molded part of the reflector plane 40. The line of the microstrip is fed from a The cable and the line of the microstrip will be in such a way that it provides a suitable adaptation circuit between the cable and the patch, with respect, in other things, to the dielectric constant of the board and the space of the dome. Typically the cable is a semi-rigid coaxial cable and soldered to a hole where it contacts the metal of the microstrip, which is typically made of a copper alloy. For a patch of diameter of 150 mm, the cavity below the patch in the support plane of the grounded reflector would be approximately 160 mm, with the space between the patch and the support plane being around 30 mm.

Figures 9 and 10 show a quadrant of a second embodiment in the plane and cross sectional views (through YY ') of Figure 9). The dielectric 48 is a four-layer board having a patch antenna 50 on a first (top) layer, floor planes 52, 54 on the outer areas of the patch, on the fourth and second layers and a micro / line of tape (buried layer) 56 cover and in this way there is no radiation between the two floor planes, protected from the effects of the dome and the environment. The tracks 58 provide a power and mode suppression means for feeding between the microstrip line and the patch. A reflection support plane 60 is provided, which is connected to a floor by direct contact to the lower floor plane. A limit 62 can be defined between the patch and the floor plan.

Figures 11 and 12 show still a further embodiment, again the plane and the cross sectional views (the cross section is through ZZ in Figure 11). In this embodiment which includes a circular patch 64 printed on a simple dielectric 66, the feed of the microstrip 68 continues only for a short distance on the opposite side of the dielectric in relation to the patch. The tracks 70 are provided to transfer the signals from the micro-wave from the input line of the microstrip 72 to the feed line of the microstrip at the lower side 68. For convenience, the upper microstrip towards the transition of the lower microstrip is made in the region between the plane of the floor 74. Again, a reflector plane 7ß is also present. The floor plane 74 is provided to secure the microstrip transmission mode for the microstrip line 72. A portion of the additional floor plane to protect the microstrip line fields above the dielectric could be appropriate .

Claims (10)

1. An antenna comprising a dome, a dielectric substrate having a radiation element of the antenna on a surface thereof and a reflector support plane providing a reflection cavity behind the radiation element: wherein the dome is directly joined to an outer surface of the dielectric and the plane of support of the reflector is attached to the back surface of the dielectric substrate.

2. An antenna according to claim 1, wherein the radiation element is printed on a first side of the dielectric substrate; where the dome is attached directly to the surface of the dielectric that supports the elements of the printed antenna.

3. An antenna according to claim 2, wherein the plane of support of the reflector is directly connected to the dielectric substrate.

4. An antenna according to claim 2, wherein the radiation element is connected through the substrate to a feed line of the microstrip, whereby the feed line of the microstrip falls parallel to the patch with the radiation element acting as a floor in relation to the line of the microstrip.

5. An antenna according to any of claims 1 to 4 wherein the radiating element is either a rectilinear or ellipsoidal patch.

6. An antenna according to claim 5, wherein the patch has one or more feeds.

7. An antenna according to any of claims 1 to 6, wherein the protective floor is placed on the surface of the dielectric opposite the surface supporting the radiation element, whereby the radiation and the plane of the floor cover a microstrip power line and the distribution network.

8. An antenna according to any of claims 1 to 7, wherein the support plane includes a cavity of the reflector and encloses the supply network for the radiation elements.

9. A method for the operation of an antenna comprising a dome, a dielectric substrate having a radiation element of the antenna on a surface thereon and a support plane of the reflector providing a reflection cavity behind the radiation element; wherein the dome is attached directly to the outer surface of the dielectric and the plane of support of the reflector is attached to the back surface of the dielectric; the antenna is connected through the substrate to a radio frequency feed line, where the antenna transmits and receives signals via the power network.

10. A method according to claim 9, wherein the radiation element is connected through the substrate to a microstrip feed line, whereby the feed line of the microstrip falls parallel to the radiation element, with the radiation acting on a floor with respect to the line of the microstrip. SUMMARY OF THE INVENTION The present invention relates to the integral antenna assemblies and in particular relates to an integral antenna assembly for the microcellular base stations and the wireless fixed access base stations; feeding mechanism for them. In accordance with one aspect of the invention, there is provided an integral antenna comprising a dome, a layered antenna and a reflector support plane, wherein the layers have an outer surface and a back surface; wherein the dome is attached directly to an outer surface of the antenna; and wherein the support plane provides a reflection cavity and encloses the supply network for the antenna and is attached to the back surface of the antenna. According to another aspect of the invention, the method of operation of an integral antenna comprises a dome, a dielectric substrate having a patch antenna element on a surface thereof and a support plane of the reflector providing a reflection cavity. behind the radiation element; wherein the dome is attached directly to an outer surface of the dielectric and the plane of support of the reflector is attached to the back surface of the dielectric; the patch is connected through the substrate to a feeding line of the microstrip, with which the feeding line of the microstrip falls parallel to the patch, with the patch acting as a floor with respect to the line of the microstrip, in where the antenna transmits and receives signals via the power network.