ES2842108T3 - An adaptive antenna array and an apparatus and method for feeding signals to an adaptive antenna array - Google Patents

Abstract

A feeding device for supplying a radio frequency signal to a set of adaptive antennas comprising a plurality of antenna elements, said feeding device comprising: a plurality of signal dividers (1), each of said signal dividers (10) comprising : an input port for receiving said radio frequency signal, an output port, an additional output port and a variable impedance; wherein said signal divider is configured to divide said input signal and direct said divided signals toward said variable impedance (20); said divided signals are at least one of that reflected to said output port and transmitted to said additional output port, said degree of reflection and transmission depending on a value of said variable impedance (20), said degree of reflection being variable and transmission between substantially all reflection and substantially all transmission; wherein said signal splitter is configured such that phase shifts are introduced to signals traveling between ports, said phase shifts being such that said divided signals received at said output port and said additional output port constructively interfere and signals received at external ports of said signal splitter other than said output ports are out of phase and destructively interfere; said output and said additional output ports of at least one of said at least one signal splitter are configured to supply signals to respective antenna elements of said set of antennas; wherein said plurality of signal dividers (10) are arranged in a cascade, said cascade comprising: an input signal divider configured to receive said radio frequency input signal and direct said signal to at least one of said output port and said additional output port of said input signal splitter; additional signal dividers each configured to receive at an input a signal from one of said output port and said additional output port of one of said signal dividers at a higher level of said cascade; and a plurality of output signal splitters each being configured to direct an input signal received through at least one of said output port and said additional output port to respective antenna elements (30) of said array of antennas.

Description

DESCRIPTION

An adaptive antenna array and an apparatus and method for feeding signals to an adaptive antenna array

Field of the invention

The present invention relates to feeding signals to adaptive antenna arrays and to these adaptive antenna arrays.

Background

Antenna arrays have been widely used in telecommunications because of their ability to: focus RF signals to a specific sector and to use MIMO techniques to improve coverage and capacity.

In many beamforming / MIMO applications, it is advantageous if the antenna / antenna array can be reconfigured so that not only can they provide a narrow beam of RF power to a particular user or a particular set of users, but they can also provide wide RF coverage to a larger number of users.

Adaptive beamforming / shaping can be achieved in the RF domain or in the digital domain. Digital approaches offer full flexibility, however, at increased cost and energy consumption. Alternatively, adaptive beam reconfiguration in Rf can be achieved, ie by turning selected antenna elements on or off depending on the required beam. In this case by turning off elements, an assembly is provided which operates with reduced elements resulting in a wider beam at reduced power cost along the main beam. This can be extended to the case where all but one antenna elements are turned off, resulting in maximum angular coverage while limiting the range along the radial direction. One limitation with such an approach is that turning off the antenna elements is typically implemented using an absorbent switch which reduces energy efficiency since power is dissipated in the feed network as heat.

The reason these absorption mechanisms are used in general is that any reflection of RF power significantly deteriorates the performance of the overall system. For example, RF power reflection is particularly detrimental to an RF Power Amplifier and can cause it to exhibit unstable behavior that would lead to complete system breakdown.

Figure 1 shows an example of the previous concept. In this example, a network comprising power splitters / dividers is used to distribute the input RF signal to individual antenna elements. Generally these splitters / dividers are not variable and either provide a signal or they turn off and the signal is absorbed by the resistor.

Obtaining a large power division ratio in a power splitter is not an easy task and because of this and the problems that arise in such systems where reflected signals are transmitted back to the input, a solution that uses an absorber switch added at the output of the power distribution network with the aim of selectively deactivating the signal feed to a particular antenna element and avoiding reflections of the signal.

A major disadvantage of this prior art approach is that by absorbing RF power rather than reflecting it, valuable RF power is wasted as heat. It would be desirable to selectively direct a signal to one or more elements of an array of antennas while maintaining energy efficiency and providing flexibility.

Document EP2698870 discloses an antenna feed where Wilkinson power dividers are used that separate the signal in different ratios to supply phase shifting elements and then hybrid couplers where some phase shifted signals are recombined before feeding antenna elements into an array. of antennas to provide a desired beam shape.

"A Novel Variable Power Divider with Continuous Power Division" by Bulja and Grebennikov in Microwave and Optical Technology Letters vol. 55 no.7 pp. 1684 - 1686, July 2013) discloses a variable power divider in the form of a 3 dB coupler in the context of supplying power to Doherty amplifiers

Document WO2004 / 038452 discloses a beamforming means in an array of antennas where the loads in the feed path of each antenna element are varied using varying impedances, for example, which generate reflections.

Summary

A first aspect of the present invention provides a feed device for supplying a radio frequency signal to a set of adaptive antennas comprising a plurality of antenna elements, said feed device comprising: a plurality of signal dividers, each of said dividers comprising signal: an input port to receive said radio frequency signal, an output port, an additional output port and a variable impedance; wherein said signal divider is configured to divide said input signal and direct said divided signals toward said variable impedance; said divided signals are at least one of that reflected to said output port and that transmitted to said additional output port, said degree of reflection and transmission depending on a value of said variable impedance, said degree of reflection and transmission being variable between substantially all reflection and substantially all transmission of said signal; wherein said signal splitter is configured such that phase shifts are introduced to signals traveling between ports, said phase shifts being such that said divided signals received at said output port and said additional output port constructively interfere and signals received at external ports of said signal splitter other than said output ports are out of phase and destructively interfere; said output and said additional output ports of at least one of said at least one signal splitter are configured to supply signals to respective antenna elements of said set of antennas; wherein said plurality of said signal dividers are arranged in a cascade, said cascade comprising: an input signal divider configured to receive said radio frequency input signal and direct said signal to at least one of said output port and said port additional output of said input signal divider; additional signal dividers each configured to receive at an input a signal from one of said output port or said additional output port of one of said signal dividers at a higher level of said cascade; and a plurality of output signal splitters each configured to direct an input signal received through at least one of said output port and said additional output port to respective antenna elements of said array of antennas.

The inventors of the present invention recognized that the transmission and reflection of radio frequency signals are two processes that are dependent on impedance in the circuit and this dependence could be used to selectively direct a signal to one or more outputs. In general, power dividers that can cause signal reflection in antenna feeder assemblies have been avoided as reflected signals can significantly reduce performance. However, the inventors recognized that the problems associated with signal reflection in antenna feeders could be mitigated if signals were split and then recombined so that the signals interfere with each other. With proper selection of components and / or path lengths, constructive interference could be provided between split signals arriving at the desired outputs, while destructive interference between these signals could be achieved at other external ports, which would later avoid or at least reduce reflected signals. unwanted that impair performance.

In this way, a variable impedance can be used to control the degree of reflection and transmission of a signal that provides a controllable, efficient, and low-loss way of transmitting a signal to one output port, or reflecting the signal to another. port, or of both reflection and transmission of different portions of the signal as desired.

With proper selection of impedance values, substantially complete reflection and substantially complete transmission of the signal can be achieved. In this way, one or the other of the output ports can be selected and the entire signal transmitted or reflected to that output port. With an impedance choice somewhere between these two limit values, a portion of the signal and a reflected portion can be transmitted, the degree of transmission or reflection depending on the impedance value. This allows the amplitude of the signal transmitted to the multiple antenna elements to be precisely and easily controlled.

In some embodiments, said feeding device comprises control logic configured to control a value of said variable impedance to control said degree of reflection and transmission.

Given the controllable nature of the at least one signal divider, it may be advantageous if the feeding device has control logic that allows it to control a variable impedance value and thus control the degree of reflection and transmission. This allows the control logic to control the amplitude of the signal transmitted to each antenna element and this can be used to provide desired beams and allows the antenna array to be flexible and configurable.

In some embodiments, said at least one signal splitter comprises: a directional device comprising said input port, said output port, and two additional ports; an additional directional device comprising two ports each in data communication with a respective one of said two additional ports of said directional device, and an additional output port, said impedance varying between said two additional ports and said two ports; wherein said signals received in each of said two additional ports are at least one of the one reflected to said output port of said directional device and the one transmitted to said additional output port of said additional directional device, said degree of reflection depending and transmission of a value of said variable impedance.

Although the signal splitter can be configured in a number of ways that make use of the properties of Reflection and transmission of a radio frequency signal depending on the impedance and constructive and destructive interference to control the signal amplitude, in some cases, devices are used that are directional to each other, the variable impedance being located between the ports of the two devices. Changes in variable impedance affect whether the signal is transmitted between the two devices or whether it is reflected back to the output port on the first device.

In some embodiments, said directional devices comprise quadrature couplers comprising four ports, directing paths between adjacent ports of said quadrature coupler that introduce a 90 ° phase shift to signals that travel directly between said ports.

One way the signal splitter could be implemented is by using quadrature couplers that have four ports with direct paths between adjacent ports that introduce a 90 ° phase shift. This 90 ° phase shift can be used with care by directing signals such that signals arriving at ports where a signal should not be output have a 180 ° difference in phase and as such destructively interfere, while those arriving at the ports where the signals are to be broadcast have substantially no phase difference between them and, as such, interfere constructively.

In some embodiments, said directional devices comprise 3 dB couplers.

3 dB couplers are particularly suitable for use as directional devices that provide the desired phase shift between input and output signals and that allow the user, with careful choice of impedance values, to select whether to reflect and / or transmits a signal or a particular portion of a signal.

In some embodiments, said at least one signal divider comprises two variable impedances with each of said divided signals being directed to one of said two variable impedances.

The signal divider may require two variable impedances with each of the divided signals directing to one of them. Therefore, once the signals are divided they are directed to each of a separate variable impedance and consequently reflected and / or transmitted,

In some embodiments, said two variable impedances are varied in the same way to have the same impedance.

Although it would be possible for the two variable impedances to have different values, it may be advantageous for them to be varied in the same way, so that they have the same value as this enables the signals to be matched and the destructive interference to be substantially canceled. of the signal that reaches the external port where you do not want it to be emitted.

In some embodiments, said at least one signal splitter comprises a fourth port, being out of phase and destructively interfering with signals received from said signal splitter at said fourth port and said input port.

In many signal splitter implementations there may be a fourth port since these splitters can be symmetrical. When this is the case, to avoid the requirement for an absorption resistor to absorb the signal and avoid reflection of the signal, it is advantageous if the signals arriving at the fourth port are out of phase with each other and thus canceled by destructive interference. This avoids the need for an absorbing switch and enables signals to be recirculated rather than absorbed, increasing the energy efficiency of the device.

Although when only two antenna elements are fed a single signal splitter can be used, it is envisaged to have a plurality of signal splitters and these are arranged in a cascade such that a first input signal splitter receives the signal and outputs it to two additional signal dividers which in turn output the signal to four outputs that can be further transmitted to four additional signal dividers. In some cases, these signal splitters may be arranged in an array so that the final row of the signal splitter comprises a number of outputs that is a power of 2. However, when a different number of antenna elements is desired, then the cascade can be formed with some emitted signals traveling through a number of signal dividers and other emitted signals traveling through a different number of signal dividers. In this way, any number of outlets can be provided. Additionally, the amplitude of the signal transmitted to each antenna element can be controlled by controlling the varying impedances of the different signal dividers.

In some embodiments, said control logic is configured to independently control said variable impedance of each of said signal dividers to control the signal transmitted to each of said antenna elements.

When there are multiple signal dividers, the control logic is advantageously configured to control independently the variable impedance of each of the signal dividers and thus control the signals transmitted to each of the transmitter elements.

In some embodiments, said control logic is configured to control said signals transmitted to said antenna elements such that said set of antennas emit selected beam patterns, said control logic being configured to: determine a weight of each antenna element to generating said selected beam patterns; determining values of said variable impedances required to provide a signal of a required weight to each of said antenna elements; and controlling said variable impedances of each of said signal dividers so that said signals of said required weight are fed by said feed device to said antenna elements.

The power network device is especially suitable for configuring desired beam shapes for an array of antennas. In this sense, when certain beam patterns are required, this information is provided to the control logic that determines the weight of each antenna element of the set of antennas that is required to generate such a beam pattern. Once this is determined, you can calculate the values of the variable impedances required to provide the signals of the required weight for each of the antenna elements and subsequently, the control of the variable impedances provides the desired signals to the antenna elements and the desired beam pattern is formed. Therefore, a highly controllable adaptive assembly is provided that can produce required beam patterns where the input signal is recirculated around the power network with low dissipation allowing the beams to be configured on a dynamic basis in an efficient way. Energy.

A second aspect of the present invention provides an adaptive antenna array comprising: a plurality of antenna elements arranged in an array; a transceiver for receiving and transmitting a signal from and to said set; and a feeding device according to a first aspect of the present invention.

A third aspect of the present invention provides a method of controlling signals transmitted by a feed device to provide selected beam patterns in a set of adaptive antennas, the feed device comprising a plurality of signal splitters arranged in a cascade, each comprising of said signal dividers an input port to receive a radio frequency signal, an output port, an additional output port and a variable impedance, wherein said signal dividers are each configured to divide said input signal and direct said divided signals towards said variable impedance, said divided signals are at least one of the one reflected to said output port and the one transmitted to said additional output port, said degree of reflection and transmission depending on a value of said variable impedance, and being variable between substantially all reflection and substantially all transmission of said signal, wherein said cascade of signal dividers are arranged so that at least one input signal divider receives an input radio frequency signal and divides and directs said divided signal to at least one output and from there to additional signal dividers, each of the signal dividers being configured to direct an input signal received through at least one of said output port and said additional output port to respective antenna elements of said set of antennas, said method comprising : determining a weight of each antenna element in said set of antennas required to generate said selected beam pattern; determining values of said variable impedances in each signal divider required to provide a signal of a required weight to each of said antenna elements; and generating control signals to control said variable impedances of each of said signal dividers so that said signals of said required weight are fed by said feed device to said antenna elements.

Aspects of the invention can be used to determine the signals required at each antenna element required to provide the desired beam pattern and to provide control signals to vary the varying impedances of the power network signal dividers to provide the signals. required. The feeder device controlled by such a method may be the feeder device according to a first aspect of the present invention.

A fourth aspect of the present invention provides a computer program operable when executed by a processor to control said processor to perform a method in accordance with a third aspect of the present invention.

In some embodiments the computer program may be part of the control logic that controls the feeder device of the first aspect of the present invention.

Additional preferred and particular aspects are set forth in the attached independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set forth in the claims.

Where an appliance feature is described as being operable to provide a function, it will be appreciated that this includes an appliance feature that provides that function or is adapted or configured to provide that function.

Brief description of the drawings

Embodiments of the present invention will now be further described, with reference to the accompanying drawings, in which:

Figure 1 illustrates a set of four switched antenna elements in accordance with the prior art; Figure 2 shows a feeder circuit for an antenna array according to one embodiment;

Figure 3 shows a signal splitter for use in one embodiment;

Figure 4 shows a feeder circuit according to a further embodiment; Y

Figure 5 shows a set of adaptive antennas, power network and control circuitry according to one embodiment.

Description of the achievements

Before discussing the embodiments in any further detail, an overview will first be provided.

The embodiments seek to use the reflection and / or transmission of a radio frequency signal that can occur due to changes in impedance in the circuit, to selectively make reflections and / or allow transmissions of a signal to cause the signal to be delivered. selectively to multiple antenna elements. A plurality of signal dividers are used that direct input signals to particular or multiple outputs. These signal dividers recirculate reflected signals to outputs, thereby improving energy efficiency. By locating an output on the reflected signal path and an additional output on the transmitted path, the signal can be directed to one, the other, or both of the output ports, with the choice of the amount of the signal and the port of output by varying the impedance and thus the degree of transmission and reflection. This is an effective and efficient way of selecting outputs that does not require an absorbent switch.

When the impedance is in parallel with the transmission line, then a substantially infinite impedance causes substantially all of the radio frequency signal to be transmitted and virtually none of the reflected signal which means that the signal is output to the additional output. When a zero impedance is provided, which in effect grounds the transmission line, then the signal is reflected and output. Any impedance value between these two values provides some reflection and some transmission so that the signal is output at both the output and the additional output. When the output and the additional output are connected to antenna elements then the antenna element or elements receiving a signal can be selected.

Additionally, signal separation and the choice of phase shift between ports allows the divided signals transmitted to the output ports to be in phase and provide constructive interference and increase the energy efficiency of the device. Other signals transmitted to the other external ports such as the input port are out of phase due to the design of the signal splitter and interfere destructively reducing any unwanted reflected signals in the system.

In effect, by providing routes with different phase shifts between elements and directing appropriately split signals, signals can be directed to an external port by different routes with each route having a particular phase shift, so that the signals constructively interfere or interfere. destructively. When split signals are matched, destructive interference can effectively eliminate the signal by eliminating the need for an absorbing switch.

Indeed, a lossless or at least low loss solution is proposed for adaptive beam reconfiguration in RF.

In particular, a distributed power network is disclosed for distribution of RF power to multiple antenna elements with reduced energy loss. The performance of this network is characterized by large power division ratios, and the absence of absorption switches.

Figure 2 shows a feed network comprised of a cascade of flexible non-absorbent power dividers 10 (shown in more detail in Figure 3) that are arranged to feed multiple antenna elements 30. Beam reconfiguration is achieved using the splitters. power 10 by varying the admittance values of the variable impedances 20 in the network. Variation in the admittance values of the varying impedances 20 varies the amount of the signal that is reflected and the amount that is transmitted. This amount varies between substantially all or none so that the signal can be sent to a selected single of the two outputs (port 3 and port 4 of Figure 3) or portions of the signal can be separated and sent to both ports. In this way, by varying the admittance values of the varying impedances, the feed network arrangement recirculates signals with varying amplitude and phase and provides them to antenna elements 30 selected from the array above that provides the desired beams.

Recirculation of the input signal along the power network allows what might have been dissipated in one part of the power network to be fed to another part of the network. Therefore, as the beams are configured on a dynamic basis, the energy dissipated due to heat will be at a minimum or at least significantly reduced.

The first stage in the design and control of such an architecture is to estimate the complex weights associated with each antenna element for a specific beam. The second stage is to later map these weights as admittance parameters for the specified architecture.

Consider Figure 2 with N = 2 * m + 1 antennas, the amplitude and phase weights can be designed to produce a main lobe along direction 9 while minimizing or at least reducing the energy radiated through all the other addresses

u ( 8) = max \\ a7 ( 9) ufi) II subjected to minute ( 9) Ra u ( 8) (1,0)

Where

u ( 9) amplitude and phase weights for a given beam

a ( 9) set response for a given angle

R ^a is the response of the global set

One approach to obtain the optimal solution for (1,0) is through the Lagrange multiplier approach. Continuing along the same lines, we can explicitly represent the supply network admittance parameters as a function of u (9) and solve for these parameters. Such optimization ensures that the power network circuitry is optimized or at least improved to reduce loss and obtain desired beam pattern performance. An example of such a design is explained below.

The elemental power divider is shown in more detail in Figure 3. A similar power divider has been disclosed by Bulja and Grebennikov in "A Novel Variable Power Divider with Continuous Power Division" in Microwave and Optical Technology Letters vol. 55 no.7 pp. 1684-1686, July 2013, however, this is in the context of supplying power to Doherty amplifiers where the issues to be addressed are the feasibility of using high impedance lines for asymmetric power separation. In this sense, the use of such a power divider is unique in the context of a power network for a set of antennas. The advantages of such a power divider in an antenna feed assembly is that no, or at least very little, RF power is dissipated at the termination resistor, Rt, and that the input RF power at the Port 1 can be varied depending on the Y admittance value, and can be fully reflected to port 4 or completely transmitted to port 3.

The principle of operation of the power separator of Figure 3 is described below. The input RF signal from port 1 is separated into two quadrature components, depending on the admittance value Y, reflected / transmitted completely or partially at intermediate ports 12 and 14 towards ports 3 and 4, respectively. In other words continuous power division is obtained and RF power is not wasted during division operation. Of course, some RF power is lost to circuit clutter, but no RF power is intentionally burned to perform this operation. Port 2 and port 1, by means of a 3 dB coupler, remain isolated regardless of the admittance value Y.

In this sense, the signal that arrives at port 12 from the input port has a phase shift of 90 ° while the signal that arrives at port 14 has a phase shift of 180 °, when reflected in ports 12 and 14 , the reflected signal from port 12 to the input has an additional phase shift of 90 ° while that of port 14 has an additional phase shift of 180 °, therefore the signals arriving at the input of port 12 have a 180 ° phase shift, while those at port 14 have a 360 ° phase shift, the signals at the input port are therefore out of phase and the input port is shielded from these reflected signals. Signals arriving at port 4, in contrast, experience an additional 90 ° phase shift from port 14 and an additional 180 ° phase shift from port 12, therefore each signal has a phase shift of 270 ° when it reaches port 4 and constructive interference occurs and the two signals are combined and emitted.

Similar phase shifts occur with signals transmitted through the second 3 dB coupler such that destructive interference occurs on port 2 and constructive interference occurs on port 3.

Now, using the circuit of Figure 3 as a constituent element, it is possible to obtain by the unit power divider cell of the antenna feed network almost any power division of the input RF signal. In particular, this means:

The input RF signal can be separated into almost any power division ratio - the limiting case is with the switching of some antenna elements completely off.

This will have no power loss or minimum of r F in the event of turning off desired antenna elements. In in this case, the RF power will be redistributed among the remaining "on" antenna elements.

Figure 4 shows an alternative embodiment of the proposed power network, where the power separator elements are mirror images of each other. This can be advantageous when the devices are built in silicon, this design makes them more compact.

Figure 5 shows schematically a set of adaptive antennas 50, with a power network 5 and control logic 40 according to one embodiment. The adaptive antenna assembly 50 comprises a plurality of antenna elements 30 supplied with signals from a network feed assembly 5 comprising signal dividers 10 arranged in a cascade arrangement. Each signal divider has two outputs and one input. The outputs of the output signal dividers supply signals to respective antenna elements 30.

Each signal divider 10 has a controllable variable impedance 20, the impedance value of which is controlled by signals emitted by control logic 40. The control logic 40 is aware of the antenna architecture assembly and receives signals indicative of the beam pattern that must be emitted by the set of antennas 50. It then calculates weights for each of the antenna elements 30 to provide the required beam pattern, from this it calculates the signals that must be supplied to each antenna element 30 to generate the pattern beams and the corresponding impedance values required in the signal dividers 10 to provide the appropriate signals to the individual antenna elements 30. It then generates and transmits control signals to control these impedances and the signals supplied to the antenna elements are appropriately weighted and the required beam pattern is output.

Analysis

Analysis of the power divider of Figure 3

The matrix of S parameters of the circuit of Figure 3 is

' 0 0 s13 S14]

0 0 S23 S24

[S] = S31 S32 0 0 (1)

ls 41 S42 0 0 J

where,

In (2) and (3), T ^s and R ^s represent the transmission and reflection coefficients, while Z ^o is the characteristic impedance of the interconnecting transmission line. It can be shown that, if the admittance Y of the varactor diode is purely imaginary, the power conservation condition is satisfied, that is

The last two cases are established for Ts and Rs when admittance Y is allowed to be either 0 or infinity. For the case when Y = 0, (2) and (3) becomes

Ts (Y = 0) = j and Rs = 0 (5)

While in the case of Y infinite

Ts (Y ^ «) = 0 and R ^s (Y ^«) = -j (6)

(5) and (6) infer that by manipulating the admittance Y it is possible to obtain perfect distribution of input RF power between the reflected ports, R ^s , and transmitted, T ^s . To be specific, admittance Y can be used to control the lossless division of the input power between the two output ports. From (5) and (6) it can be seen that to achieve the lossless dynamic power division, the admittance Y must be imaginary, and variable from - ~ to ~. This condition is well known in the design of 360 ° reflection type phase shifters and the principles of this design can easily be applied in the present circuit.

Analysis of the proposed power network in Figure 2

The transmission coefficients for the antenna elements, indicated from 0 to 2m-1 are

or: S21 = RiiR2i ... Rm, i

1: S3i = Rii R21 ... Tm, i (7)

puede observarse que las salidas del elemento de antena siguen el sistema de numeración binario, siendo Rm,n un 0 lógico y siendo Tm,n un 1 lógico.with

It can be seen that the outputs of the antenna element follow the binary numbering system, with Rm, n being a logical 0 and Tm, n being a logical 1.

The system of equations given by (7) contains 2m equations, while the number of unknown admittances, Ym, n is equal to 2m-1. However, the system of 2m equations given by (7) is not linearly dependent and the antenna outputs given by (7) need to satisfy a principle of conservation of power, i.e.

pérdida (8)

loss (8)

The last term in (8) indicates the contribution of the overall system loss, which is normally known. Now, (7) and (8) form a linearly independent system of 2m-1 equations, which can be solved unequivocally for Ym, n. The solutions for Ym, n will ultimately depend on the required division of power between the antenna ports.

One skilled in the art will readily recognize that the steps of various methods described above can be performed by programmed computers. In this document, some embodiments are also conceived to cover program storage devices, for example digital data storage media, which are computer or machine readable and encode machine-executable or computer-executable programs of instructions, wherein said instructions perform some or all of the steps of the above-described methods. Program storage devices can be, for example, digital memories, magnetic storage media such as magnetic discs and magnetic tapes, hard drives, and optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform said steps of the above-described methods.

The functions of the various elements shown in the figures, including any functional blocks labeled "processors" or "logic", can be provided through the use of specialized hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions can be provided by a single specialized processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Furthermore, the explicit use of the term "processor" or "controller" or "logic" should not be construed to refer exclusively to hardware capable of running software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, processor network, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read-only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage. Other hardware, conventional and / or custom, can also be included. Similarly, any switch shown in the figures is solely conceptual. Its function can be carried out through the operation of program logic, through specialized logic, through the interaction of program control and specialized logic, or even manually, the particular technique being selectable by the implementer as more specifically understood. from the context.

It should be appreciated by those skilled in the art that any block diagram in this document represents Conceptual views of illustrative circuitry incorporating the principles of the invention. Similarly, it will be appreciated that any flow charts, flow charts, state transition diagrams, pseudo code, and the like represent various processes that can be substantially represented on computer-readable medium and thus executed by a computer or processor, both if such a computer or processor is explicitly shown as if not.

The description and drawings merely illustrate the principles of the invention. The scope of the invention is defined in the appended claims.

Claims (11)

A feed device for supplying a radio frequency signal to an adaptive antenna array comprising a plurality of antenna elements, said feed device comprising: a plurality of signal dividers (1), each of said signal dividers (10) comprising: an input port for receiving said radio frequency signal, an output port, an additional output port and a variable impedance; where said signal divider is configured to divide said input signal and direct said divided signals towards said variable impedance (20); said divided signals are at least one of that reflected to said output port and transmitted to said additional output port, said degree of reflection and transmission depending on a value of said variable impedance (20), said degree of reflection being variable and transmission between substantially all reflection and substantially all transmission; where said signal divider is configured such that phase shifts are introduced to signals traveling between ports, said phase shifts being such that said divided signals received at said output port and said additional output port constructively interfere and the signals received at external ports of said signal splitter other than said output ports are out of phase and destructively interfere; said output and said additional output ports of at least one of said at least one signal splitter are configured to supply signals to respective antenna elements of said set of antennas; wherein said plurality of signal dividers (10) are arranged in a cascade, said cascade comprising: an input signal splitter configured to receive said radio frequency input signal and direct said signal to at least one of said output port and said additional output port of said input signal splitter; additional signal dividers each configured to receive at an input a signal from one of said output port and said additional output port of one of said signal dividers at a higher level of said cascade; Y a plurality of output signal splitters each being configured to direct an input signal received through at least one of said output port and said additional output port to respective antenna elements (30) of said array of antennas. The feeding device according to claim 1, said feeding device comprising control logic configured to control a value of said variable impedance to control said degree of reflection and transmission. The feeder according to claim 2, wherein said control logic is configured to independently control said variable impedance of each of said signal dividers to control control signals transmitted to each of said antenna elements. The feeder according to claim 3, wherein said control logic is configured to control an amplitude of said signals transmitted to each of said multiple antenna elements such that said set of antennas emit selected beam patterns, being configured this control logic to: determining a weight of each antenna element to generate said selected beam patterns; determining values of said variable impedance required to provide a signal of a required weight to each of said antenna elements; Y controlling said variable impedances of each of said signal dividers so that said signals of said required weight are fed by said feeding device to said antenna elements. The feeder device according to any preceding claim, wherein said at least one signal splitter comprises: a directional device comprising said inlet port, said outlet port and two additional ports; an additional directional device comprising two ports each in data communication with a respective one of said two additional ports of said directional device, and an additional output port, said impedance varying between said two additional ports and said two ports; wherein said signals received in each of said two additional ports are at least one of the one reflected to said output port of said directional device and the one transmitted to said additional output port of said additional directional device, said degree of reflection depending and transmission of a value of said variable impedance. The feeder device according to claim 5, wherein said directional devices comprise quadrature couplers comprising four ports, direct routes between adjacent ports of said quadrature coupler that introduces a 90 ° phase shift to directly traveling signals between those ports. 7. The feeder device according to claims 5 or 6, wherein said directional devices comprise 3 dB couplers. The feeding device according to any preceding claim, wherein said at least one signal divider comprises two variable impedances, each of said divided signals being directed to one of said two variable impedances. 9. The feeding device according to claim 8, wherein said two variable impedances are varied in the same way to have the same impedance. The feeder device according to any preceding claim, wherein said at least one signal splitter comprises a fourth port, being out of phase and destructively interfering with signals received from said signal splitter at said fourth port and said port. input. 11. A set of adaptive antennas comprising: a plurality of antenna elements arranged in an array; a transceiver for receiving and transmitting a signal from and to said set of antennas; Y a feeding device according to any preceding claim.