MXPA06004930A - Phased array antenna system with controllable electrical tilt - Google Patents

Abstract

A phased array antenna system with controllable electrical tilt generates two signals V2a and V2b with variable relative delay therebetween. The signals are converted into antenna element drive signals by a power distribution network (100). The network (100) splits each of the two signals V2a and V2b into three signal components. Pairs of components of different signals are input to respective (180) hybrid coupling devices (hybrids) (110, 112 and 114), which provide vector sums and differences of their inputs and act as phase-to-power converters. Their outputs are distributed between further (180) hybrids (116, 118 and 120), which act as power-to-phase converters and provide antenna element drive signals with phase varying both with element array position and also with the variable relative delay between the two signals V2a and V2b. Antenna electrical tilt is therefore controllable by altering a single relative delay.

Description

Declaration under Rule 4.17: For two-letter codes and other abbreviations, refer to the "Guid- - of inventorship (Rule 4.17 (iv)) for US only ance Notes on Codes and Abbreviations" appearing at the begin- ning ofeach regular issue ofthe PCT Gazette. Published: - with International search repon PHASE ARRANGEMENT ANTENNA SYSTEM WITH CONTROLLABLE ELECTRIC TILT The present invention relates to a phase array antenna system with controllable electrical tilt. The antenna system is suitable for use in many telecommunications systems but is especially useful in mobile cellular radio networks, which are commonly known as mobile telephone networks. More specifically, but without limitation, the antenna system of the present invention can be used with second generation mobile telephone networks (2G) such as GSM system, CDMA systems (IS95), D-AMPS (IS136) and PCS, and third generation (3G) mobile telephony networks such as the Telephony System Universal Mobile (ÜMTS, for its acronym in English), and other cellular systems. Operators of cellular mobile radio networks generally employ their own base stations, each of which has at least one antenna. In a cellular mobile radio network, the antennas are a primary factor in defining a coverage area where communication with the base station can be made. The coverage area is generally divided into several cells, each one associated with a respective antenna and base station. Each cell contains a base station for radio communication with all mobile (mobile) radios in this cell. Base stations are interconnected by means of communication, usually fixed land lines, or radio links from point to point, allowing mobile radios throughout the cell coverage area to communicate with each other as well as with the public telephone network outside. of the cellular mobile radio network. Networks of cellular mobile radios are known that use antennas of arrays in phase; said antenna comprises an array (usually eight or more) of individual antenna elements such as dipoles or patches. The antenna has a radiation pattern that incorporates a main lobe and side lobes. The center of the main lobe is the maximum sensitivity antenna direction in reception mode and the direction of its main output radiation beam in transmission mode. It is a well-known property of a phase array antenna that if signals received by the antenna elements are delayed by a delay that varies according to the distance of the elements of an array edge, then the main antenna radiation beam is directed towards the direction of increasing delay. The angle between the centers of main radiation beams corresponding to zero and a non-zero variation in delay, that is, the angle of inclination, depends on the rate of delay change with the distance in the array. A delay can be implemented in an equivalent manner by changing the signal phase, hence the expression phase array. The main beam of the antenna pattern can therefore be altered by adjusting the phase relationship between signals fed to antenna elements. This makes it possible to direct the beam in order to modify the coverage area of the antenna. Operators of phase array antennas in cellular mobile radio networks have the requirement to adjust the vertical radiation pattern of the antennas, that is, the cross section of the pattern in the vertical plane. This is necessary in order to alter the vertical angle of the main antenna beam, which is also known as the "tilt" in order to adjust the coverage area of the antenna. Such adjustment may be required, for example, to compensate for the change in cellular network structure or the number of base stations or antennas. The adjustment of the angle of antenna inclination is known both mechanically and electrically, either individually or in combination. The angle of antenna inclination can be adjusted mechanically by moving the antenna elements or their frame (randome): it is preferable to adjust the angle of "mechanical inclination". In accordance with what is described above, the antenna tilt angle can be adjusted electrically by changing the delay time or phase of signals that are fed to each antenna array element (or element group) or received from each element of antenna. antenna arrangement (or element group) without physical movement: this is known as the adjustment of the "electrical tilt" angle. When used in a cellular mobile radio network, the vertical radiation pattern of the phase array antenna (VRP) has several significant requirements: 1. high physical axis gain; 2. a first level of upper side lobe sufficiently low to avoid interference with moving radios using a base station in a different cell; 3. a first lower side lobe level high enough to allow communications in the immediate vicinity of the antenna; 4. levels of lateral lobes that remain within predetermined limits when the antenna is electrically inclined. The requirements are mutually conflicting, for example, the increase of the physical axis gain can raise the level of the lateral lobes. Also, the direction of the level of the lateral lobes can change when the antenna is electrically inclined. A first maximum level of the upper lateral lobe, in relation to the level of the physical axis, of -18 dB offers a convenient compromise in relation to the overall development of the system. The effect of adjusting either the mechanical tilt angle or the electric tilt angle is to replenish the physical axis of a directional antenna so that, for an arrangement that is in a vertical plane, point either up or down the horizontal plane, and therefore change the coverage area of the antenna. It is desirable that both the mechanical inclination and the electrical inclination of a cellular radio base station antenna can vary: this allows maximum flexibility to optimize cell coverage, since these tilting shapes have different effects on ground coverage of antenna and also on other antennas in the immediate vicinity of the station. Likewise, operational efficiency is improved if the electric tilt angle can be adjusted remotely from the antenna assembly. While a mechanical antenna tilt angle can be adjusted by repositioning its antenna, changing its electrical tilt angle requires an additional electronic circuit that increases the cost and complexity of the antenna. Also, if a single antenna is shared among several operators, it is preferable to provide a different angle of electrical tilt for each operator. The need for an individual angle of electrical tilt from a shared antenna has so far resulted in compromises in relation to the performance of the antenna. The physical axis gain of a directional antenna decreases in proportion to the cosine of the angle of inclination due to a reduction in the effective aperture of the antenna (this is unavoidable and occurs in all antenna designs). In addition, reductions in the physical axis gain of a directional antenna can result from the method used to change the angle of inclination. R.C. Johnson, Antenna Engineers Handbook, Third Edition 1993, McGraw Hill, ISBN 0-07- 032381-X, Chapter 20, Figure 20-2 discloses a known method for locally or remotely adjusting an antenna electrical tilt angle of phase arrays. In this method, a carrier signal of radio frequency (RF) transmitter is fed to the antenna and distributed to the antenna irradiation elements. Each antenna element has a respective phase changer associated with it in such a way that the signal phase can be adjusted as a function of the distance through the antenna to vary the electric tilt angle of the antenna. The power distribution to the antenna elements when the antenna is not inclined is provided in such a way that the level in the lateral lobe and physical axis gain is adjusted. An optimal control of the angle of inclination is obtained when the phase front is controlled for all angles of inclination in such a way that the level of lateral lobe does not increase in the range of inclination. The electric tilt angle can be adjusted remotely, if required, by using a servomechanism to control the phase changers. This antenna of the prior art method has several disadvantages. A phase changer is required for each antenna element. The cost of the antenna is high due to the number of phase changers that are required. A cost reduction by applying delay devices to respective groups of antenna elements instead of individual elements raises the side lobe level. A mechanical coupling of delay devices is used to adjust delays, but it is difficult to do it correctly; In addition, mechanical links and gears are required resulting in a non-optimal distribution of delays. The upper lateral lobe level rises when the antenna is tilted downward thereby causing a potential source of interference with moving radios that use other cells. If the antenna is shared by several operators, the operators have a common electrical tilt angle instead of different angles. Finally, if the antenna is used in a communication system that has uplink and downlink at different frequencies (frequency division duplex system) (which is common) the electrical tilt angles in transmission and reception modes are different. Patent Applications PCT / GB2002 / 004166, PCT / GB2002 / 004930, GB0307558.7 and GB0311371.9 describe different approaches for locally or remotely adjusting an antenna electrical tilt angle through a phase difference between two fed signals to an antenna circuit. PCT / GM2004 / 001297 refers to the adjustment of an electrical tilt by dividing a carrier signal into two signals, varying the phase of one signal relative to the other and applying a phase-to-power conversion to the resulting signals. The converted signals are divided and subjected to a power-to-phase conversion to supply antenna elements. An electrical tilt is adjusted by varying the phase change between the two signals. PCT / GB / 2004002016 also refers to the introduction of a variable relative phase change between two signals, which are then divided into components: vector combinations of the components are formed in order to provide respective driving signals for individual elements of antenna. Here again an electrical tilt is adjusted by varying the phase change between the two signals. There is, however, a problem in relation to the division of RF signals, to the extent that divisor ratios can be excessively high to be implemented in a single division operation: it may require two or more pegged operations, which causes increase in the size of the circuit, an increase in its cost and its complexity. The reason for this situation is the fact that the dividers are implemented by dividing a microtira track into a narrower strip circuit board with different impedance compared to the track before splitting. The microtire impedance is related to the track width through a highly complicated and empirical expression, but in the case of a typical board substrate thickness a 50 ohm track would be 2.8 mm wide. The track narrows as the impedance rises until it is too narrow for a reliable bond with the substrate. The inability to produce a reliable bond occurs at runway widths less than about 0.2 mm; this width provides an impedance of approximately 150 Ohms which represents a ratio of divisors of 9.5 dB, therefore it is not desirable to exceed this value in the case of a single divider. PCT / GB2004 / 001297 requires divisor ratios of 19 dB, which means cascading at least two divisor operations. Other potential problems are the following: a) an excessive number of divisor outputs may be required for implementation in a single divisor; b) the fact of widely varying the divisor ratios reduces the range of frequencies over which an antenna can tilt while retaining a desirably low side-lobe level; and c) several splitters result in a corporate signal feed network to an antenna with different feeder lengths to the individual antenna elements. Among these problems, c) requires the insertion of additional components in such a way that the transit time of signals to each element is the same to obtain a neutral network in phase and an optimized frequency response. All these problems make desirable the reduction of the number of divisors and the proportions between divisors. It is an object of the present invention to provide an alternative form of phase array antenna system with controllable electrical tilt, which includes an antenna with multiple antenna elements, characterized in that the system has: a) a device for providing two base signals with variable relative delay between them, b) division device for dividing the base signals into components of signals, c) a phase-to-power conversion device for converting the signal components into transformed components having powers that vary as the relative delay varies, and d) a power-to-phase conversion means for converting the transformed components into signal signals. pulse of antenna element having phases varying from antenna element to antenna element progressively through the antenna when the antenna is electrically inclined and which vary individually as the relative delay varies. The invention offers the advantage in the sense that it allows to control the electric inclination with a single variable relative delay, although several delays can be used if it is required in order to increase the obtainable electric tilt range, and requires relatively few division operations. . The phase-to-power conversion device may be several hybrid radiofrequency coupling devices ("hybrids") arranged to provide sums and. differences of pairs of signal components, each pair having signal components of both base signals. There may be a plurality of 180 ° hybrids arranged in order to provide sums and differences of pairs of signal components, each pair having signal components of both base signals. Each pair can have signal components of equal magnitude, with the component magnitude of each pair not being equal to that of another pair. The hybrids may be first hybrids and the power-to-phase conversion device may incorporate several second hybrid arrangements arranged to generate the antenna element pulse signals. The dividing device can be a first division device and the power-to-phase conversion device can incorporate a second division device arranged to divide the sums and differentiate into components for entry into the second hybrids. The first division means may be arranged to divide each of the base signals into three signal components. The second dividing device can be a plurality of two-way dividers. In a preferred embodiment, the invention is arranged in such a way that all paths for base signals to antenna elements contain the same numbers and types of components. In another aspect, the present invention offers a method for controlling the electrical tilt of a phase array antennas system that includes an antenna with multiple antenna elements, characterized in that the method incorporates the steps of: a) providing two signals of base with variable relative delay between them, b) dividing the base signals into signal components, c) converting the signal components into transformed components that have powers that vary as the relative delay varies, and d) converting the transformed components into signals of pulse of antenna elements having phases that vary from antenna element to antenna element progressively through the antenna when the antenna is electrically inclined and that vary individually as the relative delay varies. The method aspect of the present invention may incorporate preferred features mutatis mutandis equivalent to the features of the antenna system aspect. In order that the invention may be more fully understood, modalities thereof will be described below, by way of example only, with reference to the accompanying drawings in which: Figure 1 shows a vertical radiation pattern (VRP) of antenna phase sets with zero angles and non-zero electric tilt; Figure 2 illustrates a prior art phase set antenna having an adjustable electrical tilt angle; Figure 3 is a block diagram of a system of phase array antennas of the invention using a single time delay; Figure 4 is a block diagram of a set of phase array antennas of the present invention using two time delays; Figure 5 shows a power distribution network for use in the system of Figure 3 or 4; Figures 6a and 6b show an electrical power distribution network for use in a system of the invention having a 12-element antenna; Figure 7 is a schematic diagram of a 180-degree hybrid RF coupling device used in the networks of Figure 4 and Figure 6; Figures 8a and 8b are vector diagrams illustrating phases of pulse signals of antenna elements produced by the network of Figure 6; Figure 9 shows a 180 degree hybrid 182 receiving inputs A and B of two voltages Va and Vb of equal amplitude having a relative phase shift of f between them; Figure 10 is a vector diagram of the vectors + A, + B, -B, A + B, and A-B; Figure 11 shows how relative magnitudes of A + B and A-B (chain line) vary as their relative phase difference f is adjusted from minus 180 degrees to 0 to +180 degrees; and Figure 12 shows the phase variation of A + B and A-B as f is set from -180 degrees to 0 to +180 degrees. With reference to Figure 1, vertical radiation patterns (VRP) 10a and 10b of an antenna 12 which is a set of phases of individual antenna elements (not shown) are shown. The antenna 12 is flat, has a center 14 and extends perpendicularly to the plane of the drawing. The VRPs 10a and 10b respectively correspond to zero and non-zero variation in phase delay of antenna element signals with distance of assembly elements through the antenna 12 from an assembly edge. They have respective main lobes 16a, 16b with center lines or "physical axes" 18a, 18b, first upper lateral lobes 20a, 20b and first lower lateral lobes 22a, 22b; 18c indicates the physical axis direction for zero variation in delay for comparison with the non-zero equivalent 18b. By referring without the suffix "a" or "b", for example lateral lobe 20, it is referring to any of the relevant pair of elements, without distinction. The VRP 10b is inclined (downwardly as illustrated) relative to the VRP 10a, that is, there is an angle - the angle of inclination - between lines of main beam centers 18b and 18c having a magnitude that depends on the speed with the which varies the delay with the distance through the antenna 12. The VRP must meet several criteria: a) a high gain of physical axis; b) the first upper lateral lobe 20 must be at a sufficiently low level to avoid causing interference with moving radios using another cell; c) the first lower side lobe 22 must be at a level high enough for communications to be possible in the immediate vicinity of the antenna 12; and d) the level and direction of the side lobes must remain within predetermined design limits when the antenna is electrically inclined. These requirements are mutually in conflict, for example, the maximization of the physical axis gain can increase the lateral lobes 20, 22. In relation to a level of physical axis (length of main beam 16), it has been found that a maximum level of first-side lobe of m-18dB offers a convenient compromise in the overall performance of the system. The physical axis gain decreases in proportion to the cosine of the angle of inclination due to the reduction of the effective antenna aperture. Additional reductions in physical axis gain may result depending on how the angle of inclination changes.

The effect of adjusting either the mechanical inclination angle or the electric tilt angle is the repositioning of the physical axis in such a way that it points either up or down the horizontal plane, and consequently adjust the coverage area of the antenna. For maximum flexibility of use, a cellular radio base station preferably has both a mechanical tilt and an electrical tilt since each > of them has a different effect on the ground coverage, and also on other antennas in the immediate vicinity. It is also convenient that an electrical antenna tilt can be adjusted remotely from the antenna. In addition, if a single antenna is shared among several operators, it is preferable to offer a different angle of electrical tilt for each operator, even when this affects the antenna performance of the prior art. Referring now to Figure 2, a prior art phased array antenna system 30 is shown in which the electrical tilt angle is adjustable. The system 30 incorporates an input 32 for an RF radiofrequency transmitter carrier signal, the input is connected to an electrical power distribution network 34. The network 34 is connected through phase changers Phi.EO, Phi.ElL to Phi.E [n] L and Phi.Elü to Phi.E [n] U to respective radiation antenna elements EO, ElL to E [n] L and E1U to E [n] U of the system of phase set antennas 30: here a suffix U indicates upper and a suffix L indicates lower, n is an arbitrary positive integer that defines a size of sets of phases, and lines of points such as 36 that indicate the relevant element they can be replicated or removed as required for any desired overall size. The antenna system of phase assemblies 30 operates in the following manner. An RF transmitter carrier signal is fed to the electric power distribution network 34 through the input 32: the network 34 divides the signal (not necessarily equally) between the phase changers Phi.EO, Phi.ElL to Phi.E [n] L and Phi.Elü to Phi.E [n] ü, which change the phase of their respective divided signals and transfer them with phase change to associated antenna elements EO, ElL to E [n] L, E1U to E [n] U respectively. Phase changes are selected to choose an appropriate electric tilt angle. The power distribution between the EO antenna elements, etc. when the tilt angle is zero is selected to adjust the lateral lobe level and the physical axis gain appropriately. An optimal control of the electric tilt angle is obtained when the phase front through the set of EO elements, etc. is controlled for all inclination angles such that the level of the lateral lobe does not increase significantly in the tilt range . The electric tilt angle can be adjusted remotely, if required, by using a servomechanism to control the phase shifters Phi.EO, Phi.ElL to Phi.E [n] L and Phi.ElU to Phi.E [n] U, which can be mechanically operated. The antenna system 30 of phase sets has several disadvantages, such as: a) a phase changer is required for each antenna element, or "less profitably" by groups of elements; b) the cost of the antenna is high due to the number of phase changers required; c) cost reduction by applying phase changers to respective groups of elements instead of application to individual antenna elements increases the level of lateral lobe; d) a mechanical coupling of phase shifter to set delays correctly is difficult and mechanical links and gears are used which result in a non-optimal delay scheme; e) the level of the upper lateral lobe rises when the antenna is tilted downward causing a potential source of interference with mobile radios using other base stations; f) if an antenna is shared by different operators, all must use the same angle of electrical inclination; g) in a system with uplink and downlink at different frequencies (frequency division duplex system), the electric tilt angle in transmission is different from the electric tilt angle in reception. Referring now to Figure 3, a system of phase array antennas 40 of the invention having an adjustable electric tilt angle is shown. The system 40 has an input 42 for a transmitter carrier signal RF: the signal 42 is connected to a power splitter 44 which provides two output signals Via, Vlb which are signals input to a variable phase shifter 46 and a fixed phase shifter 48, respectively. Phase changers 46 and 48 can also be considered as time delays, since a phase change and a time delay are equivalent in a single frequency. They provide respective output signals V2a and V2b to an electric power distribution network 50, which will be described in more detail below. The network 50 offers four pulse signals that pass through fixed phase changers 58U1, 58U2, 58L1 and 58L2 to four equally spaced antenna elements 60U1, 60U2, 60L1 and 60L2 (U = upper, L = lower) respectively of a antenna of phase sets 60. Antenna 60 has a center indicated by a dotted line 61. The antenna could have any number of elements insofar as it has at least two elements. The array of phase sets antennas 40 operates in the following manner. An RF transmitter carrier signal is fed (single feeder) through the input 43 to the power splitter 44 where it is divided into Via and Vlb signals of equal power. The Via and Vlb signals are fed to the variable phase changer 46 and fixed phase changer 48, respectively. The variable phase changer 46 is controlled by an operator to apply a selectable phase change or a selected time delay, and the degree of phase change that is applied here controls the electrical tilt angle of the phase set antenna. The fixed phase changer 48 (which is convenient but not essential) applies a fixed phase change which, for convenience, is arranged to be half the maximum phase change fM applicable by the variable phase changer 46. This allows that Via is variable in phase in the range -fja / 2 to + fM / 2 in relation to Vlb, and these signals after the phase change become V2a and V2b as has been said after the output of the phase changers 46 and 48.

From the input signals V2a and V2b, the network 50 forms various vector combinations to provide a respective pulse signal for each antenna element 60U1, and so on. The pulse signals vary in phase linearly (or perhaps with a variable contour phase) as a function of the distance of antenna elements through the antenna 60 from an antenna element 60U2 or 60L2 at an edge, as required for producing a parallel beam from the antenna 60 inclined at an angle with respect to the physical axis of the whole. As is known in the technique of phase sets, the angle depends on the rate of phase change with the distance through the antenna 60. It can be seen (as will be described below) that the electric tilt angle of the set 60 simply varies by using a variable phase shifter, the variable phase shifter 46. This can be compared to the prior art requirement of Figure 2 to have several variable phase shifters, a respective phase shifter for each element of antenna. When the phase difference introduced by the variable phase changer 46 is positive, the electric tilt is made in the direction, and when the phase difference is negative, the electric inclination is made in the opposite direction. The fixed phase changers 58U1 et cetera, impose fixed phase changes that, between different antenna elements 60U1, etc. vary linearly (ignoring the phase variation) according to a geometric position of the element through the set 60: it adjusts to a direction of zero reference (18a or 18b in Figure 1) for the physical axis of set 60 when the phase difference between the Via and Vlb signals imposed by the variable phase changer 46 is zero. The fixed phase changers 58U1 etcetera are not essential but are preferred since they can be used to a) correctly provide the phase change introduced by the tilt process, b) optimize the suppression of side lobes in the tilt range, and c) introduce an optional fixed angle of electric tilt. If there are numerous users, each user may have a system of antennas of respective phase sets 40. Alternatively, if users are required to use a common antenna 60, then each user has a respective set of elements 42 to 50 in Figure 3, and a combination network is required to combine signals to feed them to the array of antennas 60. International Published Patent Publication Number WO 02/082581 describes such a network. Referring now to Figure 4, this drawing shows an additional set of phase array antennas 70 of the present invention utilizing two time delays or phase changes. The system 70 has an RF carrier signal input 72 connected to a first power divider 74, which provides two output signals Via, Vlb, for input to a first variable phase changer 76 and a first fixed phase changer 78 respectively. They provide the respective output signals V2a and V2b to a second fixed phase changer 80 and a second power changer 82. The first and second fixed phase changers 78 and 80 can be combined into a single unit if required. The second power divider 82 divides the signal V2b into two signals V3bl and V3b2 which are passed to a second variable phase changer 184 and a third fixed phase changer 86. The signals V3bl and V3b2 then pass to a first and second frequency networks. electric power distribution 88 and 90, respectively, which will be described in more detail below. The signal V2a passes through the second fixed phase changer 8b to a third power divider 92 for division into two signals V3al and V3a2 fed to the first and second electric power distribution networks 88 and 90, respectively. Networks 88 and 90 collectively provide 8 pulse signals that pass through fixed phase changers 94U1 to 94L4 to eight equally spaced antenna elements 96U1 to 96L4, respectively of a phase array antenna 96. Network 90 drives all four more internal antenna elements 96U1, 96U2 96L1 and 96L2 and network 88 drives the rest.

The array of phase array antennas 70 operates in the following manner. An RF transmitter carrier signal is fed (single feeder) through the input 72 to the first power divider 74 where it is divided into Via and Vlb signals of equal potential. The Via and Vlb signals are fed to the first variable and fixed phase changers 76 and 78, respectively. The fixed phase changer 78 applies a phase change of the half of the maximum phase change applicable by the variable phase changer 76. The first variable phase changer 76 provides part of the control of the electrical tilt angle of the antenna arrangement of 96, the second variable phase changer 76 provides the remainder of this control. The power distribution networks 88 and 90 receive input signals V3al / V3bl and V3a2 / V3b2, respectively, and form vector combinations of these signals to provide a respective pulse signal for each antenna element 96U1, etc. The pulse signals vary in phase linearly as a function of the antenna element distance through the antenna 96. The use of two variable phase changers 76 and 84 allows a greater phase change range to be applied through the antenna 96 that a single variable phase changer (as shown in Figure 3), and therefore a wider range of electrical tilt can be obtained. Referring now to Figure 5, an electrical power distribution network 100 is shown which is generally of the type used in 50, 88 and 90 in Figures 3 and 4, even though it is shown with more antenna elements associated with described equivalents above. The network 100 has two inputs 102a and 102b connected to the first and second three-way power dividers 106a and 106b, respectively. The first three-way power divider 106a divides an input signal or vector A with amplitude Va into three signals a.A, a2.A and a3.A, where a, a2 and a3 are proportions of scalar amplitude division. The al.A, a2.A, and a3.A signals are fed to the first inputs 1 of the first, second and third hybrid RF signal coupling devices 180 (hybrids) 110, 112 and 114, respectively. The second three-way power divider 106b divides an input signal or vector B with amplitude Vb into three signals bl.B, b2.B and b3.B, where bl, b2 and b3 are proportions of division and scalar amplitude of the signal. second divider 106b. The three signals bl.B, b2.B and b3.B are fed second inputs 2 of the hybrids 110, 112 and 114, respectively. The amplitudes of vectors A and B are equal, that is, Va = Vb. Hybrids 110 to 114 are known - also as hybrids of sum and difference. Each of the hybrids 110, 112 and 114 has sum and difference outputs Sl / Dl, S2 / D2 and S3 / D3, respectively, where the sum of vectors A + B and difference AB of their input signals A are found. and B. As will be described later in greater detail, it is a property of such hybrids that their sum and difference outputs have a fixed phase difference of 90 degrees between them when the amplitudes of their input signals are equal. This is the case even if the phase difference between these input signals varies. The sum signals A + B are in phase between them, as are the difference signals A-B, and the sum signals are at 90 degrees relative to the difference signals. As the phase difference between the input signals varies, due to the operation of the variable phase changer 46, the sum and difference output signals vary in magnitude: for example, with phase input signals of equal magnitude, A + B = 2A and AB = 0; with input signals of equal magnitude in antiphase, A + B = 0 and A-B = 2A; with input signals of equal magnitude that differ in phase by 90 degrees, A + B and A-B are both equal to "^ + ^" ~. The hybrids 11 ', 112 and 114 therefore act as phase-to-power converters since they convert input signals with constant power but variable phase difference into output signals with variable power but constant phase difference. The sum signals A + B from the SI outputs, S2, and S3 of the hybrids 110, 112 and 114 are fed to inputs referenced correspondingly with SI, S2, and S3 of fourth, fifth and sixth hybrids 180 116, 118 and 120, respectively. Similarly, the difference signals A-B of the outputs Di, D2 and D3 of the hybrids 110, 112 and 114 are fed to corresponding reference inputs DI, D2 and D3 of the sixth, fifth and fourth hybrids 120, 118 and 116 respectively. The fourth, fifth and sixth hybrids 116 to 120 also have sum and difference outputs indicated in each case by Suma and Dif. Where the sum of vectors A + B and difference A-B of their input signals appear respectively. The sum signals A + B are fed through respective fixed phase changers 122U1 to 122U3 to respective antenna elements 124U1 to 124U3 at the upper limit of a six element array of phase arrays 124. Similarly, the signals of difference AB are fed through fixed phase shifters 122L1 to 122L3 to respective antenna elements 124L1 to 124L3 in a lower half of antenna 124. Strictly speaking, phase changers 122U1 to 12U3 and antenna array 124 do not form part of the network 100 since Figures 3 and 4 that incorporate the network already show equivalents of these. The fourth, fifth and sixth hybrids 116 to 120 convert power difference between their inputs into phase difference in their outputs, and consequently act as power converters to phase.

There is additional flexibility in adjusting the required phase and amplitude to each antenna element 124L1, etc. if additional dividers are inserted between the outputs of a first, second and third hybrid 110 to 114 and the inputs of fourth, fifth and sixth hybrids 116 to 120. To avoid the need to dissipate power other than the antenna elements, when an output of first, second and third hybrid 110, 112 or 114 is divided, then additional hybrids and additional antenna elements are added to use all the RF power as efficiently as possible. Antenna elements 124U1 etc. they are associated with fixed phase changers 121U1, etc. whose purpose is a) to establish the nominal average inclination of the antenna and b) to optimize the level of the lobes of the antenna 124 in its range of inclination. In Figure 5, hybrids 110 to 120 with equal weighting applied to their inputs are shown: that is, with input signals A and B, then the sum output is (A + B) and the difference output is ( AB). However, they can also be constructed with unequally weighted inputs A and B to provide a sum output (xA + yB), and a difference output (xA - yB). Here, "x" is a weighting applied to the input A and "y" is a weighting applied to the input B. To 'conserve power in an unequally weighted hybrid, the total power that enters its input must be equal to the total power output from its outputs, ignoring inevitable thermal losses in a practical implementation. Two advantages result from the use of an unequally weighted hybrid: a) additional flexibility is added to the design in the optimization of antenna element phase and amplitude distributions; b) the signal division can be distributed between two or more divisor components thus reducing the maximum division ratio required of any individual divisor and improving the response to the frequency. As used in the system 40, the advantages of the electric power distribution network 100 are the following: a) only one division operation is required in the dividers 106a and 106b, each of which divides into only three signals; b) an inclination is implemented with a single variable phase changer or single time delay device 46; c) the signals at the network inputs 102a and 102b and components in which they are converted pass exactly through the same number and types of components along paths to the antenna elements 124U1, etc., i.e., a divider and two hybrids (as said in strict terms the phase changers 122U1 etc. are not part of the network 100). These trajectories should therefore have substantially the same electrical length ignoring the variation caused by non-zero manufacturing tolerances. Consequently, phase and amplitude errors in the network due to different types of components in different trajectories are avoided and a good beam shape is conserved in the tilt range. In addition, the beam shape is conserved over a wide range of frequencies since the phase and amplitude errors of each path to an element also vary and reduce the error between adjacent antenna elements; c) the antenna can be implemented without the need to dissipate RF power in any component other than the antenna elements, ignoring characteristics of components that are ideal properties; d) the cost of a phase array antenna is reduced compared to a comparable performance antenna that uses several variable time delay devices; and e) the reliability of the antenna is not compromised by the use of a large number of variable time delay devices. Dividers can be inserted between outputs of the first three hybrids 110 to 114 and the inputs of the other hybrids 116 to 120 in order to introduce additional flexibility in establishing phase and amplitude of signals fed to antenna elements. This will be described in the following modality. With reference now to Figures 6a and 6b, an additional electrical power distribution network 140 is shown in two sections 140a and 140b: the network 140 is for use with a phase array antenna of twelve elements at equidistance 148 but in other aspects of the type used in 50, 88 and 90 in Figures 3 and 4. The network 140 is equivalent to the network described with reference to Figure 5 with an additional column of splitters 142c to 142h and sufficient hybrids 1444 to 144g and fixed phase shifters 146U1 to 144L6 to provide signals for an increased number of antenna elements 148U1 to 148L6 of antenna 148. Parts equivalent to the parts described above have the same reference numbers and the description will focus on the aspects that are different. As before, two input signal vectors A and B, having respective amplitudes Va and Vb, at the inputs 102a and 102b are divided into al.A, a2.A, a3.A and blB, b2B, b3B signal fractions. by dividers 106a and 106b and fed to the first and second inputs 1 and 2 of the first, second and third hybrids 110 to 114: that is, signals a [n] .A and b [n] .B are entered into the n-th hybrid 110 + 2n, n = 0, 1 and 2. The division proportions are set in such a way that at a level of al = bl, a2 = b2 and a3 = b3 in order to implement a phase to power conversion in the hybrids 110 to 114. Referring now also to Figure 7, this drawing shows schematically a 180-degree hybrid coupler 132 with inputs A and B and outputs A + B and AB. The curves 134 indicate trajectories from input to outputs, and associated marks -180 and -360 indicate phase change or equivalent delay experienced by signals passing along such trajectories. As shown, trajectories 134 from A input 1 and B input 2 to Sum A + B output and from A to difference output AB are all associated with phase changes -180 degrees, while path 135 from B input 2 to AB difference output is related to a phase change of -360 degrees. A phase shift of 180 degrees inverts a sinusoidal signal or multiplies that signal by -1, while a phase change of -360 degrees leaves it unchanged. Therefore, both the A signal and the B signal are inverted to the para to the Sum output and therefore are added to each other, but only the B signal is inverted in the Difference output and therefore subtracted from A. As will be further described Further, if two vectors of equal magnitude but different phase signals are added together or both are subtracted through a 180 degree hybrid, the resulting sum and difference vectors are 90 degrees apart regardless of the phase difference of entry. Accordingly, A + B and A-B differ in phase by 90 degrees, which is convenient (but not essential), since it simplifies the calculation of the antenna element signal phase as will be described later. The hybrids 110 to 114 therefore act as phase-to-power converters, converting input signals for example (alA / blB) with equal amplitude but variable phase difference relative in sum and difference output signals with variable power but with difference of constant phase of 90 degrees. In addition, the outputs A + B of all three hybrids 110 to 114 are in phase between them and are at 90 degrees relative to all three A-B outputs of these hybrids. The hybrids 110 to 114 have outputs A + B connected to two-way splitters 142c, 142e and 142g, respectively, and outputs A-B connected to two-way splitters 142d, 142f and 142h, respectively. The dividers 142c to 142h divide their input signals into signal fractions cl / c2, dl / d2, the / e2, fl / f2, gl / g2 and hl / h2, respectively: these fractions are also used as reference marks for respective divisor outputs, and are for entry to entries with corresponding reference number cl to h2 from four to nine hybrids 1444 to 1449. The fourth to ninth hybrids 1444 to 144g have inputs A and B 1 and 2 and sum outputs A + B and difference AB. Sum and Dif., and have the same construction and mode of operation as the first, second and third hybrids 110 to 114. Table 1 below shows that inputs from the fourth to the ninth hybrids 1444 to 1449 receive which signal fractions: here the +/- signs indicate addition / subtraction of vectors, respectively. Table 1 Hybrid Entry Fraction 1444 1 cl. (al.A + bl.B) 1444 2 di. (al. - bl.B) 1445 1 c2. (al. + bl.B) 1445 2 d2. (al. - bl.B) 1446 1 el. (a2.A + b2.B) 144s 2 fl. (a2.A - b2.B) Hybrid Input Fraction 1447 1 e2. (a2.A + b2.B) 1447 2 f2. (a2.A - b2.B) 1448 1 gl. (a3.A + b3.B) 1448 2 hl. (a3.A - b3.B) 1449 1 g2. (a3.A + b3.B) 1449 2 h2. (a3.A-b3.B) The splitters 142c to 142h divide their input signals into appropriate signal fractions for addition and subtraction to form antenna element pulse signals progressively with the antenna element position to • through antenna 148. Table 2 below shows which Sum / Diff outputs. from the fourth to the ninth hybrid 1444 to 1449 drive which antenna elements 148U1 to 148L6 through respective fixed phase changers 146U1 to 144L6. Antenna elements 148U1 to 148U6 in the upper half of antenna 148 are all driven from the Sum outputs of the fourth to the ninth hybrid 1444 to 144g, but the antenna elements in the lower half are driven from the outputs of difference Dif. of these hybrids. Each of the fourth to the ninth hybrid outputs 1444 to 144g receives signal contributions that originate in sum or difference outputs from the first to the third hybrid 110 to 114 but not from both types of output. Its input signals are therefore in phase between them. The fourth to ninth hybrids 1444 to 1449 therefore act as power converters to phase: each one converts its "two input signals (which have zero phase difference but not necessarily equal amplitude) into sum and difference output signals by difference of phase that varies between different hybrids but constant power (ignoring any provision for variation of amplitude) .The arrangement shown allows to achieve a progressive phase front through the antenna 148 and allows the effective utilization of all the input power. ignores the possibility of losses due to dissipation of power in non-ideal components Excluding such losses, the electric power distribution network 140 does not generate a signal that can not usefully contribute to antenna impulse signals, so that it does not it is necessary to inefficiently dispose of some input power, the fourth hybrid 1444 drives a more external pair of the antenna components 148U6 to 148L6. The fifth to the ninth hybrid 1445 to 1449 drive pairs of antenna elements 148U5 / 148L5, 148U4 / 148L4, 148U3 / 148L3, 148U2 / 148L5 and 148U1 / 148L1, respectively that are progressively closer to an antenna center 150 where it is centered each pair. Table 2 below shows output signals from hybrids 1444 to 1449. Divider fractions cl etc. they are not necessarily scalar quantities, but the terms in parentheses in Table 2 column 4, for example (al.A + bl.B) and (al. - bl.B), are additions and subtractions of vectors. Phase differences are imposed between Va and Vb in accordance with that described above with reference to Figure 3 or Figure 4 and vectors are indicated by bold characters. In addition, as previously described, resulting from vector additions (al.A + bl.B), etc. between signals of equal magnitude they are all in phase between them and differ in phase by 90 degrees with all vector subtractions (al.A - blB) etc. These subtractions of vectors are therefore automatically square with vector additions.

Table 2 Hybrid Element Sali Antenna 148U6 1444 Sum cl. (al.A + bl.B) + dl (al.A-bl.B) 148U5 1445 Sum c2. (al.A + bl.B) + d2, (al.A-bl.B) 148U4 1446 Sum the. (a2.A + b2.B) + fl. (a2.A-b2.B) 148U3 1447 Sum e2. (a2.A + b2.B) + f2. (a2.A-b2.B) 148U2 1448 Sum gl. (a3.A + b3.B) + hl. (a3.A-B3.B) 148U1 1449 Sum g2. (a2.A + b3.B) + h2. (a3.A-B3.B) 148L1 1449 Dif. g2. (a3.A + b3.B) -h2. (a3.A-B3.B) 148L2 1448 Dif. gl (a3.A + b3.B) -hl. (a3.A-B3.B) 148L3 1447 Dif. E2. (a2.A + b2.B) -f2 (a2.A-b2.B) 148L4 144e Dif. El. (a2.A + b2.B) -fl (a2.A-b2.B) 148L5 1445 Dif. C2. (al.A + bl.B) -d2. (al.A-bl.B) 148L6 1444 Dif. Cl. (al.A + bl.B) -di. (al.A-bl.B) The expressions in the fourth column of Table 2 have the form P + Q, where Q is a vector in quadrature with a vector P. All vectors P are in phase between them and all the vectors Q are in phase between them. Therefore they can be written as P + jQ, where P and Q are of scalar magnitudes of P and Q. For example, in the case of the antenna element 148U6: P = cl. (al.A + bl.B) and Q = d2. (al.A - bl.B) (1) Where Pn and Qn for the in-phase and quadrature components of the voltage supplied to the n-th upper antenna element and the n-th lower antenna element 148Un and 148Ln, respectively (n = 1 to 6), phase 0n This voltage is provided by: where Qn is positive for the antenna element 148A in the upper half of the antenna 148 and negative for the antenna element 1 8Ln in the lower half. The scalar magnitude Vn of the voltage of the n-th antenna element is provided by: v. - $ + < &) (3) Proportions of dividers in this mode of network 140 are shown through Table 3 below. Table 3 Divisor Output of Division Divisor Voltage Divisor at 0.2500 -9.5db 102a a2 0.5000 -7.20dB a3 1.0000 -1.18dB bl 0.2500 -9.5dB 102b b2 0.5000 -7.20dB b3 1.0000 -l.lßdB cl 1.0000 -3.00dB 142c c2 1.0000 -3.00dB di 1.0000 -0.97dB 142d d2 0.5000 -7.00dB the 1.0000 -3.00dB 142e e2 1.0000 -3.00dB fl • 1.0000 -0.97dB 142f f2 0.5000 -7.00dB gl 1.0000 -3.00dB 142g g2 1.0000 -3.00dB hl 1.0000 -0.97dB 142h h2 0.5000 -7.00dB All contributions, (eg cl. (Al.A + bl.B) to signals reaching antenna elements 148U1 to 148L6 from inputs 102a and 102b pass through the same numbers and component types: that is, each contribution passes through a path that contains a three-way divider, a hybrid, a two-way splitter, a hybrid, and a fixed phase shifter. phase, that is, additional components to correct for different phase changes in different trajectories The use of two divisors in each path allows for moderate division proportions: this is useful because, as previously described, it is desirable that a splitter ratio do not exceed 9.5 dB The three-way divisors 106a and 106b primarily establish amplitude variation and the two-way divisors 142c to 142h primarily establish phase variation: here, "variation" is refers to amplitude or phase profile through antenna elements 148U1 to 148L6. The design of the network 140 is symmetric with repeated blocks of functions and lends itself to a relatively easy optimization. It is also easily adapted to different numbers of antenna elements in antennas by changing the number of dividers and hybrids. It has relatively few divisors in relation to the number of antenna elements in array 140. Figure 8a is a vector diagram of pulse signals produced by network 140 for antenna elements 148U1 to 148U6 in the upper half of antenna 148 : the effects of phase changers 146U1 to 146L6 have been ignored for convenience. Horizontal arrows, vertical and inclined such as 160, 162 and 164 indicate in-phase components, quadrature components and signal vectors of real antenna elements, respectively. Circulated numbers 1 to 6 such as 166 indicate adjacent signal vectors associated with antenna elements 148U1 to 148U6 respectively. Equivalent vectors (not shown) for pulse signals for antenna elements 148L1 to 148L6 in the lower half of the antenna 148 can be obtained by causing each vertical arrow 162 to extend downward from horizontal axes 168 instead of extending upwards ( that is, producing mirror images respecting signal vectors 164 by reflection on horizontal axes 168. Figure 8a shows that network 140 produces antenna element pulse signals with correctly progressive phase through antenna 148. A Optimal performance of the antenna 148 is obtained when a maximum tilt angle is selected that corresponds to the maximum available side lobe level when tilted in. The splitter ratios are then chosen to provide a linear phase front for this maximum tilt angle. Figure 8b is a complete vector diagram corresponding to Figure 8a but showing vector s of the antenna element pulse signal indicated by solid arrows such as 169 for the entire antenna array 140. Referring now to FIGS. 9 to 12, FIG. 9 shows an array 180 of a single 180-degree hybrid 182 that receives inputs A and B of two voltages Va and Vb of equal amplitude that have a relative phase change of f between them. These voltages are obtained by taking a single voltage V to an input 184, dividing it into two equal voltages at 186 and passing one of the resulting voltages through a variable phase changer 188. Hybrid 182 generates sum and difference output signals A + B and AB from input signals A and B. Figure 10 is a vector diagram of the vectors + A, + B, -B, A + B and AB, the last two being chain lines. Since A and B are equal, + A, + B and -B can be shown as radii of a circle 200 which is the circumscribed circle of the vector triangle + A, + B and A + B. Being equal and opposite, the vectors + B and -B collectively offer a diameter of the circle 200 and, by geometry, a diameter subtends a right angle at other points in the circle such as the origin 0. However, the vectors A + B and AB join the origin O at respective ends of the diameter + B / -B, such that the vectors A + B and AB have a right angle between them (or a relative phase shift of 90 °) regardless of the value of the phase difference f between + A and + B. Figure 11 shows how the relative magnitudes of A + B and AB (chain line) vary as their relative phase difference f is adjusted from -180 degrees to 0 to +180 degrees: A + B sinusoidally passes from 0 to 1 to 0 and AB passes cosinusoidally from 1 to 0 to 1. Figure 12 shows how the phases of A + B and AB (chain line) vary as f is set from -180 degrees to 0 to +180 degrees: A + B passes from -0 degrees to +90 degrees, and AB initially passes from 0 af = -180 degrees to +90 degrees af = 0, and then abruptly changes to -90 degrees when passing through 0, and then varies smoothly to 0 af = +180 degrees. The invention offers the control of electric tilt in the following manner. As said, the pulse signal to each antenna element 148U1, etc., in Figure 6 is a vector that can be written as P + jQ,. When the phase difference between the input vectors A and B (or voltages Va and Vb) is zero, ie f = 0, the difference output AB of all hybrids 110, etc., is also zero, as shown in Figure 11. Thus, when the antenna is not inclined, the impulse signals to all the antenna elements 148U1 etc., have the same phase, the phase "not inclined", and Q = 0 in P + jQ. When the phase difference between vectors A and B rises, Figure 11 shows that the difference outputs from the hybrids are raised while the sum outputs decrease. The value of Q rises accordingly while the value of P decreases. Thus, the phase angles of the pulse signals to each antenna element 148U1, etc., change. A progressively increasing phase front through the antenna elements is achieved by having progressively smaller values for P for antenna elements (for example 148U1 / 148L1) progressively closer to the center line 150 and progressively higher values for P for elements of antenna (e.g. 148U6 / 148L6) progressively farther from center line 150. A proportion of antenna driving power is consequently transferred from the center of antenna 148 towards its ends. This is achieved by an opriate connection of the outputs of the hybrids 110 to 114. Thus, in Figure 5, the central hybrid 112 of the first, second and third hybrids feeds the antenna elements 124U2 and 124L2 which are in the middle of the path between the antenna center shown as a dotted line and end elements 124U3 / 124L3 of the antenna 124 while the other two left-most hybrids 110 and 114 each have outputs of difference AB "exchanged", i.e. connected to a fourth or sixth hybrid 116 or 120 that receives the output A + B of the other hybrid (114 or 110). This arrangement changes the power in phase (vector component P) from the center towards the ends of the antenna 124 achieving a progressive phase front. Figure 11 shows that the phase of hybrid difference outputs changes by 180 degrees depending on whether the phase difference between vectors A and B is positive or negative. This ensures that there is a progressive phase front through the antenna that the antenna is tilted up or down. The embodiments of the invention described utilize 180 degree hybrids. They can be replaced, for example, by 90-degree hybrids "in quadrature" with the addition of 90-degree phase changers to globally obtain the same function, but it is less practical. The examples of the present invention described with reference to Figures 3 to 12 were discussed in terms of transmission operation. However, all the components are reversible and these examples can also operate as receivers. Hybrid and phase shifters are reversible and reverse dividers become recombiners as required in reception.

Claims (18)

1. CLAIMS 1. A system of phase array antennas with controllable electrical tilt that includes an antenna (124) with multiple antenna elements (124U1 to 124L3), characterized in that the system (40) has: (a) medium (46) ) to provide two base signals with variable relative delay between them, (b) dividing means (106a, 106b), to divide the base signals into signal components, (c) phase-to-power conversion means (110 to 114) for converting the signal components into transformed components having powers that vary as the relative delay varies, and (d) power-to-phase conversion means (116 to 120) for converting the transformed components into driving signals of antenna elements having phases that vary from an antenna element (for example 124U1) to an antenna element (for example 124U2) progressively through the antenna (124) when the antenna (124) is electrically inclined and that they vary individually as the relative delay varies. A system according to claim 1, characterized in that the means for converting phase to power consists of several hybrid ("hybrid") radio frequency coupling devices (110 to 114) placed to provide sums and pair differences of signal components, each pair having signal components from both base signals. 3. A system according to claim 1, characterized in that the means for converting phase to power consists of a plurality of 180-degree hybrids (110 to 114) arranged to provide sums and differences of pairs of signal components, each pair having signal components of both base signals. A system according to claim 3, characterized in that each pair has signal components of equal magnitude, but the component magnitude of each pair is not equal to the component magnitude of another pair. 5. A system according to claim 3, characterized in that the hybrids are first hybrids (110 to 114) and the power-to-phase conversion medium incorporates several second hybrids (116 to 120) arranged to generate drive signals of antenna elements. 6. A system according to claim 5, characterized in that the dividing means is a first dividing means (106a, 106b), and the power-to-phase conversion means (116 to 120) incorporates a second means of division (142c to 142h) arranged to divide the sums and differences into components for entry to the second hybrids (1444 to 1449). 7. A system according to claim 6, characterized in that the first dividing means (106a, 106b) is arranged to divide each of the base signals into three signal components. 8. A system according to claim 6, characterized in that the second dividing means is a plurality of two-way dividers (142c to 142h). 9. A system according to claim 1, characterized in that it is arranged in such a way that all paths extending from the provision of base signal to antenna elements contain the same numbers and types of components. 10. A method for controlling the electrical tilt of a system of phase array antennas (40) including an antenna (124) with multiple antenna elements (124U1 to 124L3), said method is characterized in that it incorporates the steps of: ( a) providing two base signals with variable relative delay between them, (b) dividing the base signals into signal components, (c) converting the signal components into transformed components having powers that vary as the relative delay varies, and (d) converting the transformed components into drive signals of antenna elements having phases ranging from antenna element (eg 124U1) to antenna element (eg 124U2) progressively through the antenna (124) when the antenna ( 124) is electrically inclined and varies individually as the relative delay varies. 11. A method according to claim 10, which is characterized in that step c) is implemented using several hybrids (110 to 114) arranged to provide sums and differences of pairs of signal components, each having signal components of both base signals. 12. A method according to claim 10, characterized in that step c) is implemented using several 180-degree hybrids (110 to 114) arranged to provide sums and differences of pairs of signal components, each pair having components of signal of both base signals. 13. A method according to claim 12, characterized in that each pair has signal components of equal magnitude, but the component magnitude of each pair is not equal to the component magnitude of another pair. A method according to claim 12, characterized in that the hybrids are first hybrids and step d) is implemented using several second hybrids (116 to 120) arranged to generate the antenna element driving signals. A method according to claim 14, characterized in that the division into step b) is a first division and a second division is implemented in step d) to divide the sums and differences into components for entry into the second hybrids (116 to 120). 16. A method according to claim 15, characterized in that in the first division each of the base signals is divided into three signal components. 17. A method according to claim 15, characterized in that the second division is a plurality of two-way divisions. 18. A method according to claim 10, characterized in that all the paths that extend from the provision of base signal to antenna elements (124U1 to 124L3) contain the same numbers and types of components.