CN1792005A - Phased array antenna system with adjustable electrical tilt - Google Patents

Abstract

A phased array antenna system with adjustable electrical tilt includes an array (62) of antenna elements 621, to 6210. It has a splitter (44) dividing a radio frequency (RF) carrier signal into two signals between which a phase shifter (46) introduces a variable phase shift. Further splitters (52) and (54) divide the relatively phase shifted signals into two sets of five signals. Four of each of the sets of five signals are vectorially combined in a network of 180 degree hybrid couplers 601, to 604. This provides vector sum and difference components which together with the fifth members of the sets are fed to respective fixed phase shifters (56, 58) and 641, to 6410. The phase shifters 641, to 6410 provide signals which are appropriately phased for use as phased array drive signals for respective antenna elements 621, to 6210. Adjustment of the single phase shift provided by the variable phase shifter (46) changes the angle of electrical tilt of the entire antenna array (62).

Description

Phased Array Antenna System with Adjustable Electric Tilt

technical field

The invention relates to a phased array antenna system with adjustable electric inclination. It is applicable to many areas of telecommunications, but has particular application in cellular mobile radio networks, generally known as mobile telephone networks. More specifically, but without limitation, the antenna system of the present invention may be used with second generation (2G) mobile telephone networks such as the GSM system, and with third generation ( 3G) mobile phone network.

Background technique

Operators of cellular mobile radio networks generally utilize their own base stations, each having at least one antenna. In a cellular mobile radio network, the antenna is the main factor defining the coverage area over which communication with the base station can take place. This coverage area is typically divided into many overlapping cells, each cell being associated with a respective antenna and base station. These units are also often divided into many sectors to increase communication coverage.

Each sector's antenna is connected to a base station for radio communication with all mobile radios within that sector. These base stations are interconnected by other means of communication, usually point-to-point radio links or fixed land lines, allowing mobile radio devices to communicate with each other through the coverage area of the cell, as well as with Public telephone network communications.

Cellular mobile radio networks using phased array antennas are known: such antennas comprise an array (usually 8 or more) of individual antenna elements, such as dipole or patch antennas. The antenna has a radiation pattern consisting of a main lobe and side lobes. The center of this main lobe is the direction of maximum sensitivity of the antenna, ie the direction of the antenna's main radiation beam. It is a well known property of phased array antennas that if the signal received by the antenna elements is delayed by a time that varies linearly with the distance from the edge of the array, then the main radiation beam of the antenna is steered in the direction of the increasing delay. The angle between the centers of the main radiation beam corresponding to zero and non-zero changes in the delay signal, ie the angle of steering, depends on the rate at which the delay varies with distance across the array.

The delay can be equivalently achieved by changing the phase of the signal and thus changing the phased array represented. It is therefore possible to vary the main radiation beam of the antenna pattern by adjusting the phase relationship between the signals fed to the different antenna elements. This causes the radiation beam to be steered to modify the coverage of the antenna.

It is necessary for operators of phased array antennas in cellular mobile radio networks to adjust the vertical radiation pattern of their antennas, ie the cross-section of the pattern in the vertical plane. This necessitates changing the vertical angle of the antenna's main radiation beam, known as the "tilt", to adjust the antenna's coverage. Such adjustments may be necessary, for example, to compensate for changes in the cellular network structure or in the number of base stations of the antennas. It is known that the adjustment of the antenna inclination can be both mechanical and electrical, and both individually and in combination.

The antenna tilt can be adjusted mechanically by moving the antenna elements or their housings (radomes): this is called "mechanical tilt" angle adjustment. As mentioned earlier, the antenna tilt can be adjusted electrically without physical movement by changing the time delay or phase of the signal sent to or received from each antenna array element (or group of elements): this is called "electrical tilt". ” Angle adjustment.

The vertical radiation pattern (VRP) of a phased array antenna has a number of notable requirements when used in a cellular mobile radio network:

1. High main lobe (or line of sight) gain;

2. A first upper sidelobe level low enough to avoid interference with mobile phones using base stations in different cells or networks;

3. A first lower sidelobe level high enough to allow communication in the immediate surrounding area of the antenna.

These requirements are in conflict: for example, an increase in boresight gain increases the level of side lobes. A first upper sidelobe level of -18dB relative to the boresight gain has been found to provide a convenient compromise in overall system performance.

The effect of mechanical tilt adjustment or electrical tilt adjustment is to reset the line of sight so that it points above or below the horizontal plane, thereby changing the coverage area of the antenna.

It would be desirable to be able to vary both the mechanical and electrical inclinations of the cellular radio base station antennas: this allows the greatest flexibility in the optimization of cell or sector coverage, since these inclinations The form has a different impact on the ground coverage of the antenna and on other antennas in the immediate surrounding area of the base station. Furthermore, operational efficiency can be improved if the electrical tilt can be adjusted remotely from the antenna assembly. However, the mechanical tilt of the antenna can be adjusted by resetting its radome, and the change of its electrical tilt requires additional electronic circuits, which will increase the cost and complexity of the antenna. Also, if a single antenna is shared among many operators, it is preferable to provide each operator with a separate electrical tilt.

The need for a separate electrical tilt from a shared antenna has not been met so far and has resulted in compromises in system performance. If the gain is reduced due to the technique used to change the electrical tilt, then the system performance will be further degraded.

R.C. Johnson, Antenna Engineers Handbook 3rd Edition 1993, McGraw Hill, ISBN 0-07-032381-X, Ch 20, Figure 20-2 discloses a phased array antenna for local or remote adjustment method of electrical inclination. In this method, a radio frequency (RF) transmitter's carrier signal is sent to an antenna and distributed to the antenna's radiating elements. Each antenna element has a variable phase shifter associated with it so that the signal phase can be adjusted as a function of distance across the antenna to vary the electrical tilt of the antenna. When there is no dip, the power distribution is proportional so that sidelobe levels and line-of-sight gains can be set. Optimal control of the dips is obtained when the phase fronts for all dips are controlled so that the sidelobe levels do not grow beyond the dip range. Electrical tilt can be adjusted remotely if desired by controlling the position of the phase shifter using a servo mechanism.

Antennas in prior art methods have a number of drawbacks. A variable phase shifter is necessary for each antenna element. The cost of the antenna is high due to the number of phase shifters required above. Although cost can be reduced by using a single common delay device or phase shifter for a set of antenna elements instead of each element, this increases sidelobe levels. See, for example, published International Patent Application No. WO03/036756A2 and Japanese Patent Application No. JP20011211025A.

While the mechanical coupling of delay devices can be used to adjust the delay, doing so properly is difficult; moreover, the mechanical connections and gears result in a non-optimal delay profile. When the antenna is tilted down, the upper side lobe level increases, thereby causing an interference voltage source to mobile phones using other base stations. If the antenna is shared by many operators, the operators hold a common electrical inclination instead of different inclinations which are more optimal. Finally, if the antenna is used in a communication system with uplink and downlink at different frequencies (frequency division duplex system), the electrical inclination in transmit mode is different from that in receive mode due to the frequency dependence in the characteristics of the signal processing components.

International Patent Application Nos. PCT/GB2002/004166 and PCT/GB2002/004930 describe the local or remote adjustment of the electrical tilt of an antenna by means of the difference between a pair of signal feeds connected to the antenna.

Contents of the invention

It is an object of the present invention to provide an alternative phased array antenna system.

The present invention provides a phased array antenna system having adjustable electrical inclination and comprising an array of antenna elements, characterized in that the system comprises:

a) a variable phase shifter for introducing a variable relative phase shift between the first and second RF signals,

b) splitting means for splitting relatively phase-shifted first and second signals into component signals, and

c) the signal combining network used to form the vectorial combination of the component signals to provide each individual antenna element with its own drive signal which is properly phased with respect to the other drive signals so that the electrical inclination of the array Adjustable in response to changes in the variable relative phase shift introduced by the variable phase shifter.

The present invention provides the advantage of making it possible to adjust the electrical tilt for the entire array using only a single variable phase shifter, instead of using one variable phase shifter per antenna element or group of antenna elements as in the prior art . An extended range of electrical tilt can be obtained if one or more additional phase shifters are used.

An antenna system may have an odd number of antenna elements. The variable phase shifter may be a first variable phase shifter, the system includes a second variable phase shifter arranged to phase shift the component signals that have been phase shifted by the first variable phase shifter, and the The second variable phase shifter provides an additional component signal output for the signal combining and phase shifting network either directly or through one or more splitter/variable phase shifter combinations.

The variable phase shifter may be one of a plurality of variable phase shifters, and the signal phase shifting and combining network is arranged to generate antenna element drive signals from component signals, some of which have passed through all variable phase shifters, and which Some don't.

The splitting means may be arranged to split the component signal into further component signals for input to the signal phase shifting and combining network. Signal Phase Shifting and Combining Network The component signals can be phase shifted and vector combined using phase shifters and 3dB directional couplers (combiners). The combiner may be a 180° combiner, also known as a sum and difference combiner. The combiners can be constructed as ring combiners, each of which has a circumference of (n+1/2)λ and input and output ports separated by λ/4, where n is an integer and λ is the the wavelength of the RF signal in the material of the device. The input and output ports of each synthesizer are impedance matched to the system.

A combiner for vector combining component signals may be designed to convert the input signals I1 and I2 into vector sums and vector differences other than (I1+I2) and (I1-I2).

Splitters, variable phase shifters, and signal phase shifting and combining networks can be co-located with the antenna array to form an antenna assembly with a single RF input power feed from a remote source. Alternatively, the splitting means may include first, second and third splitters, the first splitter is installed together with a variable phase shifter away from the second and third splitters, the second splitter and the third splitter, the signal phase shifting and combining network and the antenna array are co-located as an antenna arrangement, and the arrangement has dual RF input power feeds from a remote source, a first splitter and a first variable phase shifting The device is located at a remote source.

The variable phase shifter can be a first variable phase shifter connected in the transmit path, the system includes a second variable phase shifter connected in the receive path: there can be similar transmit and receive paths to provide a fixed phase instead of a variable phase shift: the signal shift is then arranged by generating the antenna element drive signal in response to the signal in the transmit channel, and generating the receive channel signal from the signal formed by the antenna elements operating in the receive mode. Phase and combination networks operate in both transmit and receive modes. Then, the electrical inclination is independently adjustable in each mode.

The variable phase shifter may be one of a plurality of variable phase shifters associated with a respective operator, and the system includes filtering and combining means for after phase shifting in each variable phase shifter The signal is routed to a common signal feed connected to a splitting device and a signal combining and phase shifting network to provide a signal to an antenna containing signals from two operators with independently adjustable electrical inclination Impact. The plurality of variable phase shifters may include a respective pair of variable phase shifters associated with each operator, and the system may have components with both forward and reverse signal processing capabilities, such that the system operates at Operates in both transmit and receive modes, with independently adjustable electrical tilt in each mode.

In another aspect, the present invention provides a method of adjusting the electrical tilt of a phased array antenna system comprising an array of antenna elements, characterized in that the method comprises:

a) introducing a variable relative phase shift between the first and second RF signals,

b) splitting the relatively phase-shifted first and second signals into component signals, and

c) Vector combining and relative phase shifting of the component signals to provide each individual antenna element with its own drive signal that is properly phased relative to the other drive signals so that the electrical tilt response of the array Adjustable for changes in the variable relative phase shift.

The array may have an odd number of antenna elements.

The method may include generating at least one component signal that has undergone a phase shift in a plurality of variable phase shifters. The variable phase shifters described above may be in groups, the method comprising generating antenna element drive signals from the component signals, some of which pass through all the variable phase shifters and some of which pass through none.

The method may include splitting a component signal into other component signals for input to a signal phase shifting and combining network. It can use phase shifters and combiners to phase shift and vector combine the component signals. These combiners may be 180° combiners. They may be ring combiners with a circumference of (n+1/2)λ and input and output ports separated by λ/4, where n is an integer and λ is the The wavelength of the RF signal. The branching means may also include the aforementioned ring combiners, one port of each combiner is terminated on a resistor equivalent to the system impedance to form a matching load.

A combiner for vector combining component signals may be designed to convert the input signals I1 and I2 into vector sums and vector differences other than (I1+I2) and (I1-I2).

The method may include supplying a single RF input signal from a remote source for signal separation, variable phase shifting and vector combining in a network co-located with the antenna array to form an antenna arrangement. Alternatively, the method may include feeding two RF input signals from remote sources to an antenna arrangement for signal separation, variable phase shifting and vector combining in a network co-located with the antenna array, where the two One of the RF input signals has a variable phase relative to the other. The method may use transmit and receive channels for operation in both transmit and receive modes, and generate an antenna element drive signal in response to a signal in the transmit channel, and an antenna element formed from an antenna element operating in receive mode. The receive channel signal is generated from the signal.

The variable phase shifter may be one of a plurality of variable phase shifters associated with a respective operator, and the method may comprise:

a) After phase shifting in the individual variable phase shifters, the signals are filtered and combined and delivered to a common signal feed which is connected to the splitting device and the signal combining and phase shifting network ;

b) provide signals to antennas containing influences from both operators; and

c) Independent adjustment of electrical tilt in relation to each operator.

The plurality of variable phase shifters may include a respective pair of variable phase shifters associated with each operator; the method may use components having both forward and reverse signal processing capabilities, and the method may include Operates in both transmit and receive modes, with independently adjustable electrical tilt in each mode.

Description of drawings

In order that the present invention may be more fully understood, embodiments thereof will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows the vertical radiation pattern (VRP) of a phased array antenna with zero and non-zero electrical tilt;

Figure 2 illustrates a prior art phased array antenna with adjustable electrical tilt;

Fig. 3 is a structural diagram of the phased array antenna of the present invention;

Figure 4 shows in more detail the signal combining network used in the system of Figure 3;

Figure 5 is a phase diagram of antenna element signals associated with a 90° phase shift introduced by a variable phase shifter in the system of Figure 3;

6 and FIG. 7 are partial structural diagrams of other phased array antenna systems of the present invention comprising 11 and 12 antenna elements (element spacing is not entirely in accordance with the scale in FIG. 6);

Figure 8 is a phase diagram of antenna element signals associated with a 90° phase shift introduced by a variable phase shifter in the system of Figure 7;

Fig. 9 is a partial structural diagram of another phased array antenna system of the present invention using two variable phase shifters;

Figure 10 is a partial block diagram of an antenna system of the present invention similar to that shown in Figure 9, but using groups of variable phase shifters;

Figures 11 and 12 illustrate the use of the invention with a single and two feed lines respectively;

Figure 13 shows a variant of the invention that allows the electrical tilt to be independently adjustable in transmit and receive modes;

14 is a block diagram of another phased array antenna system of the present invention illustrating an antenna shared by multiple users with two feed lines and a single tilt and transmit/receive capability;

FIG. 15 is a variation of the antenna system of FIG. 9 with variable phase shifters located away from each other; and

Figure 16 illustrates a phased array antenna system of the present invention including a circular 3 dB directional coupler.

Detailed ways

All illustrated embodiments use connections in which the signal source impedance is equal to the respective load impedance to form a "matched" system. A matched system maximizes power transfer from source to load and avoids signal reflections. Where the signal line is terminated with a resistor (see Figure 6, for example), the value of the resistor is equal to the system impedance to form a matched termination.

Referring to FIG. 1, vertical radiation patterns (VRPs) 10a and 10b are shown for antenna 12, which is a phased array of individual antenna elements (not shown). The antenna 12 is planar, has a center 14 and extends perpendicular to the plane of the figure. VRP 10a and VRP 10b correspond to zero and non-zero deviations, respectively, in the delay and phase of the antenna element signal having a distance across antenna 12. VRP 10a and VRP 10b have respective main lobes 16a, 16b with centerlines or "lines of sight" 18a, 18b, first upper side lobes 20a, 20b and first lower side lobes 22a, 22b; 18c is shown in delay Boresight direction for zero bias, for comparison with non-zero equivalent 18b. Designations without the suffix a or b, such as sidelobe 20, refer to either element of the pair without distinction. VRP 10b is tilted relative to VRP 10a (downward as shown in the figure), i.e. there is an angle-tilt angle between main lobe centerlines 18b and 18c, the magnitude of which depends on the delay across antenna 12 rate of change with distance.

The VRP must meet several criteria: a) high line-of-sight gain; b) the first upper sidelobe 20 should be at a low enough level to avoid causing interference to a mobile phone using another unit; and c) the first The lower side lobe 22 should be large enough to allow communication in the immediate surrounding area of the antenna.

These requirements are in conflict: for example, maximizing the line-of-sight gain increases the sidelobes 20,22. A first upper sidelobe level of -18dB relative to the boresight level (length of the main radiation beam 16) has been found to provide a convenient compromise in overall system performance. The boresight gain decreases proportionally to the cosine function of the inclination angle due to the decrease in the effective aperture of the antenna. The effect of further reductions in boresight gain will depend on the degree of inclination change.

The effect of adjusting the mechanical or electrical tilt is to reset the line of sight so that it points above or below the horizontal plane, thereby increasing or decreasing the coverage of the antenna. For maximum flexibility of use, cellular radio base stations preferably have both mechanical and electrical inclinations available, as each has a different effect on the shape and area of the ground coverage area and on the immediate surrounding area. Other antennas in the cell and in neighboring cells also have different effects. It would also be convenient if the electrical tilt of the antenna could be adjusted remotely from the antenna. Also, if a single antenna is shared among many operators, it is preferable to provide each operator with a single electrical tilt.

Referring now to FIG. 2, there is shown a prior art phased array antenna system 30 in which the electrical tilt is adjustable. The system 30 includes an input 32 for a radio frequency (RF) transmitter carrier signal connected to a power distribution network 34 . This network 34 is connected to the respective radiating antenna elements E0, E0, E1L to E[n]L and E1U to E[n]U: Here, the suffixes U and L represent the upper and lower parts, respectively, n is any positive integer greater than 2 that defines the size of the phased array, and a dashed line such as 36 ( denoting related elements) can be replicated as needed for any desired array size.

The phased array antenna system 30 operates as follows. The RF transmitter carrier signal is sent via input 32 to a power distribution network 34: this network 34 operates between phase shifters Phi.E0, Phi.E1L to Phi.E[n]L and Phi.E1U to Phi.E[n]U (not necessarily equal) between the latter phase-shift the signal they receive and pass the resulting phase-shifted signal to the respective associated antenna elements E0, E1L to E[n]L, E1U to E[n]U . The phase shift and signal amplitude to each element are selected for selecting an appropriate electrical tilt angle. When the tilt angle is zero, the power distribution of the network 34 is selected to properly set the sidelobe levels and the line-of-sight gain. Optimal control of dips is obtained when the phase front of all dips is controlled, so sidelobe levels do not grow significantly with dip range. If desired, the electrical tilt can be adjusted remotely by using servo-controlled phase shifters Phi.E0, Phi.E1L to Phi.E[n]L, and Phi.E1U to Phi.E[n]U, where the tilt activated mechanically.

The prior art phased array antenna system 30 has a number of deficiencies, as follows:

a) Each antenna element or each group of elements must have its own phase shifter;

b) high cost of the antenna due to the number of phase shifters required above;

c) cost reductions obtained by applying phase shifters to grouped elements increase sidelobe levels;

d) implementing mechanical coupling of phase shifters for correct setting of delays is difficult and uses mechanical linkages and mechanical gearing, which will lead to non-optimal delay configurations;

e) when the antenna is tilted downwards, the upper side lobe level increases, making it a potential source of interference to mobile phones using other units;

f) if different operators share an antenna, then all operators must use the same electrical inclination;

g) in systems where the uplink and downlink are at different frequencies (frequency division duplex systems), the electrical inclination in transmission differs from that in reception;

Referring now to FIG. 3, there is shown a phased array antenna system 40 of the present invention having adjustable electrical tilt. The system 40 comprises five consecutive functional regions 40 ₁ to 40 ₅ , referred to in the prior art as "stages" and shown between pairs of dashed lines, eg 41 . It has an input 42 for the RF carrier transmission signal: this input 42 is connected as an input to a power divider 44 which provides two output signals with amplitudes V1A, V1B, which become variable displacement Phaser 46 and the input of the first fixed phase shifter 48. Phase shifters 46 and 48 can be equivalently viewed as time delays. They provide respective output signals V2B and V2A to two power splitters 52 and 54 . Power dividers 52 and 54 have n outputs such as 52a and 54a respectively: where n is a positive integer equal to or greater than 2, and the dashed outputs 52b and 54b show that in each case the outputs can be according to any desired phase The control array size needs to be copied.

The outputs of power dividers such as 52a and 54a provide output signals having amplitudes Va1 to Va[n] and Vb1 to Vb[n] respectively (shown without letter V). As described in more detail below, some of these output signals will have equal amplitudes to other output signals, while others will not. In an embodiment with ten antenna elements (n=5) (to be described), Va1=Va2=Va3, Vb3=Vb4=Vb5; Va4=Vb2 and Va5=Vb1. These output signals are sent to a phase shifting and combining stage 40 ₄ comprising second and third fixed phase shifters 56 and 58 and a vector combining network generally indicated at 60 . Stage 40 ₄ will be described in more detail below: it provides drive signals to equally spaced antenna elements 62 ₁ to 62 _n of phased array 62 through respective fixed phase shifters 64 ₁ to 64 _n . As before, here n is any positive integer equal to or greater than 2, but it is equal to the value of n for power dividers 52 and 54, and the size of the phased array is 2n antenna elements. Internal antenna elements ₆₂₂ and ₆₂₃ are shown in dashed lines to show that they can be duplicated as required for any desired phased array size.

The phased array antenna system 40 operates as follows. The RF transmitter carrier signal is sent via input 42 to a (single feeder) power splitter 44 where it is split into signals V1A and V1B (equal power in this embodiment). Signals V1A and V1B are applied to variable and fixed phase shifters 46 and 48, respectively. Variable phase shifter 46 applies an operator-selectable phase shift or delay, and here the degree of phase shift applied controls the electrical tilt of antenna element ₆₂₁ and the entire phased array 62 of other antenna elements. The fixed phase shifter 48 is not necessary, but is a convenience: it applies a fixed phase shift, chosen for convenience to be half the maximum phase shift φ _M that can be applied by the variable phase shifter 46 . This makes V1A variable in phase relative to V1B in the range _-φM /2 to + _φM /2, and, after phase shifting, these signals become V2B and V2A, which, as already mentioned, are after the outputs of phasers 46 and 48.

Each of the power splitters 52 and 54 divides the signal V2B or V2A into respective sets of n output signals Vb1 to Vb[n] or Va1 to Va[n], wherein in each set of Vb1 and other signals or Va1 and The power of each of the other signals need not be equal to the power of the other signals in the group. The variation in signal power on groups Va1 and other signals and Vb1 and other signals is different for different numbers of antenna elements 62 ₁ and other antenna elements within array 62 .

One of the set of output signals Vb1 to Vb[n] is sent to the corresponding fixed antenna phase shifter 64 ₃ through the second phase shifter 56, and one of the set of output signals Va1 to Va[n] is likewise passed through The third phase shifter 58 is sent to another antenna phase shifter 64 ₈ . Second and third phase shifters 56 and 58 introduce filler phase shifts to compensate for the phase shift introduced by combining network 60 . The other signals in groups Vb1 to Vb[n] and Va1 to Va[n] are combined in pairs in network 60 to produce a vector summed resultant signal for driving _the respective Antenna element 62 ₁ etc. Fixed phase shifter ₆₄₁ and other fixed phase shifters impose a fixed phase shift that varies between different antenna elements ₆₂₁ and other antenna elements depending on the geometrical position of the elements on array 62: With zero phase difference imposed by variable phase shifter 46 between V1A and V1B, this sets the zero reference direction (18a or 18b in FIG. 1) for the line of sight of array 62. This antenna phase shifter ₆₄₁ and other antenna phase shifters are not required, but they are preferred because they can be used to a) correctly balance the phase shift introduced by tilt processing, and b) optimize over the range of tilt angles sidelobe suppression, and c) introducing an optional fixed electrical tilt.

By using a variable phase shifter, variable phase shifter 46, the electrical tilt of array 60 is also variable. This is compared to the prior art requirement of multiple variable phase shifters, only one for each antenna element or small group of antenna elements. When the phase difference introduced by the variable phase shifter 46 is positive relative to the fixed phase shift 48, the antenna is tilted in one direction, and when the phase difference is negative, the antenna is tilted in the opposite direction.

If there are multiple users, each user may have its own phased array antenna system 40 . Alternatively, each user can have a corresponding set of stages 40 ₁ and 40 ₂ in FIG. 3 if users are required to share a common antenna while retaining a single electrical tilt capability. Additionally, a combining network consisting of stages 40 ₃ , 40 ₄ and 40 ₅ must combine the signals from the resulting multi-group splitter 44 and phase shifters or delays 46 , 48 to feed it to the antenna array 62 . Published International Patent Application No. WO03/043127 A3 describes sharing in this way, but it uses an antenna with a plurality of small groups of antenna elements, each antenna element in a small group having the same phase of the element driving signal. In antenna system 40, antenna elements ₆₂₁ to _62n all have different element drive signal phases due to the need to improve phased array performance.

It can be seen that the antenna system 40 has good sidelobe suppression which can be maintained over the entire range of electrical tilt angles. The antenna system 40 can be implemented at a lower cost than current designs that provide similar levels of performance. Its electrical tilt can be adjusted remotely using a single variable delay device, and it allows different operators to share the device while giving each operator an individual electrical tilt. By modifying the antenna system 40 to include different paths and phase shifters for transmit and receive as will be described hereinafter, the electrical tilt can be either the same or different in the transmit mode than in the receive mode.

Referring now to FIG. 4, there is shown an embodiment 70 of the present invention for a phased array 62 of ten elements ₆₂₁ through ₆₂₁₀ . Wherein the same components as described above have the same reference numerals. FIG. 4 corresponds to portions 40 ₃ to 40 ₅ in FIG. 3 , and the positions of splitters 52 and 54 have been reversed as shown. Splitters 52 and 54 receive input signals V2B and V2A, respectively, of equal power but variable relative phase. Each of them splits its respective input into 5 signals, three of which are of the same magnitude (A or B), while the other two have magnitudes 0.32 and 0.73 times said magnitude (A or 0.32 or 0.73 of B).

Eight of the ten signals from splitters 52 and 54 pass through four vector combining devices 60 ₁ to 60 ₄ : each of these devices is a 180° combiner (marked H) with two There are two inputs, labeled I1 and I2, and two outputs, labeled S and D, for summing and difference, respectively. For convenience, the labels I1 and I2 are also used to indicate the signals at those ports. As those port names indicate, upon receiving input signals I1 and I2, each of the synthesizers ₆₀₁ to ₆₀₄ produces two output signals at S and D, which are their respective input Vector sum and vector difference of signals. Table 1 below shows the magnitudes of the input signals received by the synthesizers ₆₀₁ to ₆₀₄ , and the correspondingly generated output signals in vector form, represented in each case by arbitrary values A and B.

Table 1 synthesizer I1 input I2 input S output D output 60 ₁ A 0.73B 0.707(A+0.73B) 0.707(A-0.73B) 60 ₂ A 0.32B 0.707(A+0.32B) 0.707(A-0.32B) 60 ₃ B 0.32A 0.707(B+0.32A) 0.707(B-0.32A) 60 ₄ B 0.73A 0.707(B+0.73A) 0.707(B-0.73A)

Table 2 below shows the antenna elements which receive the output signals produced by the splitters 52, 54 and the combiners ₆₀₁ to ₆₀₄ via antenna phase shifters (PS) ₆₄₁ to ₆₄₁₀ .

Table 2 antenna element signal amplitude antenna element signal amplitude 62 ₁ 0.707(B-0.73A) 62 ₆ 0.707(A+0.73B) 62 ₂ 0.707(B-0.32A) 62 ₇ 0.707(A+0.32B) 62 ₃ B 62 ₈ A 62 ₄ 0.707(B+0.32A) 62 ₉ 0.707(A-0.32B) 62 ₅ 0.707(B+0.73A) 62 ₁₀ 0.707(A-0.73B)

One signal A or B from each splitter 52 or 54 is routed not through a combiner to an antenna phase shifter ₆₄₃ or ₆₄₈ , but through a phase shifter 56 or 58 which applies a phase shift φ which The shift is equal to and used to compensate for the phase shift imposed by one of the combiners ₆₀₁ to ₆₀₄ . This is called "padding". Each of the fixed phase shifter pairs _56/643 and _58/648 can be implemented as a single phase shifter. The input splitter 44 in FIG. 3 can (arbitrarily) provide an unequal power split, so the signal amplitudes V2A and V2B in FIG. 3 and FIG. 4 are different. In addition, combiners ₆₀₁ to ₆₀₄ (as described above) providing sum and difference vectors (I1+I2) and (I1-I2) may (optionally) incorporate all or part of the functionality of splitters 52 and 54 : That is, they can instead be designed to transform the inputs I1 and I2 into vector sums and differences other than I1+I2 and I1-I2, such as the sum of xI1+yI2, where x and y are unequal values. This is subject to the constraint that the overall output power plus combiner power dissipation must remain equal to the overall power input to combiners ₆₀₁ to ₆₀₄ . Also, instead of the 180° combiners 60 ₁ to 60 ₄ , combiners giving other phase shifts such as 60°, 90° or 120° can be used.

Referring now also to FIG. 5, there is shown a vector diagram of the antenna system 70 when the phase difference between signals V2A and V2B (having the same phase as A and B, respectively) is 90°, which in this embodiment is one The angle at which the phase front of an antenna element can be optimized. All vector sums and vector differences in Figure 5 (i.e. all vectors except A and B) should actually be multiplied by 2 ^-1/2 or 0.707 as shown in Tables 1 and 2, e.g. A+0.73B It should be 0.707(A+0.73B); but this multiplication constant is only a scaling factor and has been omitted from the figure to reduce complexity.

Antenna system 70 is optimized by determining the values of A and B in Tables 1 and 2 at a 90 degree phase difference at which antenna system 70 has a substantially linear phase wave across the antenna elements at two electrical inclinations front, and have equal phase fronts on the mean dip. Radiation arrows such as 80 terminated at ₈₂₁ to ₈₂₁₀ indicate the magnitude and phase angle of the phased array drive signal as they occur at antenna elements ₆₂₁ to ₆₂₁₀ , respectively. A slanted arrow such as 84 represents a radial offset from radial A or B (eg 0.73b or 0.32a). The two arrows 84a and 84b marking +0.73B and +0.73A are seen in this figure as enclosing the adjacent arrow 84 marking +0.32B and +0.32A and extending back therefrom to arrow Paths A and B.

For example, the double-headed arrow of 86 represents the phase difference between adjacent radial vectors, which is 22° between the signals on the outermost pair of antenna elements 62 ₁ /62 ₂ and 62 ₉ /62 ₁₀ , and which is in All other pairs of antenna elements 62 ₂ /62 ₃ to 62 ₈ /62 ₉ are 18° apart. The phase difference between 18° and 22° is small in the range of phased arrays: so for practical purposes, in adjacent pairs of antenna elements 62 _i /62 _i+1 (i=1 to 9) The phase difference between is substantially constant, and the phase change across array 62 is a substantially linear function of position in the array, as required for standard phased array operation.

As already mentioned above, Fig. 5 shows the case of a 90° phase difference between signals A and B or V2A and V2B. Zero phase difference corresponds to the average angle of tilt, and positive and negative phase differences correspond to positive and negative antenna tilt angles.

Referring now to FIG. 6, there is shown a portion of an antenna system 100 of the present invention comprising an odd number of antenna elements, in this example eleven antenna elements. System 100 is identical to embodiment 70 except for the addition of a few components, and the description below will focus on the differences. The same reference numerals are used for the same parts as those of the foregoing parts. System 100 differs from the previously described systems in that the difference outputs D of combiners 60 ₁ and 60 ₄ are not connected to phase shifters 64 ₁ and 64 ₁₀ but to two splitters 102 and 104 respectively . These splitters divide the signals from the combiners ₆₀₁ and ₆₀₄ into fractional parts c1/c2 and d1/d2 of respective amplitudes: in these parts c1 and d1 are sent to phase shifters ₆₄₁ and ₆₄₁₀ , to be used in driving antenna elements ₆₂₁ and ₆₂₁₀ . Fractional parts c2 and d2 are fed respectively to the I1 and _{I2 inputs of an additional fifth combiner 605, which is of the same type as combiners 601 and 604 .} The fifth synthesizer ₆₀₅ has a summing output S, which is terminated in a matched load 106, and a difference output D, which is passed through the φ-90° phase shifter 108 and the antenna phase shifter _64. connected to an additional centrally located antenna element 62 ₀ . In Figure 5, all antenna elements are equally spaced by the distance indicated by L, so the introduction of the central antenna element ₆₂₀ means that it is separated from the adjacent elements ₆₂₅ and ₆₂₆ (labeled in this figure as such, However, for the sake of convenience, the distance shown in the figure is larger than that in the actual situation) separated by L/2. However, the above-mentioned L/2 interval is not necessary.

The net effect of the improvements at antenna array 62 in FIG. 6 is that elements ₆₂₁ and ₆₂₁₀ have drive signals reduced to d1 (B-0.73A) and c1 (A-0.73B), and center element ₆₂₀ has Drive signal d2(B-0.73A)-c2(A-0.73B).

It can be seen that when tilted downward, the antenna system 100 has an asymmetrical vertical radiation pattern compared to tilted upward. As the antenna array 62 is electrically tilted up or down, there is an increase in signal power to the end antenna elements 62 ₁ and 62 ₁₀ . Ideally, sidelobe levels will be optimally controlled when the variation (amplitude taper) of the drive signal across the array remains substantially constant over the range of antenna tilt angles. In order to counteract the effect on the side lobes due to the consequent power increase at the end antenna elements ₆₂₁ and ₆₂₁₀ when tilting, a number of techniques can be used as follows:

1. An attenuator may be inserted in series with the end antenna elements ₆₂₁ and ₆₂₁₀ ;

2. Each of the end antenna elements ₆₂₁ and ₆₂₁₀ can be split into two, thereby adding two additional elements to the antenna;

3. More combiners may be used to divert power partially from the end antenna elements ₆₂₁ and ₆₂₁₀ to elements adjacent to the center of the antenna; and

4. Part of the power from the end antenna elements 62 ₁ and 62 ₁₀ can be used to drive the central element 62 ₀ , as indeed shown in FIG. 6 .

Antenna system 100 provides the following advantages:

1. When the antenna array 62 is electrically tilted, the side lobe level of the antenna is reduced.

2. When the antenna is tilted downward, the phase of the carrier or drive signal of the central element ₆₂₀ changes by 180° as the electrical tilt angle passes through an average value and further reduces the upper sidelobe level.

3. When the antenna is tilted down, the effect of reducing the upper sidelobe level is to reduce interference to mobile phones using a different channel than the one assigned to the antenna system 100 .

Referring now to FIG. 7 , a portion of an embodiment 120 of the present invention for a phased array 122 of twelve elements 122 ₁ to 122 ₁₂ is shown. The first and second splitters ₁₂₄₁ and ₁₂₄₂ respectively receive input signals represented in this example by vectors A and B: these vectors are of equal power, but have variable relative phases. The splitters ₁₂₄₁ and ₁₂₄₂ perform splitting respectively, splitting the respective input signals into three fractional parts a1/a2/a3 and b1/b2/b3: i.e., the signals a1A, a2A and a3A are output from the splitter ₁₂₄₁ , while the signal parts b1B, b2B and b3B are output from the splitter 124 ₂ . Signals a1A and b1B are sent to first and second φ stuffing phase shifters 128 ₁ and 128 ₂ , respectively. Signals a2A and b3B are passed to the I1 and I2 inputs of a first 180° combiner ₁₃₄₁ of the type described earlier. Signals b2B and a3A are passed to the I1 and I2 inputs of the second combiner ₁₃₄₂ . The combiners 134 ₁ and 134 ₂ have a differential output D which is connected as input to third and fourth splitters 124 ₃ and 124 ₄ which respectively generate two-way split signals, The above output signal is divided into fractional parts c1/c2 and d1/d2, respectively. The combiners ₁₃₄₁ and ₁₃₄₂ also have a summing output S which is connected to the I1 input of the third and fourth combiners ₁₃₄₃ and ₁₃₄₄ , respectively.

Output signals from the first and second phase shifters 128 ₁ and 128 ₂ are sent to fifth and sixth splitters 124 ₅ and 124 ₆ , which generate three-way splitters 124 ₅ and 124 ₆ respectively. Splitting the signal, splitting the above output signal into fractional parts e1/e2/e3 and f1/f2/f3 respectively. The output signal from the third splitter 124 ₃ is sent (fractional part c1 ) to the I1 input of the fifth combiner 134 ₅ and sent (fractional part c2 ) to the third φ-fill phase shifter 128 ₃ . The output signal from the fourth splitter 124 ₄ is sent (fractional part d1 ) to the I1 input of the sixth combiner 134 ₆ and sent (fractional part d2 ) to the fourth φ-fill phase shifter 128 ₄ . The output signal from the fifth splitter ₁₂₄₅ is passed (fraction part e1) to the I2 input of the fifth combiner ₁₃₄₅ , and is passed (fraction part e2) to the fifth φ filling phase shifter ₁₂₈₅ , and to the (fraction part e1) Part e3) to the I2 input of the fourth synthesizer ₁₃₄₄ . The output signal from the sixth splitter ₁₂₄₆ is passed (fraction part f1) to the I2 input of the sixth combiner ₁₃₄₆ , and is passed (fraction part f2) to the sixth φ filling phase shifter ₁₂₈₆ , and to the (fraction Part f3) to the I2 input of the third synthesizer ₁₃₄₃ . Through respective fixed phase shifters (PS) 136 ₁ to 136 ₁₂ , antenna elements 122 ₁ to 122 ₁₂ are connected from third to sixth combiners 134 ₃ , 134 ₆ and third to sixth phase shifters 128 ₃ , 128 ₆ The outputs of the receive drive signals as described in Table 3 below.

table 3 element synthesizer or phaser signal amplitude 122 ₁ Synthesizer 134 ₆ , output D 0.5d1(b2B-a3A)-0.707b1f1B 122 ₂ Phase shifter 128 ₄ 0.707d2(b2B-a3A) 122 ₃ synthesizer 134 ₆ , output S 0.5d1(b2B-a3A)+0.707b1f1B 122 ₄ Phase shifter 128 ₆ b1f2B 122 ₅ Synthesizer 134 ₄ , output D 0.5(b2B+a3A)-0.707a1e3A 122 ₆ synthesizer 134 ₄ , output S 0.5(b2B+a3A)+0.707a1e3A 122 ₇ synthesizer 134 ₃ , output S 0.5(a2A+b3B)+0.707b1f3B 122 ₈ Synthesizer 134 ₃ , output D 0.5(a2A+b3B)-0.707b1f3B 122 ₉ Phase shifter 128 ₅ a1e2A 122 ₁₀ synthesizer 134 ₅ , output S 0.5c1(a2A-b3B)+0.707a1e1A 122 ₁₁ Phase shifter 128 ₄ 0.707c2(a2A-b3B) 122 ₁₂ Synthesizer 134 ₅ , output D 0.5c1(a2A-b3B)+0.707a1e1A

Since all terms a1 to f3 are fractional, all signal powers are in terms of the fractional parts of the signal vectors A and B input to the first and second splitters ₁₂₄₁ and ₁₂₄₂ , respectively.

Phase shifters 128 ₁ to 128 ₆ provide compensation for the phase shift that occurs in the combiner (eg, 134 ₁ ). Thus, signals or signal components not transmitted via one or more combiners pass through two phase shifters (eg 128 ₁ ) before reaching the antenna elements 122 ₃ and 122 ₉ and receive a phase shift of 360°. Additionally, a signal or signal component transmitted via a combiner passes through a phase shifter (eg 128 ₄ ) before reaching the antenna element (eg 122 ₂ ) and receives a relative φ phase shift.

Table 4 Splitter splitter output Splitter split ratio Voltage decibel 124 ₁ , 124 ₂ a1A, b1B 0.4690 -6.58 a2A, b2B 0.8290 -1.63 a3A, b3B 0.3040 -10.34 124 ₃ , 124 ₄ 0.707c1(a2A-b3B), 0.707d1(b2B-a3A) 0.800 -1.94 0.707c2(a2A-b3B), 0.707d2(b2B-a3A) 0.600 -4.43 124 ₅ , 124 ₆ a1e1A, a1e3A, b1f1B, b1f3B 0.2357 -12.55 a1e2A, b1f2B 0.9428 -0.51

Table 4 gives the splitter ratios; the magnitudes (voltages) are calculated based on power normalized to 1 watt.

Referring now also to FIG. 8 , there is shown a vector diagram of the antenna system 120 when the phase difference between the input signal vectors A and B is 60°, where, in this embodiment, the angle of the antenna array 122 is The phase front is optimized. The antenna element drive signals are represented in magnitude and phase by solid radial arrows with antenna element reference numbers 122 ₁ to 122 ₁₂ and signal power (eg a1e2A). Components of the above signal (eg a1e1A) are represented by dotted or dashed vectors. The signals b1f2B and a1e2A on the respective antenna elements ₁₂₂₄ and ₁₂₂₉ are fractional forms of the input signal vectors A and B, and are in phase with the input signal vectors A and B, and they are separated in phase by 60°, such as by two as indicated by the double-headed arrows, where each double-headed arrow is labeled 30°. This figure contains complete information about signal amplitude and phase and will be further described below.

Referring now to FIG. 9, there is shown an antenna system 150 of the present invention employing a phased array 152 of two variable delay n elements ₁₅₂₁ to _152n , where n is an arbitrary positive integer. The first splitter 154 ₁ receives an input signal Vin and splits it into two signals, one of which has twice the power of the other. Of the two signals, the higher power signal is sent to the first variable phase shifter 156 ₁ , while the lower power signal is sent to the first fixed phase shifter 158 ₁ . The first fixed phase shifter 158 ₁ provides an output signal to the second splitter 154 ₂ via the second fixed phase shifter 158 ₂ , and the second splitter 154 ₂ divides the above output signal into n signal fractional parts a1 to an for output via the bus indicated by channel P. The first variable phase shifter 156 ₁ provides _an output signal to a third splitter 154 ₃ which splits the above output signal into n signal fractional parts b1 to bn. The signal fractional parts b2 to bn are output via the third fixed phase shifter ₁₅₈₃ and the bus denoted by channel Q. The signal fraction b1 has the same power as the signal sent to the first fixed phase shifter 158 ₁ and the signal fraction b1 is sent to the second variable phase shifter 156 ₂ and from there to the fourth branch 154 ₄ , the fourth splitter 154 ₄ divides the above-mentioned output signal into n signal fractional parts c1 to cn for output via the bus represented by channel R. The buses represented by channels P, Q, and R have Na, Nb, and Nc respective wires, respectively.

The fractional portions of the signal on channels P, Q and R are passed to a signal combining and phase shifting network, indicated generally at 159 . The network 159 is similar to the network described with reference to FIGS. 3 and 4 and will not be described further below. It has the function of combining and phase shifting the signals to produce the antenna element drive signals which are appropriately varied for the phased array 152 . The use of two variable phase shifters 156 ₁ and 156 ₂ is not necessary, but it increases the range of tilt angles in which the antenna can be electrically tilted compared to using only one variable phase shifter as described above. If a wider range of tilt angles is desired, Figure 9 can be extended with an additional variable phase shifter and splitter combination: i.e., just as b1 is variable phase shifted at 156 ₂ and split at 154 ₄ , c1 can is variably phase shifted and split to produce d1 to dn, d1 can be variably phase shifted and split to produce e1 to en, and so on.

Referring now to FIG. 10 , there is shown an antenna system 170 of the present invention for a phased array 172 of ten elements 172 ₁ to 172 ₁₀ using banked dual variable delays. This is a variation of the system 150 described with reference to FIG. 9 . The first splitter ₁₇₄₁ receives the input signal Vin and splits it into two signals, one of which has twice the power of the other. Of the two signals, the higher power signal is sent to the first variable phase shifter 176 ₁ and the lower power signal is sent to the first -180° phase shifter 178 ₁ . The signal delivered to the first phase shifter ₁₇₈₁ is labeled as vector A. It provides an output signal to the second splitter 174 ₂ which splits the above output signal into 4 signals a1A to _a4A .

The first variable phase shifter 176 ₁ provides an output signal to the third splitter 174 ₃ , which splits the output signal into two signals whose amplitude _is equal to that of the vector A: One of the two signals is denoted as _vector B and this signal is passed to a fourth splitter 174 ₄ which splits the aforementioned output signal into 3 signals b1B to b3B. The other of these two signals is transmitted to the fifth splitter 174 ₅ through the second variable phase shifter 176 ₂ , and this other signal is denoted as vector C, and the fifth splitter 174 ₅ converts the above The output signal is divided into three signals c1C to c3C.

Signals b1B and c1C are transmitted to antenna elements 172 ₃ and 172 ₈ via antenna phase shifters 182 ₃ and 182 ₈ , respectively. Signals b2B, b3B, c2C and c3C provide I1 input signals respectively to first, second, third and fourth 180° combiners 180 ₁ , 180 ₂ , 180 ₃ and 180 ₄ of the type described earlier. These synthesizers provide signal combining networks. Signals a1A to a4A respectively provide I2 input signals to these synthesizers. Antenna _elements 172 ₁ , _{172 2 ,} 172 _{4 to} 172 ₇ , 172 ₉ and _{172 10} from _the combiner The outputs of 180 ₁ to 180 ₄ receive drive signals whose magnitudes are shown in Table 5 below, and the drive signals for elements 172 ₃ and 172 ₈ are added to the table. N/A here means not used.

table 5 antenna element synthesizer output signal amplitude 172 ₁ synthesizer 180 ₂ , output S 0.707(b3B+a2A) 172 ₂ synthesizer 180 ₁ , outputs S 0.707(b2B+a1A) 172 ₃ N/A b1B 172 ₄ Synthesizer 180 ₁ , output D 0.707(b2B-a1A) 172 ₅ Synthesizer 180 ₂ , output D 0.707(b3B-a2A) 172 ₆ synthesizer 180 ₄ , output S 0.707(c3C+a4A) 172 ₇ synthesizer 180 ₃ , output S 0.707(c2C+a3A) 172 ₈ N/A c1 172 ₉ Synthesizer 180 ₃ , output D 0.707(c2C-a3A) 172 ₁₀ Synthesizer 180 ₄ , output D 0.707(c3C-a4A)

Values for splitter split ratios are given in Table 6 below, where the voltage was calculated from power normalized to 1 Watt as previously described.

Table 6 Splitter splitter output Splitter split ratio Voltage decibel 174 ₂ a1A, a3A 0.3162 -10.00 a2A, a4A 0.6324 -3.98 174 ₄ b1B, b2B, b3B 0.577 -4.78 174 ₅ c1C, c2C, c3C 0.577 -4.78

Variable phase shifters ₁₇₆₁ and ₁₇₆₂ are grouped, indicated by arrows and dashed lines, so that they can be changed together and give the same phase shift. They are all controlled by the inclination control mechanism 186 .

It can be seen from FIG. 10 that only the upper half of the _array 172 (antenna elements 172 ₆ to 172 ₁₀ ) receive signal components associated with the fractional portion _c1 etc. and 176 ₂ experience two variable phase shifts. Also, only the lower half of array 172, antenna elements ₁₇₂₁ to ₁₇₂₅ , receive signal components associated with fractional part b1 etc. from fourth splitter ₁₇₄₄ , which undergo a variable phase at ₁₇₆₁ shift. These two halves of array 172 (except antenna elements 172 ₃ and 172 ₈ ) receive signal components a1A, etc. from second splitter 174 ₂ , which components do not experience the variable phase shift at 176 ₁ or 176 ₂ .

Referring now to FIG. 11, the antenna system of the present invention can be implemented as a single feed line system or a dual feed line system. In a single feeder system, a single signal input 200 provides a signal Vin via one feeder 202 to an antenna arrangement 204 which may be mounted on a mast with an antenna array 206 . Signal splitting, variable and fixed phase shifting, and vector combining as described earlier are performed within the device 204 on the mast. This has the advantage that only one signal feed must be passed from the remote user to the antenna system, but conversely, the remote operator cannot adjust the angle of electrical tilt without accessing the antenna assembly 204 on the mast. Likewise, operators sharing a single antenna will all have the same electrical tilt.

FIG. 12 shows the antenna system of the present invention implemented as a dual feeder system 210 . The system has a tilt control unit 212 which, as previously described, generates two signals V2A and V2B and these signals are fed to an antenna array 216 via respective feed lines 214A and 214B. The tilt control component 212 may be located remote from the antenna array 60 and the user of the antenna mast mounting the antenna array, while the antenna feed network 218 (see, eg, FIG. 4 ) may be with the antenna array 216 . Signal splitting, fixed phase shifting (or other variable phase shifting if desired) and vector combining as described earlier are performed within means 216 . Users can now directly access the tilt control component 212 to adjust the angle of electrical tilt away from the antenna array 60 and mast, and can make this adjustment independent of other users sharing the antenna assembly 216 .

In dual feeder installations, it may also be convenient to reduce the tilt sensitivity to mitigate the effects of phase differences between the feeds, such as the difference between the electrical tilt desired by the operator and the desired electrical tilt at the antenna. Due to the respective tilt control components 212 located at each operator, and on the input side of the frequency selective combiner located at the operator's base station, a shared antenna system can be implemented in an individual tilt manner for each operator.

Figure 13 shows a phased array antenna system 240 of the present invention equivalent to that shown in Figure 3, with modifications so that it can be used in both receive and transmit modes. Components already described previously have similar reference numbers, but here have a prefix of 200, and only the changed components are described below. The variable phase shifter 246 for controlling the tilt is only used in transmit (Tx) mode at the moment and is connected in transmit path 243 between bandpass filters (BPF) 245 and 247 in series. There is also a similar receive (Rx) path 249 with a variable phase shifter 251 connected in series between bandpass filters 253 and 255 and a low noise amplifier or LNA 257 . The transmit and receive frequencies are usually significantly different to allow them to be isolated from each other by bandpass filter 245 or the like.

There are other, largely equivalent, second transmit and receive channels 243f, 249f associated with a fixed phase shift ψ: these channels have similar reference numbers with the suffix f. The second transmit channel 243f has a fixed phase shifter 246f between bandpass filters 245f and 247f. The second receive channel 249f has a fixed phase shifter 251f and an LNA 257f between bandpass filters 253f and 255f.

In addition to operating in transmit mode, elements 242, 244, 252, 254, 256 and 258 to 265 have the ability to operate in reverse in receive mode, eg splitters becoming combiners. The only difference between the two modes is that in transmit mode feeder 265 provides the input and transmit channels 243 and 243f are traversed by the transmit signal from left to right, whereas in receive mode receive channels 249 and 249f are traversed from right Receive signals to the left pass through, and feed line 265 provides a combined output of these signals. Received signals are produced in circuits ₂₆₄₁ through _264n and 260 through 254 from phase shifted and combined antenna element signals produced by array 262 in response to signal reception from free space. System 240 is advantageous because it allows the electrical tilt to be adjusted independently and equally in both transmit and receive modes: this is generally (and disadvantageously) not possible due to the frequency dependence of the antenna system elements , this characteristic is also different at different transmit and receive frequencies.

Referring now to FIG. 14 , there is shown a phased array antenna system 300 of the present invention used by multiple (two) operators 301 and 302 of a single phased array antenna 305 in both transmit and receive modes. Parts that are equivalent to those previously described are numbered similarly, but here with a prefix of 300 . The figure has a number of different channels: equivalent components in the different channels are similarly referenced and have one or more suffixes: the suffix T or R indicates a transmit or receive channel, the suffix 1 or 2 indicates the first One or second operator 301 or 302, while the suffix A or B indicates an A or B channel. Omission of these suffixes from a reference number prefix (eg 342) means all items with the referenced prefix.

First, the transmission channel 307T1 of the first operator 301 will be described. The transmit channel has an RF input 342 that feeds a splitter 344T1 that splits the input between variable phase shifter 346T1A and fixed phase shifter 348T1B. Signals are passed from phase shifters 346T1A and 348T1B to bandpass filters (BPF) 309T1A and 309T1B in different duplexers 311A and 311B, respectively. Bandpass filters 309T1A and 309T1B have a bandpass center at the transmit frequency of the first operator 301, designated as Ftx1, as shown in the figure. The first operator 301 also has a receive frequency designated as Frx1, and likewise for the second operator 302 has Ftx2 and Frx2.

The first operator transmit signal at frequency Ftx1 output from the leftmost bandpass filter 309T1A is divided by the second equally derived operator transmit signal at frequency Ftx2 output from the adjacent bandpass filter 309T2A. A duplexer 311A is combined. These combined signals are transmitted along feeder line 313A to antenna tilt network 315 of the type described in the earlier embodiments, and from there to phased array antenna 305 . Likewise, the other first operator transmit signal at frequency Ftx1 output from bandpass filter 309T1B is separated from the similarly derived second operator transmit signal at frequency Ftx2 output from adjacent bandpass filter 309T2B. The second duplexer 311B combines. These combined signals are transmitted to the phased array antenna 305 along the second feed line 313B through the antenna tilt network 315 . Although using the same phased-array antenna 305, both operators can vary their electrical inclination transmit angle independently and remotely from the antenna 305, in each case only by individually adjusting a single variable phase shifter, That is, a variable phase shifter 346T1A or 346T2A.

Similarly, the received signal returning from the antenna 305 via the network 315 and feeders 313A and 313B is divided by duplexers 311A and 311B. These separated signals are then filtered to isolate individual frequencies Frx1 and Frx2 in bandpass filters 309R1A, 309R2A, 309R1B and 309R2B which provide signals to variable and fixed phase shifters 346R1A, 346R2A respectively , 348R1B and 348R2B. Then, the receiving angle of the electrical tilt can be adjusted by the operators 301 and 302 by adjusting their respective variable phase shifters 346R1A and 346R2A. For signals of more than two operators, it is possible to combine in transmission or separate in reception by means of duplicated elements: i.e. instead of the components with suffixes 1 and 2, there will be similar components with suffixes 1 to m, where, m is the number of operators.

FIG. 15 shows a phased array antenna system 470 of the present invention, which is largely identical to the system shown in FIG. 10 . The previously described components are similarly numbered, but here the prefix 400 is used instead of 100, and only the changes are described below. The system ₄₇₀ has a first splitter 474 ₁ that splits the input RF carrier signal at 473 into two parts, _one of which is sent to the first feeder 477 ₁ , while the other part goes directly to the second feeder 477 ₂ . The items 473 to ₄₇₇₂ are located in or near a cellular mobile radio base station (not shown). Feed lines 477 ₁ and 477 ₂ connect the base station to a remote radome 479 in which a second variable phase shifter 476 ₂ is placed.

The system 470 operates as described earlier with reference to Figure 10, except that the first and second variable phase shifters ₄₇₆₁ and ₄₇₆₂ are no longer grouped, but are instead adjusted independently. This system offers the advantage that an independent electrical inclination can be provided for each operator sharing an antenna 472 (using a frequency selective combination, such as that shown in Figure 14), but the range of inclination common to all operators is extended . In fact, the angle of the electrical inclination set by the second variable phase shifter 476 ₂ can conveniently be the average value of the individual inclinations of the electrical inclinations of all operators sharing the antenna 472 .

However, Figure 15 shows the adjustment of the second variable phase shifter ₄₇₆₂ within the radome 479, which could also be located remotely from the radome 479 using a servomechanism controller (not shown). Additional variable phase shifters may be added to antenna system 470 in accordance with the present invention to further expand the range of inclination angles common to all operators.

FIG. 16 shows a further embodiment of a phased array antenna system 500 of the present invention using an input splitter SP ₁ , parallel line couplers (PLC) SP ₂ and SP ₃ and a 180° loop combiner SP ₄ to SP ₁₁ and H ₁ to H ₆ . Here SP in SP ₁ etc. denotes a splitter, and H in H ₁ etc. denotes a combiner used as a summation and difference (SD) generator. Each of the synthesizers SP ₄ to SP ₁₁ and H ₁ to H ₆ has 4 ports, namely first and second input ports and first and second output ports, indicated by arrows in inward and outward directions respectively . The output ports of each of the SD generator synthesizers H ₁ to H ₆ are summing and difference outputs, denoted by S and D, respectively. Each port of the individual annular combiners SP ₄ to SP ₁₁ and H ₁ to H ₆ is separated by a distance of λ/4 from one port and 3λ/4 from the other port around the annular circumference in each case . Here λ is the wavelength of the signal Vin in the ring material.

Signals applied to the input ports of any of the ring synthesizers SP ₄ to SP ₁₁ and H ₁ to H ₆ are split into two components which pass respectively clockwise and counterclockwise around the ring which itself Circumference with (n+1/2)λ, where n is an integer: these components have relative magnitudes determined by the relative path impedances in the rings they pass through, which allows the splitter split ratio to be preset . The two signals received from each input port at a distance of λ/4 from the output port are in phase and are added together to give a summed output. The two signals received from each input port at a distance of λ/4 and 3λ/4 from the output port are out of phase and subtracted from each other to give a difference output. At the output port at a distance of λ/2 from the input port, the two signals received from one input via the clockwise and anticlockwise paths respectively are out of phase and will give zero results if the path impedances are equal: thus this is The two ports are separated by a distance of λ/2 from each other.

Each ring synthesizer SP ₄ to SP ₁₁ used as a splitter has a first input connected to receive an input signal (inwardly directed arrow) and a second input connected to a respective port T (matched load) end. This port T provides a zero input signal: thus, the ring synthesizers or splitters SP ₄ to SP ₁₁ divide the signals on their first inputs between their respective outputs with the respective splitter split ratio, The splitting ratio of the splitter is determined in each case by the impedance ratio between input and output.

In system 500, as in the previous embodiment, the input signal Vin is split by a first splitter SP ₁ into two equal signals, where the power of each signal relative to the input signal Vin is reduced to -3dB: thus forming A signal of is passed through the variable phase shifter 502 and can appear on the first feeder 504 as vector A. The other signal thus formed can appear as vector B on the second feeder 506; this can include a fixed phase shifter between the first splitter _SP1 and the second feeder 506 as described earlier (not shown).

Signal vectors A and B are passed as inputs to PLCs SP ₂ and SP ₃ respectively, each of which has two outputs O1 and O2 and a fourth terminal _T4 connected to a matched load T which provides a Zero input signal. Each PLC SP ₂ and SP ₃ produces from its input a signal at output O1 and O2 whose power is reduced to -0.12dB and -16.11dB respectively with respect to the input signal in each case. The two -0.12dB signals obtained from PLC SP ₂ and SP ₃ are respectively sent to the first input terminals of the fifth and eighth splitters SP ₅ and SP ₈ , but the -16.11dB signal is sent to the sixth and the first input of the seventh splitter SP ₆ and SP ₇ .

The fifth splitter SP ₅ splits its input signal into output signals whose power is reduced to -5.3dB and -1.5dB below the input signal respectively, and these output signals are sent to the fourth splitter SP respectively ₄ and the first input of the first SD generator H ₁ . Similarly, the eighth splitter SP ₈ splits its -0.12dB input signal into output signals of -5.3dB and -1.5dB below its input signal, and these output signals are sent to the ninth splitter SP ₉ and The first input of the second SD generator _H2 .

The fourth splitter SP ₄ divides its -5.42dB input signal into -1.68dB and -4.94dB output signals below its input signal: the -1.68dB output signal is sent to the fixed phase shifter PE4 through the line L4 and From there it is fed to the antenna element E4 of the 12-element antenna array E. For each fixed phase shifter/antenna element combination PEn/En (n=1 to 12) there is one of the aforementioned lines Ln: the connection of the line Ln to the fixed phase shifter PEn is not explicitly shown in order to avoid too many overlapping lines, However, it is denoted by "PEn" at the end of each line Ln in each case. The -4.94dB output signal from the fourth splitter _SP4 is fed to the second input of the second SD generator _H2 .

The ninth splitter SP ₉ splits its input signal into output signals of -1.68dB and -4.94dB below its input signal: wherein the -1.68dB output signal is sent to the antenna element E9 via the line L9 through the fixed phase shifter PE9 . The -4.94dB output signal is fed to the second input of the first SD generator _H1 . The sixth splitter SP ₆ is an equal splitter which generates two output signals both 3dB below its input signal: of these output signals one is fed to the fifth SD generator H ₅ One input terminal, while the other is sent to the first input terminal of the third SD generator _H3 . The seventh splitter SP ₇ is also an equal splitter which generates two output signals which are both 3dB below its input signal and which are sent to the fourth and sixth SD generators H ₄ and H ₆ respectively the first input terminal of . The first SD generator _H1 has a summing output S connected to a second input of the fourth SD generator _H4 . It has a difference output D connected to the input of a tenth divider _SP10 . Similarly, the second SD generator _H2 has a summing output S connected to a second input of the fifth SD generator _H5 . It has a difference output D connected to the input of an eleventh splitter _SP11 .

The tenth splitter SP ₁₀ is an equal splitter which generates two equal output signals each 3dB below its input signal from the first SD generator H ₁ . One of these output signals is sent to the antenna element E2 via the line L2 through the fixed phase shifter PE2. The other of these output signals is fed to the second input of the third SD generator _H3 . Likewise, the eleventh splitter SP ₁₁ is also an equal splitter, generating two equal output signals both 3dB below its input signal from the second SD generator _H2 . One of these output signals is sent to the antenna element E11 via the line L11 through the fixed phase shifter PE11, while the other of these output signals is sent to the second input of the sixth SD generator _H6 .

The third to sixth SD generators _H3 to _H6 have a summation output S and a difference output D, which respectively pass through lines L1, L3, L5 to L8, L10 and L12 and fixed phase shifters PE1, PE3, PE5 to PE8, PE10 and PE12 provide drive signals to antenna elements E1, E3, E5 to E8, E10 and E12. A direct comparison of the power of the input signal Vin with the signal power received by the antenna elements can be obtained by adding the indicated dB values for each signal path (neglecting losses in non-ideal elements): for example, antenna element E4 receives a signal, The signal has been reduced to -3dB, -0.12dB, -5.3dB and -1.68dB compared to the input power at splitters SP ₁ , SP ₃ , SP ₅ and SP ₄ respectively, while the total power has been reduced to -9.1dB. The relative phases of the antenna element drive signals will not be described as the analysis is similar to that given in the previous embodiments.

The embodiment of the invention described above uses a 180° combiner. They could be replaced by e.g. a 90° "quadrature" combiner, with an additional 90° phase shifter to get the same full functionality, but this is less practical.

Embodiments of the invention have been described based on series-connected splitters and combiners, abbreviated as (S-H). Starting from these splitters and combiners, other embodiments of the invention are conceived with more stages, such as S-H-S, S-H-S-H, and so on.

Claims (30)

1. A phased array antenna system having adjustable electrical inclination and comprising an array of antenna elements, the system comprising: a) a variable phase shifter for introducing a variable relative phase shift between the first and second radio frequency signals; b) splitting means for splitting the relatively phase-shifted first and second signals into component signals, and c) a signal combining network, which is used to form a vectorial combination of these component signals to provide each individual antenna element with its own drive signal, which has an appropriate phase adjustment relative to the other drive signals, so that the electrical The tilt angle is adjustable in response to changes in the variable relative phase shift introduced by the variable phase shifter. 2. A system according to claim 1, having an odd number of antenna elements. 3. A system according to claim 1, wherein the variable phase shifter is a first variable phase shifter, and the system comprises a phase shifter arranged to phase shift the component signal which has been phase shifted by the first variable phase shifter A second variable phase shifter that provides additional component signal outputs for the signal combining and phase shifting network either directly or through one or more splitter/variable phase shifter combinations. 4. The system of claim 1, wherein the variable phase shifter is one of a plurality of variable phase shifters, and the signal phase shifting and combining network is arranged to generate the antenna element drive signal from the component signals, said Some of the component signals have gone through all the variable phase shifters and some have not. 5. A system according to claim 1, wherein the splitting means is arranged to split the component signal into further component signals for input to the signal phase shifting and combining network. 6. The system of claim 1, wherein the signal phasing and combining network uses phase shifters and 3dB directional couplers (combiners) for phase shifting and vector combining of the component signals. 7. The system of claim 6, wherein said combiner is a 180 degree combiner. 8. The system according to claim 6, wherein said combiner is a ring combiner having a circumference of (n+1/2)λ and adjacent ports separated by λ/4, where λ is the configuration The wavelength of the RF signal in the material of each loop combiner. 9. A system according to claim 8, wherein the branching means comprises a circular combiner having a circumference of (n+1/2)λ and adjacent input and output ports separated by λ/4, each combiner One of the input ports is terminated with a resistor equal to the system impedance and forming a matched load. 10. A system according to claim 6, wherein the combiner is designed to convert the input signals I1 and I2 into vector sums and vector differences other than (I1+I2) and (I1-I2). 11. The system of claim 1, wherein the branching means, the variable phase shifter and the signal phase shifting and combining network are co-located with the antenna array as an antenna assembly, and the assembly has a single radio frequency input power feed from a remote source electric wire. 12. The system according to claim 1, wherein the splitting means comprises first, second and third splitters, the first splitter and the variable phase shifter remote from the second and third splitters are mounted on together, and the second and third splitters, the signal phase shifting and combining network, and the antenna array are co-located as an antenna arrangement, and the arrangement has dual radio frequency input power feeds from distant sources, the first splitter and the second A variable phase shifter is located at the remote source. 13. The system of claim 1, wherein the variable phase shifter is a first variable phase shifter connected in the transmit path, and the system includes other transmit and receive phase shifters connected in the receive path and providing fixed phase shifts. channel, and is arranged by generating antenna element drive signals in response to signals in the transmit channel, and generating receive channel signals from signals formed by the antenna elements operating in the receive mode The signal phasing and combining network operates in both transmit and receive modes, with independently adjustable electrical tilt in each mode. 14. A system according to claim 1, wherein the variable phase shifter is one of a plurality of variable phase shifters associated with each operator, and the system includes filtering and combining means for The signal is routed to a common signal feed after phase shifting in a phaser, which is connected to a splitting device and a signal combining and phase shifting network to provide a signal to an antenna comprising Operator influence of tuned electrical inclination. 15. The system of claim 14, wherein the plurality of variable phase shifters includes a pair of respective variable phase shifters associated with each operator, and the system has both forward and reverse signal processing capable components to allow the system to operate in both transmit and receive modes, with independently adjustable electrical tilt in each mode. 16. A method of adjusting the electrical tilt of a phased array antenna system, the system comprising an array of antenna elements, the method comprising: a) introducing a variable relative phase shift between the first and second radio frequency signals, b) splitting the relatively phase-shifted first and second signals into component signals, and c) Vector combining and relative phase shifting of these component signals to provide each individual antenna element with its own drive signal with appropriate phase adjustment relative to the other drive signals so that the electrical tilt response of the array Adjustments can be made for changes in the variable relative phase shift. 17. The method of claim 16, wherein the array has an odd number of antenna elements. 18. A method according to claim 16, which includes generating at least one component signal which has undergone a phase shift in a plurality of variable phase shifters. 19. A method according to claim 18, wherein said variable phase shifters are grouped, the method comprising generating antenna element drive signals from component signals, some of which have passed through all the variable phase shifters, and wherein Some don't. 20. A method according to claim 16 which includes splitting one component signal into other component signals for input to a signal phase shifting and combining network. 21. The method of claim 16 using phase shifters and combiners to phase shift and vector combine component signals. 22. The method of claim 21, wherein said combiner is a 180 degree combiner. 23. The method of claim 21, wherein said combiner is a ring combiner having a circumference of (n+1/2)λ and adjacent input and output ports separated by λ/4 , where n is an integer and λ is the wavelength of the radio frequency signal in the material from which each ring combiner is constructed. 24. A method according to claim 23, wherein the branching means comprises a ring combiner having a circumference of (n+1/2)λ and adjacent input and output ports separated by λ/4, One input port of each ring synthesizer is terminated with a resistor equal to the system impedance and forming a matched load. 25. The method according to claim 23, wherein the combiner is designed to convert the input signals I1 and I2 into vector sums and vector differences other than (I1+I2) and (I1-I2). 26. A method according to claim 16 which includes feeding a single radio frequency input signal from a remote source for signal separation, variable phase shifting and vector combining in a network co-located with the antenna array to form the antenna arrangement. 27. A method according to claim 16, comprising feeding two radio frequency input signals from a remote source to the antenna arrangement and performing signal separation, variable phase shifting and vector combining in a network co-located with the antenna array, wherein The two radio frequency input signals have variable phases relative to each other. 28. A method according to claim 16, characterized in that it uses a transmit and receive channel to operate in both a transmit mode and a receive mode, and that it comprises generating an antenna element drive signal in response to a signal in the transmit channel, and generating a receive channel signal from the signal formed by the antenna elements operating in the receive mode, with independently adjustable electrical inclination in each mode. 29. The method of claim 16, wherein the variable phase shifter is one of a plurality of variable phase shifters associated with each operator, and the method comprises: a) after phase shifting in the individual variable phase shifters, the signals are filtered and combined and delivered to a common signal feed means connected to the splitting means and to the signal combining and phase shifting network; b) provide signals to antennas containing influences from both operators; and c) Independent adjustment of the electrical tilt associated with each operator. 30. The method of claim 29, wherein the plurality of variable phase shifters includes a pair of respective variable phase shifters associated with each operator, the method using both forward and reverse signal processing capability, and the method includes operation in transmit and receive modes with independently adjustable electrical inclination in each mode.

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