SE519587C2 - delay circuit - Google Patents

Abstract

An electronic circuit with at least one active electronic component (10) and a delay element connected to the component. The delay element comprises an electric conductor (13, 18) which is composed of a conductive material on an insulating layer (14) such that the conductor's capacitive coupling to the surrounding becomes low. The conductor (13, 18) is drawn such that its inductance is minimized. The electronic component (10) and conductor (13, 18) are integrated in an integrated circuit. Conductor (13, 18) is drawn in loops of some length, and ground conductor (35) of some length conected to a ground plane is provided between the loops. The delay element can be used in an oscillator coupling or in an electronically controlled antenna. In the oscillator coupling the electronic component (10) comprises an inverter coupling (11) with an input (11) and an output (12). The conductor (13) is provided to connect input (11) to output (12), thus creating an oscillator. The electronically controlled antenna comprises a receiver (17) and a number of antenna elements (16) connected to the receiver (17). Individual antenna elements (16) are connected to the receiver (17) via automatically selectable delay elements (18) such that electric signals from different antenna elements (16) are differentially delayed dependent on the position of the antenna elements in relation to the impinging electromagnetic wave fronts.

Description

25 30 | - r .. ». u -. .v o - -. . . . . t. . ...

. -, I ... . .-; . u. n. n »n, ... n .... 1. . -. . s v> ~. . . .t ... . . The most common type of antenna in this context is the satellite dish. However, so-called electronically controlled antennas or phase matrix antennas are becoming more common.

A phase matrix antenna comprises a group of equal radiating elements. By controlled feeding of the elements through a pipe network, so that they cooperate in phase, a lobe with good directing action can be achieved. The wiring network may also include electronically controlled phase changers and possibly amplifiers, one for each element, whereby the direction of the ioben can be varied, without the need for mechanically moving components.

The electronically controlled phase transmitters are complicated and expensive devices, which is why this type of antenna has not been widely distributed commercially. Another factor that limits the use of the antenna type is the frequency dependence of the phase changes. The main area of use for phase matrix antennas is within the radar range.

SUMMARY OF THE INVENTION An object of the invention is to provide an electronic circuit which can be embodied in a simple manner and which can be combined with other circuits in integrated form. The electronic circuit enables electronic delay of an electrical signal. This object is achieved by the invention obtaining the features stated in claim 1.

According to one aspect of the invention, an oscillator has been provided, which in all parts is realizable in integrated form. According to a further aspect of the invention, an electronically controlled antenna has been provided which lacks the disadvantages of the phase transmitters. Electrical signals from individual antenna elements are delayed differently depending on the position of the antenna elements in relation to incident electromagnetic wavefronts. Based on an array of antenna elements, which are distributed over a surface, it is possible to selectively delay the signal from individual antenna elements and thereby influence in which direction the antenna should be sensitive. The delay is suitably provided in integrated circuits arranged in connection with the antenna elements. According to one embodiment, an upp- AH 99005495 99-04-21 ver. 18 10 15 20 25 30 519 58Z: g¿; ¿y; ¿ïnH * 3 installation of conductors of different lengths arranged between the antenna elements and a receiver unit. A conductor of a certain length is connected by a control unit depending on the position of the antenna element in relation to an incoming wavefront of an electromagnetic wave. Said position detectably affects properties of the electrical signals received. The set of conductors and the control unit are together with other electronic components gathered in a cell unit. The conductor is made in integrated form on an insulating layer.

Additional advantages and features of the invention will become apparent from the following description, drawings, and dependent claims.

BRIEF DESCRIPTION OF THE INVENTIONS The invention will now be described in more detail with the aid of exemplary embodiments with reference to the accompanying drawings, in which Fig. 1 schematically shows an embodiment of an electronic circuit according to the invention in the form of an oscillator, Fig. 2 Fig. 3 schematically shows a distributed resistance and capacitance of conductors, is a diagram as the delay of a conductor depending on the length of the conductor, Fig. 4 is a basic block diagram showing an alternative embodiment of an electronic circuit according to the invention in the form of a cell unit with peripheral equipment of an antenna Fig. 5 shows in principle how several cell units are arranged on a portion of an antenna surface, Fig. 6 schematically shows an embodiment of a delay element in the form of a conductor which forms part of the invention, Fig. 7 schematically shows an embodiment of a conductor which can be connected in different lengths Fig. 8 is a basic circuit diagram showing a component included in an electronic circuit according to the invention, among others FIG. 9 schematically shows a portion of a long conductor according to the invention with intermediate ground wires, AH 990054pS 99-04-21 Ver. FIG. 10 FIG. 11 FIG. 12 FIG. 13 FIG. 14 FIG. 15 FIG. 16 FIG. 17 FIG. 18 519 587 showing an analog amplifier included in an electronic circuit according to the invention, is a cross-sectional view showing a chip with conductors according to an embodiment of the invention, is a diagram showing electromagnetic field curves around conductors arranged in a dielectric with the dielectric constant a = 35 in a delay circuit with earth conductors according to the invention, a diagram showing electromagnetic field curves around conductors arranged in a dielectric with the dielectric constant e = 3.9 in a delay circuit with earth conductors according to the invention is a diagram showing electromagnetic field curves around conductors arranged in a dielectric with the dielectric constant e = 1 in a delay circuit with earth conductor according to the invention, is a diagram showing electromagnetic field curves around conductors arranged in a dielectric with the dielectric constant s = 35 in a delay circuit without earth conductor, is a diagram showing electromagnetic field curves around conductors arranged in a dielectric with the dielectric constant s = 3.9 in a delay circuit without earth conductor, and is a diagram showing electromagnetic field curves around conductors arranged in a dielectric with the dielectric constant s = 1 in a delay circuit without earth conductor.

THE INVENTION In the embodiment according to FIG. 1, an inverter connection 10 is schematically shown, the input 11 of which is connected to its output 12 via a long conductor 13. For a conductor of length! the period time T is given by the following formula where vc is the electromagnetic propagation speed in the conductor.

AH 990054ps 99-04-21 ver. 'lB 10 15 20 25 s- nu s s u .f n. .i 1; g. -. v l a e. a g ~. t. u u a, 1 .u i »g. i .. m ... | .. r ~ | -j. ; l v - v,. ... . l. 1. 5 T = _c (1) With vC = 200 000km / s and an assumed length l of 0.5 m, the frequency becomes 200MHz. This is provided that the delay in the inverter connection itself is of the order of a few picoseconds. With low spread in the inverter connection delay, e.g. 10% is the inaccuracy in the same class as for a crystal oscillator. This length, which is required for the desired delay to be achieved, in many cases acts as a deterrent. The actual delay of the conductor is also dependent on the distributed resistance of the conductor and the distributed capacitance of the conductor.

In an ideal conductor, any variation in period time and thus in frequency depends only on the performance of the inverter connection. If the delay of the inverter coupling 10 is small relative to the delay in the conductor 13, which is dependent primarily on the length of the conductor, the accuracy of the inverter coupling has very little effect. The conductor is made as a metal conductor in an integrated process, e.g. a CMOS process.

The conductor 13 is made with the width w and rests on some form of insulating layer 14. The insulating layer usually comprises both metal oxide and field oxide and has the thickness b. The dielectric constant of the insulating layer affects the choice of the dimensions of the conductor and other components. The larger the dielectric constant of the insulating layer, the smaller dimensions can be selected.

A semiconductor material 15, e.g. silicon, surrounds the party occupying the conductor. In the semiconductor material, the inverter coupling 10 and other semiconductor circuits can be made, giving these access to the oscillator.

In one embodiment, the insulating layer consists of silica. The insulating layer can also be made of glass or other ceramic material. As an alternative, the insulating layer can be designed as an air layer. In such an embodiment, the conductor rests on post-like formations, which are based on the semiconductor material used or the base material. ÅH 990054ps 99-04-21 var. 18 10 15 20 av nu - u -g .. - u -; ø 1. s. v a =. - -. . »A u 1 n. T .. f. T .. .ryvu v. v. | ,. . v - v .t .i n. t, 6 The conductor should be designed so that it gives rise to as little inductance as possible. Conveniently, the conductor runs in a loop with several parallel conductor portions, so that the current direction of adjacent conductor portions is opposite. It is also possible to make two parallel loops opposite phase or double loops. According to a particularly preferred embodiment, the conductor is made in two parallel running loops, one of which is fed with the signal to be delayed and the other is fed with the inverse of the signal, see Fig. 7 and Fig. 9. This minimizes the effect of several different forms of disturbances.

In a real conductor, a time delay occurs depending on the conductor's distributed resistance and the conductor's distributed capacitance according to the formula below. The distributed properties can be illustrated according to FIG. 2. The total length of the conductor is !. In Fig. 2, the total capacitance of the C conductor and the total resistance of the R conductor. The pluralist is generally given by the following formula: pl pl K, -l: ízíz 2 RA aw W darK, = - and A -l C = 8-í = 8-l / t -) _ = Kc-Wl (3) where KC The preforms apply to: s = the dielectric constant of the insulating (oxide) layer, p = the resistivity of the conductor material, a = the thickness of the conductor, b = the thickness of the insulating (oxide) layer and w = the minimum width of the conductor.

From the relationships above, the time delay is given: Il R C e tRC = 2- ~~ dan-m (4) 0 n n AH 99005405 99-04-21 ver. 18 10 15 20 25 519 537.m..H ... H ... H ....., M .M.H .... H. m-.H.-MHH ..

..... .HRS.

......HRS . 7 The time delay can be reformulated to the time delay in small time segments, whereby the following applies: Al 2 mm = mLM> K¿; k¿wAmKgm Q The previously used constants are hereby merged into a new constant Km, for which the following applies.

"DK -8 *" 'ab This constant is strongly temperature dependent and voltage dependent, so it should be minimized. It should be noted that the time delay does not depend on the line width of the process. feature.

The diagram in FIG. 3 shows with the curve tA the delay which depends on the propagation speed in the conductor. Kurvan tm; shows the delay due to the conductor's resistance R and capacitance C. The propagation speed v in the conductor cannot be affected to any appreciable extent. It can be shown that where c = the speed of light and s, = the dielectric constant of the material.

As can be seen from the above formulas, the effect of tRC becomes lower the thicker the insulating layer and the thicker the conductor used. The dashed line in FlG 3 shows how the curve tRC is affected when the insulating layer and the conductor are made thicker. By utilizing the area within which the impact of tm; is low, the stability of the oscillator can be good and its oscillation frequency is controlled substantially entirely by the length of the conductor. The insulating layer 14 is preferably made with a much greater thickness b than with the existing oxide layers. A suitable thickness exceeds 10 μm and is preferably in the range 10-100 μm, if the oscillator is to be used at frequencies around 1GHz. A thickness b suitable for many applications is 20 μm. With increasing value of b, other dimensions can also increase. Of course, the final dimensions are also affected by external dimensional frames. Ledarens 13 AH 99005495 99-04-21 ver. 18 10 15 20 25 30 n- w. . ., .l -. n t .I l _ .t-. . ,. , .-. . . t .n n t at; m. - = t. ti »n .. o l f ~. u u w 1 I .., 8 thickness is in common processes of 1 μm, and an increase in the thickness, but not the width, improves the properties and performance of the oscillator.

The length of the conductor means that special consideration should also be given to inductive properties. It is therefore inappropriate to make the conductor in a spiral shape or the like. The length of the conductor should also be adapted to the desired oscillator wavelength. Suitably the length of the conductor is a multiple of half the wavelength, or preferably half the wavelength. In the embodiment according to Fig. 4, the invention comprises antenna elements 16, which are connected to a cell unit 22. The cell unit 22, which is marked with dashed lines in Fig. 4, comprises a set of individually connectable delay elements 18, through which a antenna element 16 is received. signal is passed on to a receiver unit 17 common to a plurality of cell units 22. The received signal is amplified in an amplifier 23.

The connection of the delay elements 18 is effected in the embodiment according to FIG. 4 by a demultiplexer 19 and a multiplexer 21. The delay elements 18 in the form of conductors connect the demultiplexer 19 and the multiplexer 21, and a single delay element 18 is connected by setting the demultiplexer 19 or / and the multiplexer 21. The setting is made by a control unit 20, which is connected to a central unit 24 common to several cell units 22.

To reduce problems with, among other things, residual capacitive and inductive coupling, the incoming signal can have a frequency of the order of 12 GHz, the incoming signal is suitably routed together with a signal from a local oscillator 25 to a mixer 26, see also FIG.

From the mixer 26, the signal suitably has a frequency in the range of a few GHz.

The various control units 20 and possibly the local oscillators 25 are connected to the central unit 24, preferably by a bus connection 27.

It may be appropriate for the central unit 24 to comprise means for synchronizing the various oscillators 25. The synchronization can also take place via the control unit 20. According to an alternative embodiment (not shown), the oscillator starts from the cell AH 990054ps 99-04-21 ver , 18 10 15 20 25 30 .i -tg H., ,, It »nu. . .. .. ,, §g ~ - =., É .t,,, - '~. n »u ß x u i | o v "i -. __ 9 unit. Instead, a common oscillator is arranged, preferably in the central unit. The design of the oscillator used should be adjustable for different frequency bands.

All components included in the cell unit 22 can be made integrated in semiconductor materials. The semiconductor process used should be selected taking into account high frequency characteristics, especially with respect to amplifier 23, and the characteristics affecting the conductors that may be included in the delay elements. The noise factor should be in the order of 0.5 dBu. lvlycket low capacitive connections should be sought. The conductor is made as a metal conductor in an integrated process, e.g. a CMOS process.

The receiver unit 17 can be designed in a conventional manner as a satellite receiver. It happens that satellite receivers are equipped with control means for motor control of a conventional satellite dish. The receiver unit 17 comprises similar control means, and a control output 28 transmits control information to the central unit 24. The control information may include instructions to sweep with the electrically controlled antenna over a certain space angle in connection with finding a new transmitter. When a transmitter is found, the control information will continuously control the setting of the antenna, so that the transmitter can be followed, if the antenna is physically angled or moved in relation to the transmitter. A signal line 29, preferably from each of the cell units 22, directs a received antenna signal to the receiver unit 17. The quality and certain characteristics of the antenna signal affect how the central unit 24 is to be controlled to in turn affect the various control units 20 of the cell units 22. The number of delay elements 18 which are required for the desired possibilities for fine tuning of the antenna to be achieved varies with the current application. For standard satellite reception applications, a few hundred delay elements 18 should be sufficient. The characteristics of the amplifier 23 also affect how many delay elements 18 are required. Due to the very good amplification properties and signal-to-noise ratio of the amplifier, the number of direction-setting delay elements 18 can be kept down.

An antenna made with components as above can be made as shown in FIG. 5. On a surface, a plurality of cell units 22 are arranged. Each AH 990054515 99-04-21 var. 18 10 15 20 25 30 519 587 t. «. n cell unit 22 years connected to four paired antenna elements 16A-16D.

Two opposing first antenna elements 16A and 16B are for receiving horizontally polarized signals, and two opposing second antenna elements 16C and 16D are for receiving vertically polarized signals. Other configurations can also be used to receive different signal types. Each antenna element 16A-16D can be a few millimeters long and wide and different shapes can occur. Suitably the antenna elements 16A-16D are made of metal. The external dimensions of the antenna can be appropriately assumed! antenna elements will be such that the surface of the antenna is in the order of 0.1-1.0 m2.

The bus connection 27 preferably runs through or past each cell unit 22. The various antenna elements 16A-16D can be connected to the amplifier 23 directly or via a multiplexer, which is then suitably controlled by the control unit 20.

Fig. 6 shows in principle how the conductors 18 can be designed. Each conductor 18 is made with the width w and rests on some form of insulating layer 14. The insulating layer usually comprises both metal oxide and field oxide and has the thickness b. A semiconductor material 15, e.g. silicon, surrounds the party occupying the leader. In the semiconductor material, the amplifier 23 and other semiconductor circuits can be made.

In one embodiment, the insulating layer consists of silica. The insulating layer can also be made of glass. As an alternative, the insulating layer can be designed as an air layer. In such an embodiment, the conductor rests on pole-like formations, which are based on the semiconductor material used or the base material.

An example of dual conductors with selectable delay is shown in FIG.

The signal S to be delayed is routed to a buffer or line amplifier 30. The inverse S 'of the signal is also routed to the line amplifier 30. Two parallel conductors emanate from the line amplifier 30, which together run a long loop. The total length of the loop can, as stated above, amount to the order of 0.5 m.

From each of the two parallel conductors 13, lead-out leads 31, 31 'lead at different distances from the line amplifier to a common output lead-AH 990054ps. 18 10 15 20 25 30 519 587 11 re 32 respectively 32 ”. Selection of conductor length and thus outlet line is made in a demultiplexer (not shown), which passes through control lines 33 and associated controllable gates 34 through the delayed signal. The signal that is delayed can be analog, e.g. in connection with an antenna of the type shown in FIG. 4 and FIG. 5, or digitally in connection with an oscillator or the like. The delay can be selected step by step, with each step corresponding to the conductor length between two outlet locations.

When the device according to the invention is used with antennas and receivers, a mixer 26 is usually used. An example of such a mixer 26 is shown in Fig. 8. Two counter-phase signals are taken from a local oscillator 25. The opposite phase signals are fed to a mixer 26, which in the embodiment shown comprises four MOS transistors.

A preferred embodiment of the conductor 13 is shown in FIG. 9. The conductor 13 runs in two parallel paths in elongate loops. The two paths are fed with signals in opposite phase. The circuit then becomes less sensitive to disturbances. In each loop a portion of a ground conductor 35 is arranged. Preferably, the ground conductor 35 runs centrally between two loops and substantially to the bottom of a loop. The earth conductor 35 is connected to a ground plane. The distance between two conductors in a loop is in the same order of magnitude as the distance between two loops. Suitably these distances are about 20 pm. The width of the conductor is in the order of half the said distance, or about 8 μm, see also Fig. 12. The total length of the conductor is determined by the current application and can be in the order of 0.5 m or greater. An earth conductor 35 can also be used, if the conductor 13 is designed as a single conductor.

Amplifiers can be arranged in different sections of the long conductor paths. A suitable embodiment of an amplifier for use in digital applications is shown in Fig. 10. Two two-input NAND gates 36 are connected via their outputs, so that switching in the gates takes place simultaneously. The signal is applied to the amplifier as an input signal S and its inverse S ”.

A corresponding amplifier for analog applications is shown schematically in FIG. 11. Also in this case, the amplifier is supplied with both the signal S and its inverse S ”.

AH 990054ps 99-04-21 ver. 18 10 15 20 25 30 519 587 <. . FIG. 12 schematically shows an example of what a chip with a delay element according to the invention can look like in section. Two conductors 13 in a loop are made with an intermediate distance D = 20 μm. In addition, a conductor in a loop portion runs parallel to an earth conductor 35 at substantially the same distance M = 20 μm. Both conductors 13 are designed so that they are enclosed by an insulating material 14. In the embodiment shown, the insulating material consists of silica. The silica layer 14 has a thickness which means that the distance N to an underlying clay layer amounts to 20 μm. The width of the conductors 13 amounts to approximately 8 μm, while the width of the earth conductor amounts to approximately 2 μm.

The distances mentioned are approximate and can vary depending on the application and selected material of the insulating layer 14. A glass layer 37 is arranged on top of the silicon oxide layer 14. If air is used as insulating material, the glass layer 37 can be removed.

FIG. 13 - FIG. 15 are diagrams schematically showing the propagation of electromagnetic fields around the conductors 13 when ground conductors 35 are used. A loop comprises the two central conductors 13, while the conductor 13 on the far right belongs to an adjacent loop. In the figures, a boundary line 38 indicates that two different dielectric constants occur. The conductors 13 and the earth conductors 35 are arranged completely immersed in the insulating layer. The solid field lines refer to the magnetic field and the arrows indicate electric field strength. The electric field strength at the feet of the arrows shall be proportional to the length of the arrows.

Above the boundary line 38, the dielectric constant s = 1, e.g. in the form of air. Below the boundary line 38 in the example in FIG. 13 the dielectric constant is s = 35. The figure shows that the earth conductor 35 helps to reduce the connection between the conductors in different loops. A higher dielectric constant also means the possibility of reducing the distance between the conductors without increased risk of interference.

In the example in FIG. 14, the dielectric constant s = 3.9 in the material below the boundary line 38. This dielectric constant has a suitable silicon dioxide layer selected.

In the example in FIG. 15, the conductors 13 and the earth conductors are arranged on pillars or the like in air, so that the dielectric constant s = 1 around the conductors.

AH 990054ps 99-04-21 ver. FIG. 16 - FIG. 18 are diagrams schematically showing the propagation of electromagnetic fields around the conductors 13 when earth conductors 35 are missing. Other conditions correspond to the examples in FIG. 13 - FIG. 15. In all three cases, it is clearly indicated that the risk of crosstalk and other disturbances between conductors in different loop sections increases when earth conductors are missing.

AH 990054pS 99-04-21 ver. 18

Claims (20)

10 15 20 25 30 519 587 14 PATENT REQUIREMENTS Electronic circuit with at least one active electronic component (10) and a delay element connected to the component, the delay element comprising an elongate electrical conductor (13, 18) drawn in elongate loops, characterized in that the conductor (13, 18) 18) is made of conductive material on an insulating layer (14), so that the capacitive connection of the conductor to the environment becomes low, the conductor (13, 18) is drawn so that its inductance is minimized, the electronic component (10) and the conductor (13, 18) are integrated in an integrated circuit, the conductor (13, 18) is drawn in the form of parallel conductor portions with reverse current direction in adjacent conductor portions and a longitudinal earth conductor (35) connected to a ground plane is arranged between the loops in the same plane as the loops. . Electronic circuit according to claim 1, characterized in that the insulating layer (14) consists of oxide material. Electronic circuit according to claim 1, characterized in that the insulating layer (14) encloses the conductor (13, 18). Electronic circuit according to claim 1, characterized in that the insulating layer (14) consists of air. Electronic circuit according to claim 1, characterized in that terminal lines (31) are connected to the conductor (13, 18) at certain intervals and the terminal lines (31) are connected via common gates (34) to common output conductors (32). . Electronic circuit according to claim 5, characterized by AH 990054pS.d0C 02-0208 ver. 20 10 15 20 25 30 519 587 15 - «. | n that terminal lines (31) are connected to the common output conductors (32) via line amplifiers (30) and that the line amplifiers (30) are made with higher gain the longer the conductor (13, 18) ran at the connection with the terminal line (31). Electronic circuit according to claim 1, characterized in that the thickness of the insulating layer (14) exceeds 20 μm. Electronic circuit according to claim 1, characterized in that the thickness of the conductor (13) exceeds 1 μm. Electronic circuit according to claim 1, characterized in that the electronic component (10) comprises an inverter connection with input (11) and output (12) and that at least one conductor (13) is arranged to connect the input (11). ) with the output (12) forming an oscillator. Electronic circuit according to claim 9, characterized in that the inverter connection (10) and the conductor (13) are made in a semiconductor process with semiconductor / metal on glass / ceramic. Electronic circuit according to claim 9, characterized in that the inverter coupling (10) is made of semiconductor material, Electronic circuit according to claim 9, characterized in that the inverter connection (10) is carried out in a process which comprises silicon on an insulator. Electronic circuit according to claim 1, characterized in that the length of the conductor (13) exceeds 0.2 m. Electronic circuit according to claim 1, comprising an electronically controlled antenna, a receiver unit (17) and a plurality of antenna elements (16) connected to the receiver unit (17), characterized in that 15. AH 990054ps.doc 02-02-08 ver. 20 10 15 20 25 30 att 15 att 16 att att 17 17 att att 1 8 att att 519 587 16. ». . .- individual antenna elements (16) are connected to the receiver unit (17) via automatically selectable delay elements (18), so that electrical signals from different antenna elements (16) are delayed differently depending on the position of the antenna elements (16) in relation to incident electromagnetic wavefronts . Electronic circuit according to claim 14, characterized in that the delay elements (18) comprise different length electrical conductors. 16.. Electronic circuit according to claim 14, characterized in that individual antenna elements (16) are connected to the delay elements (18) via a demultiplexer (19), individual antenna elements (16) are connected to the receiver unit (17) via a multiplexer (21) and the demultiplexer ( 19) is operatively connected to a control unit (20), so that a single delay element (18) is switched on depending on the characteristics of the received electrical signals. 17.. Electronic circuit according to claim 16, characterized by the demultiplexer (19), the multiplexer (21) and the control unit (20) are designed together with the delay elements (18) in a cell unit (22) designed as an integrated circuit and an antenna element (16) is associated with a cell unit (22). Electronic circuit according to claim 16, characterized by the receiver unit (17) is connected to a central unit (24) for transmitting control information for controlling the antenna and the central unit (24) is connected to the control units (20) associated with the antenna elements (16). . 18.. Electronic circuit according to claim 16, characterized in that individual antenna elements (16) are connected to a demultiplexer (19) via an amplifier (23). 19. AH 990054p $ .doc 0202-08 ver. 20 519 587 17 Electronic circuit according to claim 16, characterized in that individual antenna elements (16) are connected to demultiplexer (19) via a mixer (26) and that the mixer (26) is also connected to an oscillator (25). AH 990054ps.d0c 02-02-08 ver. 20