U.S. patent application number 11/843918 was filed with the patent office on 2008-07-24 for method and system for defence against surface-to-air missiles.
This patent application is currently assigned to DIEHL BGT DEFENCE GMBH & CO., KG. Invention is credited to Tilo Ehlen, Robert Stark, Jurgen Urban, Dieter Weixelbaum.
Application Number | 20080174469 11/843918 |
Document ID | / |
Family ID | 38561685 |
Filed Date | 2008-07-24 |
United States Patent
Application |
20080174469 |
Kind Code |
A1 |
Stark; Robert ; et
al. |
July 24, 2008 |
METHOD AND SYSTEM FOR DEFENCE AGAINST SURFACE-TO-AIR MISSILES
Abstract
A method and a system for defense against surface-to-air
missiles (Manpads), which represent a threat to military and civil
aircraft during takeoff and landing. For missile defense, the
missile is jammed by irradiating it with electromagnetic jamming
radiation. This jamming radiation may be constituted of
continuous-wave irradiation or frequency packets with a defined
pulse repetition rate.
Inventors: |
Stark; Robert; (Bad
Windsheim, DE) ; Urban; Jurgen; (Erlangen, DE)
; Ehlen; Tilo; (Munster, DE) ; Weixelbaum;
Dieter; (Nennslingen, DE) |
Correspondence
Address: |
SCULLY SCOTT MURPHY & PRESSER, PC
400 GARDEN CITY PLAZA, SUITE 300
GARDEN CITY
NY
11530
US
|
Assignee: |
DIEHL BGT DEFENCE GMBH & CO.,
KG
Uberlingen
DE
|
Family ID: |
38561685 |
Appl. No.: |
11/843918 |
Filed: |
August 23, 2007 |
Current U.S.
Class: |
342/14 |
Current CPC
Class: |
H04K 3/62 20130101; H04K
2203/24 20130101; H04K 3/44 20130101; H04K 3/42 20130101; F41H
11/02 20130101 |
Class at
Publication: |
342/14 |
International
Class: |
F41H 11/02 20060101
F41H011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 2, 2006 |
DE |
102006041225.7 |
Claims
1. A method for defense against surface-to-air missiles
(Manpads=Man Portable Air Defense Systems) which represent a threat
to military and civil aircraft during takeoff and landing, wherein
the missile is jammed by irradiating it with electromagnetic
jamming radiation.
2. A method according to claim 1, wherein the electromagnetic
jamming radiation utilizes microwave radiation or radio-frequency
radiation as the electromagnetic jamming radiation.
3. A method according to claim 1 or 2, wherein the electromagnetic
jamming radiation utilizes continuous-wave radiation.
4. A method according to claim 3, wherein the continuous-wave
irradiation uses a constant jamming radiation frequency.
5. A method according to claim 3, wherein the continuous-wave
irradiation is tuned over a predetermined jamming radiation
frequency range.
6. A method according to claim 1 or 2, wherein frequency packets
with a defined pulse repetition rate are used as the
electromagnetic jamming radiation.
7. A method according to claim 6, wherein there are utilized said
frequency packets with a specific constant injection frequency.
8. A method according to claim 6, wherein there are utilized said
frequency packets with injection frequencies that are varied in
steps.
9. A method according to claim 6, wherein there are utilized said
frequency packets with injection frequencies that are varied
continuously.
10. A method according to claim 1 or 2, wherein there are utilized
said frequency packets which differ from one another and have pulse
repetition rates that differ from one another as the
electromagnetic jamming radiation, with time windows, which are
governed by the pulse repetition rate of a first frequency packet,
being used for at least one second frequency packet.
11. A method according to claim 1 or 2, wherein there are utilized
parallel additive frequency packets with frequencies which differ
from one another as the electromagnetic jamming radiation.
12. A method according to claim 11, wherein there are utilized
frequency packets with different pulse repetition rates.
13. A system for defense against surface-to-air missiles
(Manpads=Man Portable Air Defense Systems) which represent a threat
to military and civil aircraft during takeoff and landing,
including an Arbitrary Waveform Generator (AWG) (12) and a number
of parallel-connected individual modules (14), which each have a
phase shifter (16), an amplifier (18) downstream of the phase
shifter, an antenna (20) downstream of the amplifier, and a phase
detector (22), which is associated with the phase shifter (16).
14. A system according to claim 13, wherein the individual modules
(14) are each connected in parallel with one another by a parallel
phase shifter (28).
15. A system according to claim 13, wherein the parallel-phase
shifters (28) are operatively connected to one another by a joint
phased array controller (30) which processes frequency information
from the AWG (12).
16. A system according to claim 13, wherein there are provided an
AWG (12) and a number of parallel-connected individual modules
(14), each having a pair of mutually parallel phase shifters (16),
a phase detector (22), which is associated with a respective said
phase shifter, an amplifier (18) downstream of the two phase
shifters (16), and an antenna (20) downstream of the amplifier,
with the respective phase shifter (16) and the therewith associated
phase detector (22) each having an associated bandpass filter
(24).
17. A system for defense against surface-to-air missiles
(Manpads=Man Portable Air Defense System) which represent a threat
to military and civil aircraft during takeoff and landing, wherein
there are provided a number of parallel-connected individual
modules (14), which each have an AWG (12) with an integrated,
multi-frequency phase shifter, an amplifier (18) downstream
therefrom, and an antenna (20) downstream of the amplifier (18),
with the AWGs (12) being synchronized via a master clock (26).
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and also to a
system, which provide for a defense against surface-to-air missiles
which represent a threat to military and civil aircraft during
takeoff and landing.
[0003] 2. Discussion of the Prior Art
[0004] Military and civil aircraft can be attacked by
surface-to-air missiles (Manpads=Man Portable Air Defense Systems)
during takeoff and landing. Manpads such as these are available
even to terrorist groups throughout the world and in consequence
represent an increasingly serious threat. These surface-to-air
missiles are generally of a relatively old type and at the moment
are generally still equipped with analogue electronics.
SUMMARY OF THE INVENTION
[0005] The invention is based on the object of providing a method
and a system of the type mentioned initially which, using simple
means, is suitable for defense against surface-to-air missiles
(=Manpads), which represent a threat to military and civil aircraft
during takeoff and landing.
[0006] With regard to the method, this object is achieved by a
jamming of the missile through irradiating it with jamming
radiation. Preferred embodiments and developments of the method
according to the invention are further characterized in the
dependent claims. The object on which the invention is based is
achieved, with regard to the system, by providing an Arbitrary
Waveform Generator (AWG) and a number of parallel-connected
individual modules, which each have a phase shifter, an amplifier
downstream of the phase shifter, an antenna downstream of the
amplifier, and a phase detector which is associated with the phase
shifter. Preferred embodiments and developments of the system
according to the invention are detailed in various dependent
claims. The object on which the invention is based can also be
achieved by the system, which provides for a number of
parallel-connected individual modules, which each have an AWG with
an integrated multi-frequency phase shifter, an amplifier
downstream therefrom, and an antenna downstream of the amplifier,
with the AWGs being synchronized via a master lock.
[0007] The applicants have derived interaction data for the
capability to influence various Manpads by irradiation with
electromagnetic jamming radiation. The Manpads investigated exhibit
different sensitivity profiles over the respectively injected
frequency of the electromagnetic jamming radiation. Jamming
voltages with different amplitudes are produced on the sensitive
signal lines of the analogue control electronics of the Manpads, as
a function of the frequency of the jamming radiation. In addition,
pronounced resonance effects occur. In this case, it has also been
found that the resonant frequencies vary to a certain extent as a
function of the angle of incidence of the radiation (AOI=angle of
incidence) of the jamming radiation on the surface-to-air
missile.
[0008] In addition, relatively old missiles with analogue control
electronics such as these also have internal operating frequencies.
If the jamming radiation that is suitable for ideal injection is
additionally modulated or clocked with a frequency which
corresponds to the appropriate operating frequency, then it is
probable that the homing head of the missile to be defended against
will lose the target.
[0009] A required pulse repetition frequency can also have
superimposed on it the frequency of a rolling movement of the
missile to be defended against.
[0010] The behaviour of the homing head and thus the trajectory of
the missile to be defended against can be simulated. Appropriate
simulation tools have been developed for various Manpads by the
applicants. This makes it possible to verify the effectiveness of
electromagnetic jamming irradiation with optimized parameters.
[0011] Pulsed irradiation with the ideal clock frequency results in
the field strength required for missile defense and attack rising
as the pulse duration becomes shorter, that is to say the field
strength is inversely dependent on the pulse duration. Optimization
is in consequence possible in terms of the respective minimum
required field strength and the shortest possible pulse length.
[0012] In addition to the dependency of the resonant frequencies on
the angle of incidence (AOI), the required field strengths and
pulse lengths differ for different missiles, in the same way as the
required clock frequencies.
[0013] A missile to be defended against or a plurality of--also
different--attacking missiles may, according to the invention, have
electromagnetic jamming radiation applied to it or them after
detection, by means of phase control which can be directed and
which it may be possible to slave. Slaving may comprise mechanical
or electronic slaving by means of phase control (beam
steering).
[0014] The electromagnetic jamming radiation may comprise
radio-frequency waves (RF) or microwaves (MW). The waveform emitted
from at least one jamming radiation source, in terms of its
frequency, pulse length, pulse amplitude, that is to say electrical
field strength, clocking etc., and its time profile, are such that
the operation of the at least one attacking missile is permanently
jammed, so that it can no longer carry out its mission.
[0015] According to the invention, a missile can be jammed and thus
defended against by means of continuous-wave irradiation (CW) at a
suitable frequency f. When a Manpad is irradiated with a known
frequency, which has previously been determined in laboratory
experiments and is ideal for the injection of jamming, the missile
can be deflected from its trajectory. In general, one advantage of
continuous-wave irradiation is that a relatively low field-strength
amplitude is required at the target. This allows very great ranges
to be achieved with a given transmission power and antenna
configuration. However, CW irradiation requires a relatively high
power level. Furthermore, one specific fixed frequency generally
allows only one specific missile to be defended against. This means
that it may possibly be necessary to identify the attacking
missile. Furthermore, the ideal injection frequency is generally
shifted for different irradiation angles, that is to say angles of
incidence (AOI), which may result in a reduction in the jamming or
defensive effect.
[0016] The jamming radiation frequency can be tuned over a
predetermined frequency range according to the invention, as well,
in order to compensate for any discrepancies from the optimum
jamming frequency which may, for example, be a result of
missile-specific and/or trajectory-specific constraints. This
involves somewhat more technological complexity and the need to
scan the frequency range within a relatively narrow time interval,
in order to ensure the appropriate effect at the missile to be
defended against. Another option according to the invention is to
use frequency packets at the frequency f, with a suitable defined
pulse repetition rate, as the electromagnetic jamming radiation.
This means that, as an alternative to the continuous-wave
irradiation of a missile to be defended against, as mentioned
above, it is also possible to irradiate the missile in a clocked
form with short pulses at the optimum injection frequency f.sub.1.
The field strength E.sub.1 at the target, that is to say at the
missile to be defended against, that is required to defend against
that missile generally increases with short pulses. In this case,
an optimum can be found at which the necessary field strength still
rises very little in comparison to CW irradiation in order to
achieve the same defensive effect. The clocking, that is to say the
repetition rate of the pulses, and the injection frequency, must be
chosen as appropriate for the missile to be defended against.
[0017] The jamming of, that is to say defense against, a missile by
irradiation with frequency packets at the frequency fi and with a
suitable pulse repetition rate has the advantage over CW
irradiation that it results in a reduced mean power requirement,
with appropriate optimization, for the same defensive effect. On
the other hand, a somewhat higher peak field strength is required
at the target, and a somewhat reduced range is possible when the
power limit of the radiation source is reached.
[0018] Continuous-wave irradiation, that is to say CW irradiation,
and the use of frequency packet irradiation for jamming the missile
do not overcome the relationship between the resonant frequencies
of the missile and the angle of incidence. Since the angle of
incidence cannot easily be determined, it is proposed, for example,
to emit different frequency packets immediately successively in
each pulse. These frequency packets are selected as appropriate
from previous injection experiments using different angles of
incidence, in order to obtain a good cross section for injection in
at least one case, that is to say for at least one frequency. This
means that, instead of having to use frequency packets at one
specific constant injection frequency, it may be advantageous to
use frequency packets with varying injection frequencies. These
changes to the injection frequencies may be in steps or
continuously. A so-called frequency sweep is therefore also
suitable, as an alternative to discrete frequencies. This frequency
sweep can also be chosen as appropriate on the basis of the
interaction data. The bandwidth and the sweep rate are kept
relatively narrow and low, respectively, in order to carry out
effective injection over an adequate irradiation time, with respect
to the width of the injection resonance. This is because, if the
sweep were too fast, the required field strength for jamming would
rise analogously to very short pulse durations. If a missile to be
defended against is irradiated with pulsed frequency packets, that
is to say pulse packets, which each comprise a frequency sweep,
this results in the advantage that, with an appropriate design, it
is not necessary to know the angle of incidence of the missile.
However, the mean power requirement increases.
[0019] According to the invention, it is also possible to use
frequency packets, which differ from one another and have pulse
repetition rates that differ from one another as the
electromagnetic jamming radiation, with the time windows, which are
governed by the pulse repetition rate of a first frequency packet,
being used for at least one-second frequency packet. This allows a
plurality of missiles, or different missiles, to be jammed by
time-division multiplexing of different missile-specific frequency
packets. If all the frequencies for one type of missile or for
groups of missiles are covered for different angles of incidence
(AOI), then pulsing at a first pulse repetition rate results in
time gaps which can be used for further missiles. These time gaps
are filled with at least one further frequency packet. The number
of different missiles to be attacked using different parameters is
in this case limited only by the maximum time window that is
available for attack purposes. This method variant has the
advantage that a plurality of missile types can be attacked,
without any need to identify the different missile types. This
method according to the invention requires a high mean power level,
however; maximum utilization of the time gaps results in a power
requirement which corresponds approximately to the power
requirement for continuous-wave irradiation, that has been
described further above.
[0020] According to the invention, it is also possible to use
parallel additive frequency packets with frequencies which differ
from one another as the electromagnetic jamming radiation. This
allows a plurality of missiles, or different missiles, to be jammed
by parallel additive emission of a plurality of different
missile-specific frequency packets. This is because, in a similar
manner to the method according to the invention described first of
all, it is also possible to emit the determined frequency packets,
in an optimally specific form for the missile, in parallel and
additively. This has the advantage that it avoids any restriction
to time gaps or to the available time window. In principle, any
desired number of different missiles can therefore be irradiated.
In this case, additive frequency mixing can be used to attack a
plurality of missile groups at the same time. The power required by
an amplifier increases in this case, of course, since the maximum
amplitude, that is to say the field strength, may be two or more
times the two individual amplitudes or plurality of individual
amplitudes. However, this procedure has the advantages that a
plurality of missile types can be attacked, without any need to
identify the different missile types. A further advantage is that
there is no restriction to the number of frequency patterns
resulting from the subdivision of time gaps.
[0021] The system according to the invention for carrying out the
method according to the invention may be characterized in that an
Arbitrary Waveform Generator (AWG) and a number of
parallel-connected individual modules are provided, which each have
a phase shifter, an amplifier downstream from the phase shifter, an
antenna downstream from the amplifier, and a phase detector
associated with the phase shifter. It is therefore possible to emit
high-power electromagnetic waves which, by means of suitable
emitted signal forms, cause missions of one or more missiles to be
rendered ineffective at the same time, by jamming its or their
control and steering circuit electronics. Since the individual
amplifier systems have a restricted maximum power, addition of a
plurality of amplifier systems in the correct phase is desirable
according to the invention. The amplifiers and the antennas in the
individual modules normally have a frequency-dependent and
amplitude-dependent phase shift between the input and the output,
which can also vary between the respective amplifiers in the
individual modules. If amplifier-antenna systems are cascaded in
order to influence Manpads, it is, however, necessary to ensure
phase synchronization at the respective antenna outputs. Phase
control is therefore provided between the respective amplifier
input and the antenna.
[0022] Connecting the individual modules in parallel allows more
power to be emitted, and a higher gain. The necessary phase
synchronicity is achieved by a phase detector/phase shifter
structure, which regulates the phase between the antenna output
signal and the AWG output to be the same. For this purpose,
appropriate signals can be tapped off directly from the antenna or
from the respectively associated amplifier.
[0023] Different frequency bursts are emitted sequentially in the
AWG, in time with the critical pulse repetition rate. This allows
adaptation of the direction-dependent frequency selectivity of the
target, that is to say Manpad. The limit to the pulse repetition
rate, the pulse length and the number of frequencies is defined by
the finite time window mentioned above.
[0024] This system according to the invention has the advantage
that only a single AWG--or DDS synchronizer--is required. The
individual modules, with feedback, guarantee that the phases are
the same, thus advantageously allowing simple parallel connection
and coupling to the AWG.
[0025] If an electrically controlled directional effect is desired,
this can be achieved by additional phase shifters, that is to say
delay elements, downstream from the AWG.
[0026] The need for sequential arrangement of the sine-wave
functions in the AWG is based on the fact that the phase detector
and phase shifter mentioned above are effective for only one
sine/time function. An extension to the system is based on
frequency separation of the antenna measurement signal and of the
AWG signal by means of bandpass filters. In this case, phase
detection and correction at the phase shifter are carried out for
each frequency that is filtered out in this way. This also allows
simultaneous addition of the frequencies to be emitted, without any
restriction resulting from the maximum available time window.
[0027] The system according to the invention can also be
implemented in such a way that a number of parallel-connected
individual modules are provided, which each have an AWG with an
integrated, multi-frequency phase shifter, an amplifier downstream
from it and an antenna downstream from the amplifier, with the AWGs
being synchronized via a master clock. If the system according to
the invention is designed in this way, the amplifiers and antenna
system likewise have a frequency-dependent and amplitude-dependent
phase shift between the input and the output. This phase shift can
also vary between the amplifiers. When amplifier-antenna systems
are cascaded in order to influence Manpads, the phases at each of
the antenna outputs must, however, be the same. Phase control, that
is to say phase correction, is for this purpose provided in a
digital form between an absolute reference phase for all of the
AWGs and the respective antenna output, in the AWG.
[0028] Connecting the individual modules in parallel allows more
power to be emitted and a higher gain. The necessary phase
synchronicity is achieved by a multi-frequency phase adaptation in
completely digital form, controlling the phase between the antenna
output signal and the internal AWG frequency to be the same for all
of the frequencies which are emitted at the same time. In this
case, all of the AWGs are synchronized via a master clock.
Frequency bursts at different frequencies are added in the AWG, and
are emitted in time with the critical pulse repetition rate. This
allows adaptation of the direction-dependent frequency selectivity
of the target, while allowing different targets to be attacked at
the same time. The only limit to the number of different
frequencies is the maximum amplifier output power.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Further details, features and advantages of the invention
will be evident from the following description of the figures, in
which:
[0030] FIG. 1 shows an energy-time diagram for continuous-wave
irradiation;
[0031] FIG. 2 shows an energy-time diagram for irradiation of a
missile with energy pulses;
[0032] FIG. 3 shows an energy-time diagram of irradiation with
pulsed energy packets, which are each composed of different
discrete frequencies;
[0033] FIG. 4 shows an energy-time diagram for irradiation with
pulsed energy packets, which each comprise a frequency sweep;
[0034] FIG. 5 shows an energy-time diagram in order to illustrate
sequential irradiation with parameters, whose frequency and pulse
repetition rate are matched, for different missiles or missile
groups;
[0035] FIG. 6 shows an energy-time diagram in order to illustrate
irradiation with parameters, whose frequency and pulse repetition
rate are matched, for different missiles or missile groups in the
parallel additive mode;
[0036] FIG. 7 shows one embodiment of the system according to the
invention with an AWG;
[0037] FIG. 8 shows an extension to the implementation capability
of the system as shown in FIG. 7, illustrating only one individual
module; and
[0038] FIG. 9 shows another embodiment of the system according to
the invention, with individual modules, which each have an AWG,
connected in parallel.
DETAILED DESCRIPTION OF THE INVENTION
[0039] FIG. 1 shows an energy-time diagram of continuous-wave
irradiation of a Manpad at a frequency f.sub.1, which is ideal for
one specific missile to be defended against, and with the energy
E.sub.0. When a missile to be defended against is irradiated at a
known frequency f.sub.1, which has been determined in advance in
laboratory experiments and is ideal for the injection of jamming,
the missile can be deflected from its trajectory. Continuous-wave
irradiation such as this generally requires the lowest
field-strength amplitude E.sub.0 at the target. This allows the
maximum ranges to be achieved for a given transmission power and
antenna configuration.
[0040] FIG. 2 shows an energy-time diagram of the jamming of a
missile to be defended against by irradiation with frequency
packets at the frequency f.sub.1 and with a suitable pulse
repetition rate .DELTA.t. In this case, .DELTA.t=1/f.sub.PPR, where
f.sub.PRR is the respective pulsing, which is chosen on a
missile-specific basis, in the same way as the injection frequency
f.sub.1. The field strength E.sub.1 at the target required for
defense against a missile generally increases as the pulses become
shorter; however, an optimum can be found at which the required
field strength E.sub.1 still rises very little in comparison to the
field strength E.sub.0 for continuous-wave irradiation (see FIG.
1), in order to achieve the same effect.
[0041] The continuous-wave irradiation as shown in FIG. 1 and
jamming of the missile by irradiation with frequency packets at the
frequency f.sub.1 and with a suitable pulse repetition rate
.DELTA.t does not overcome the dependency of the resonant
frequencies of the respective missile on the angle of incidence.
Since the angle of incidence cannot be determined easily, it is
possible, for example, to emit different frequency packets
immediately successively in each clock cycle .DELTA.t. These
frequency packets are chosen appropriately from previous injection
experiments using different angles of incidence, in order to obtain
a good cross section for injection in at least one case--for at
least one frequency. This is illustrated in FIG. 3, which shows an
energy-time diagram for irradiation with pulsed packets, which are
each composed of different, successive, discrete frequencies
f.sub.1-, f.sub.1, f.sub.1+. The pulse repetition rate .DELTA.t is
the same as that shown in FIG. 2.
[0042] FIG. 4 shows an energy-time diagram of the irradiation of a
missile to be defended against with pulsed packets which each
comprise a frequency sweep f.sub.1- . . . f.sub.1+. This means that
a frequency sweep, that is to say continuous frequency variation,
is possible as an alternative to switched discrete frequencies
f.sub.1-, f.sub.1, f.sub.1+. This frequency sweep is chosen
appropriately, on the basis of the corresponding interaction
data.
[0043] FIG. 5 shows an energy-time diagram for sequential
irradiation with parameters, whose frequency and pulse repetition
rate are matched, for different missiles or missile groups to be
defended against. If all of the frequencies for one type of
missile--or missile group--are covered for different irradiation
angles (AOI), then pulsing at a specific pulse repetition rate
.DELTA.t.sub.1 results in time gaps in the corresponding time
period, and these can be used for further missiles. These time gaps
between the frequency packets f.sub.1-, f.sub.1, f.sub.1+ are
filled with further frequency packets f.sub.2. The number of
missiles which can be attacked with different parameters is limited
only by the said maximum time window that is available for attack
purposes.
[0044] The pulse repetition rate .DELTA.t.sub.2 of the frequency
packets f.sub.2 is governed by the pulse repetition rate
.DELTA.t.sub.1.
[0045] FIG. 6 shows irradiation with parameters, whose frequency
and pulse repetition rate are matched, for different missiles or
missile groups in the parallel-additive mode. This avoids a
restriction to gaps in the time period, that is to say to an
available time window. In principle, any desired number of
different missiles can be irradiated, in order to defend against
them. FIG. 6 shows an exemplary embodiment for two missile groups,
for which the necessary frequency packets f.sub.1 and f.sub.2
overlap in time. Nevertheless, additive frequency mixing allows
both missile groups to be attacked at the same time.
[0046] FIG. 7 illustrates a system 10 according to the invention
for defense against surface-to-air missiles (Manpads) which
represent a threat to military and civil aircraft during takeoff
and landing. The system 10 has an Arbitrary Waveform Generator
(AWG) 12 and a number of parallel-connected individual modules 14.
Each individual module 14 has a phase shifter 16, an amplifier 18
downstream from the phase shifter 16, and an antenna 20 downstream
from the amplifier 18. Each phase shifter 16 has an associated
phase detector 22. This allows a corresponding number of amplifier
systems to be added in the correct phase, since the individual
amplifier systems each have a limited maximum power. The amplifiers
18 and the antennas 20 normally have a frequency-dependent and
amplitude-dependent phase shift between the input and the output,
and this phase shift may also vary between the individual
amplifiers 18. However, if amplifier-antenna systems are cascaded
in order to influence Manpads, that is to say to defend against
them, it is necessary to ensure phase synchronization at each of
the antenna outputs. Phase control is carried out for this purpose
between the respective amplifier input and the antenna 20.
[0047] Connecting the individual modules 14 in parallel allows more
power to be emitted, and a higher antenna gain. The required phase
synchronicity is achieved by the phase detector/phase shifter
structure which controls the phase between the antenna output
signal and the output of the AWG 12 to be the same. For this
purpose, the appropriate signals can be tapped off, for example,
directly from the respective antenna 20--or from the corresponding
amplifier 18.
[0048] Different frequency bursts are emitted sequentially in time
with the critical pulse repetition rate .DELTA.t in the AWG 12.
This allows adaptation of the direction-dependent frequency
selectivity of a Manpad.
[0049] The system 10 shown in FIG. 7 requires only a single AWG
12--or DDS synthesizer.
[0050] The individual modules 14 are each connected in parallel
with one another, by means of a parallel phase shifter 28. The
parallel phase shifters 28 are operatively connected to one another
by means of a joint phased array controller 30, which processes
frequency information from the AWG 12.
[0051] FIG. 8 illustrates an extension to the system shown in FIG.
7. In this embodiment, an AWG 12 and a number of parallel-connected
individual modules 14 are provided, only one of which is shown in
FIG. 8. Each individual module 14 has a pair of phase shifters 16
in parallel with one another, a phase detector 22 associated with
the respective phase shifter 16, an amplifier 18 downstream from
the two phase shifters 16 and an antenna 20 downstream from the
amplifier 18. Each of the phase shifters 16 and the respectively
associated phase detector 22 have an associated bandpass filter
24.
[0052] The need for sequential arrangement of the sine-wave
functions in the AWG 12 is based on the fact that the phase
detector 22 and the phase shifter 16 are effected for only one
sine-time function. The extension to the system shown in FIG. 8 is
based on frequency separation of the antenna measurement signal and
the AWG signal by means of bandpass filters 24, with only the phase
detection and correction at the phase shifter 16 being carried out
for each frequency which is filtered out in this way. This allows
simultaneous addition of the frequencies to be emitted, and avoids
any restriction to the maximum available time window. This covers
the application illustrated in FIG. 6.
[0053] FIG. 9 shows an embodiment of the system 10 in which a
number of parallel-connected individual modules 14 are provided and
each have an AWG 12 with an integrated multi-frequency phase
shifter, an amplifier 18 downstream from the respective AWG 12, and
an antenna 20 downstream from the respective amplifier 18, with the
AWGs 12 being synchronized via a master clock 26.
[0054] Connecting the individual modules 14 in parallel as shown in
FIG. 9 allows more power to be emitted and a correspondingly higher
antenna gain. The required phase synchronicity is achieved by
multi-frequency phase adaptation provided in an entirely digital
form, which controls the phase, for all of the frequencies emitted
at the same time, between the output signal of the respective
antenna 20 and the internal AWG frequency, to be the same.
Frequency bursts at different frequencies are added in the AWG 12
and are emitted in time with the critical pulse repetition rate
.DELTA.t. This allows adaptation of the direction-dependent
frequency selectivity of the missile to be defended against, while
allowing different targets, that is to say missiles, to be attacked
at the same time.
LIST OF REFERENCE SYMBOLS
[0055] 10 System [0056] 12 AWG/Arbitrary Waveform Generator (of 10)
[0057] 14 Individual module (of 10) [0058] 16 Phase shifter (of 14)
[0059] 18 Amplifier (of 14) [0060] 20 Antenna (of 14) [0061] 22
Phase detector (for 16) [0062] 24 Bandpass filter (of 14) [0063] 26
Master clock (of 10) [0064] 28 Parallel phase shifter [0065] 30
Phased array controller
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