EP2546928B1 - Antenna assembly for emitting microwave pulses - Google Patents

Description

The present invention relates to an antenna arrangement for emitting microwave pulses of high energy.

Microwave pulses high energy density, especially those based on the HPEM (High Power Electromagnetics) technology are nowadays used to electronic components threatening objects, such as those of time-triggered or mobile phone-controlled explosives such. B. booby traps or the like. To destroy or at least dysfunctional. Corresponding microwave pulse generating systems are preferably used in the form of portable systems or carried on vehicles. They should therefore be as compact as possible. The possibility of using such systems is not limited to the near field, but can be extended to larger ranges, for example, with the aim of impairing the trajectory of electronically controlled objects such. B. missiles or the like. One strives for the applications described to produce pulses with the highest possible energy density and power. However, HPEM sources have the disadvantage that the switching process is dependent on a sparkover. This in turn results in the disadvantage that the time of radiation is not reproducible with sufficient accuracy. The structure of the source array is therefore difficult. In addition, HPEM sources are subject to an increased mechanical stress due to the aforementioned switching operation and therefore have a comparatively limited life. In addition, it is necessary for HPEM sources to provide an excitation signal with the shortest possible rise time, which is subject to a device limitation.

From the US 3,748,528 For example, a microwave pulse generator is known in which a pulse with a rise in the order of a nanosecond and an amplitude in the range of 12-20 kV is generated at a first spark gap. This pulse is subsequently converted into a damped sinusoidal oscillation (DS pulse) via another series-connected spark gap, which functions as a switch, and emitted via a reflector or an antenna.

From the WO 98/36490 , of the US 5,774,091 and the US 2005/0285447 A1 Microwave generators are known. The post-published EP 2 397 809 A2 describes an arrangement for generating microwave pulses of high energy.

In order to increase the energy density of such impulses one has additionally gone over, as in the DE 10 2006 014 230 A1 or in the DE 103 13 286 B3 is shown to provide arrangements of a plurality of parallel-connected microwave generators. However, such arrangements have the disadvantage that they require a certain amount of space and are therefore only of limited suitability for arrangements with reduced dimensions.

The object of the present invention is to provide a novel antenna arrangement which allows to emit pulse-shaped signals with improved properties.

The above object is achieved by an antenna arrangement according to claim 1. Advantageous embodiments of the invention are specified in the dependent claims. Among other things, a first planar electrode and a second planar electrode are provided, wherein the first electrode and the second electrode are connectable to a generator for generating an excitation pulse, further comprising a plurality of non-linear radiation elements, which connect the first and the second electrode together and Semiconductor diodes, which are provided in the region of the non-linear radiation elements and turn on from a certain breakdown voltage and thereby a pulse-shaped total pulse can be emitted by the antenna. The novel antenna arrangement ensures a high reproducibility of the emitted pulse-shaped signals (pulses) as well as the emission time, since the switching process is not based on a spark gap but on a semiconductor, namely on the semiconductor diode. This in turn results in significantly lower losses and a significantly longer service life. Furthermore, the novel antenna arrangement allows the use slower pulse generators, at the same time the emission of pulsed signals with higher frequencies (> 300 MHz) than before (maximum 50 MHz) can be achieved. Thus, for example, the emission of pulsed signals with frequencies> 300 MHz can be carried out with excitation with slow rise times of about 10 ns.

Expediently, the first planar electrode and the second planar electrode are conductive plates, preferably metal plates, so that the antenna arrangement forms a plate capacitor in which a multiplicity of radiation elements distributed over the surface of the plates are in the form of dipoles.

The supply line in the form of a plate capacitor as part of the antenna arrangement allows a three-dimensional arrangement of the radiation elements depending on the desired application. In particular, this also increases the radiated field. Depending on the location of the supply line, the emission direction of the antenna device can be influenced.

The radiation elements according to the invention comprise two elongate conductive elements, for. B metal strips which communicate with each other via the semiconductor diode.

The fact that the feeding of the radiation elements takes place at the respective electrode via inductors, the efficiency of the antenna assembly is increased in particular.

Expediently, the semiconductor diodes accommodated in the radiation elements have a so-called "avalanche breakdown characteristic". These are semiconductor diodes with very fast decay times. A voltage is applied to the diodes via the supply line and the two inductors. From a certain breakdown voltage, the diodes switch through and a pulse-shaped signal is emitted. The radiated frequency is independent of the rise time of the excitation signal. For this reason, one does not need a generator with fast rise time in the novel antenna arrangement. Nevertheless, switching times in the range of less than 500 ps can be achieved.

The antenna arrangement according to the invention ensures great freedom in terms of its application and its use. For example, between the flat electrodes or plates, multiple radiation sources in series be arranged one behind the other in each case, so that for example in the case of two radiation elements, the distance between the electrodes or plates is about twice as long as the dipole length of each radiation element.

Alternatively, a distance may be provided which is smaller than the length of the respective radiation element or as the dipole length. In this case, apertures are arranged in the electrodes through which the radiation elements protrude. The distance between the two electrodes or plates is smaller than the length of the radiation element, d. H. the dipole length. By changing the distance, the capacitance changes, so that adaptation of the energy of the generator to the antenna arrangement can take place by adjusting the distance.

With the novel antenna arrangement, it is possible with comparatively slow generators to generate a radiated pulse-shaped signal with a high frequency, for example with frequencies of> 200 MHz, preferably> 250 MHz, particularly preferably> 300 MHz.

The rise times of the excitation signal of the generator may preferably be ≥ 1 ns, particularly preferably ≥ 5 ns.

To increase the effectiveness of the radiated pulse-shaped signal, the antenna arrangement according to the invention can be combined in a simple manner with at least one passive reflector.

Depending on the intended use, a reflector can be arranged laterally to the arrangement of the plurality of individual radiation elements and electrodes, whereby a targeted direction of propagation of the pulse-shaped signal, ie an optimization of the signal in the desired direction.

Alternatively, a reflector can enforce the arrangement of the individual radiation elements and the electrodes or plates, so that a propagation direction of the pulse-shaped signal in z. B. results in two directions.

If an all-round propagation direction is intended, a plurality of reflectors can also be provided. For example, a reflector cross may be formed, in which the individual radiation elements are arranged substantially concentrically around the point of intersection of the reflectors.

Advantageous embodiments of the present invention are explained below with reference to drawing figures. Repetitive features are provided for clarity only once with the relevant reference numerals.

Fig. 1

eine vereinfachte Darstellung der Impulsform eines von einem Impulsgenerator direkt erzeugten Impulses,

Fig. 2

eine vereinfachte Darstellung einer ersten Ausgestaltung der erfindungsgemäßen Antennenanordnung in perspektivischer Ansicht,

Fig. 3

eine Darstellung einer weiteren Ausführungsform der erfindungsgemäßen Antennenanordnung in perspektivischer Ansicht,

Fig. 4

eine weitere Ausgestaltung der erfindungsgemäßen Antennenanordnung in perspektivischer Ansicht,

Fig. 5

eine Darstellung der erfindungsgemäßen Antennenanordnung unter Verwendung eines seitlich angeordneten passiven Reflektors in Seitenansicht des Reflektors (Fig. 5A) sowie Draufsicht auf den Reflektor (Fig. 5B),

Fig. 6

eine Darstellung der erfindungsgemäßen Antennenanordnung mit einem die Antennenanordnung durchsetzenden passiven Reflektor für eine beidseitige Abstrahlung in Seitenansicht des Reflektors (Fig. 6A) sowie Draufsicht auf den Reflektor (Fig. 6B) sowie

Fig. 7

eine Darstellung der erfindungsgemäßen Antennenanordnung unter Verwendung zweier sich kreuzender Reflektoren für eine allseitige Abstrahlung in Seitenansicht des einen Reflektors (Fig. 7A) sowie in einer Draufsicht auf die Oberseite der Anordnung gemäß Fig. 7A unter Weglassung der oberen Elektrode (Fig. 7B).

Show it:

Fig. 1

a simplified representation of the pulse shape of a pulse directly generated by a pulse generator,

Fig. 2

a simplified representation of a first embodiment of the antenna arrangement according to the invention in a perspective view,

Fig. 3

a representation of another embodiment of the antenna arrangement according to the invention in a perspective view,

Fig. 4

a further embodiment of the antenna arrangement according to the invention in a perspective view,

Fig. 5

1 is a representation of the antenna arrangement according to the invention using a laterally arranged passive reflector in a side view of the reflector (FIG. Fig. 5A ) and top view of the reflector ( Fig. 5B )

Fig. 6

4 shows an illustration of the antenna arrangement according to the invention with a passive reflector passing through the antenna arrangement for a radiation on both sides in a side view of the reflector ( Fig. 6A ) and top view of the reflector ( Fig. 6B ) such as

Fig. 7

a representation of the antenna arrangement according to the invention using two crossing reflectors for an all-round radiation in side view of a reflector ( Fig. 7A ) and in a plan view of the top of the arrangement according to Fig. 7A omitting the upper electrode ( Fig. 7B ).

The Fig. 1 shows the shape of a typical excitation signal of a generator. The excitation signal has a short rise time in the nanosecond range, for example, a rise time of 10 ns, until the signal reaches its peak. The amplitude is on the order of usually about 150-200 kV. The frequency of such a pulse-shaped signal is in the MHz range. The higher the frequency, the higher the energy of the pulse-shaped signal. Usually, the higher the rise time of the excitation signal, the higher the frequency of the signal to be radiated.

Fig. 2 shows a highly simplified schematic representation of a first embodiment of the antenna arrangement 2 according to the invention. The antenna arrangement 2 comprises a first planar electrode 3 and a second planar electrode 4, for example in the form of planar conductive plates, for. B. metal plates, which are arranged at a certain distance from each other and form a plate capacitor. Each electrode 3, 4 has a feed point 11 or 12 for feeding the pulse-shaped signal from a generator 1, in this case approximately in the middle of the left side edge of the electrode 3 or 4. The generator 1 may be a generator with a comparatively "small" rise time, for example, of> 1 ns.

Between the two electrodes 3, 4 are a plurality of parallel, dipole-like non-linear radiation elements 5, which connect the two electrodes 3, 4 with each other. A pulse-shaped signal fed in via the feed points 11, 12 is fed into all the radiation elements 5.

The radiation elements are elongated, conductive elements, for example metal strips made of Cu or Al, which are in each case connected to one another via a semiconductor diode 6. The input of the pulse-shaped signal from the generator 1 via the respective electrode 3, 4 in the respective radiation element 5 via inductors 7 and 8. The use of the inductors 7, 8 improves the emission time of the radiated from the antenna device 2 pulse and allows the increase of the pulse sharpness while increasing the pulse intensity.

The semiconductor diode 6 is expediently a semiconductor diode with a so-called avalanche breakdown characteristic, that is to say a semiconductor diode which is installed in the reverse direction with a fast fall time. Via the supply line and the two inductances 7, 8, a voltage is applied to the respective semiconductor diode 6. From a certain breakdown voltage, the semiconductor diode turns on and a pulse-shaped signal is radiated from the respective radiating element 5. The sum of the individual signals of the radiation elements 5 generated at the same time gives the total impulse emitted by the antenna arrangement. This is when the one-sided feed of Fig. 1 emitted in the direction of A.

Normally, the radiated frequency f depends on the rise time t as follows: $$\mathrm{f}<\mathrm{1}/\left(\mathrm{2}\times \mathrm{t}\right)$$

Due to the special feed of the antenna arrangement and the switching operation by the semiconductor diode can be advantageously dispensed with a generator with fast rise time. Because the radiated frequency is in this case independent of the rise time of the excitation signal. In addition, the antenna arrangement allows the use of slow pulse generators with a rise time of about 10 ns for the emission of pulsed signals with high frequencies of over 200 MHz, preferably of over 250 MHz, more preferably of over 300 MHz.

The radiation elements 5 represent dipoles. The number and arrangement in the antenna arrangement depends on the specific application. Likewise, the distance between the electrodes 3, 4, d. H. the plates, can be changed arbitrarily, depending on the application, impedance matching and radiation characteristics.

Out Fig. 3 shows a further embodiment of the antenna arrangement according to the invention can be seen in which the distance between the electrodes 3, 4 in comparison to the dipole length, ie the length of the individual radiation element, is increased. This is done by a plurality of radiation elements 5a, 5b connected in series are located between the electrodes 3, 4. The feeding of the excitation signal also takes place on both sides of the radiation element 5a, 5b provided inductances 7a, 7b and 8a, 8b. In the case of the embodiment according to Fig. 3 two radiating elements 5a and 5b are connected in series. However, even more radiation elements can be connected in series. This antenna arrangement radiates due to the lateral feed of the excitation signal from the generator 1 to the two electrodes 3, 4 in the direction A.

Depending on the application, it is also possible to provide the distance between the electrodes 3, 4 smaller than the dipole length or length of the radiation element 5 ( Fig. 4 ).

Here, openings 13 and 14 are provided in the respective electrodes 3, 4, so that the radiation elements 5 pass through the electrodes 3 and 4, respectively. The feeding of the excitation signal is also effected here via inductors 7 and 8, which contact the electrodes 3, 4 in the region of the openings 13, 14 and contact the radiation element 5 on the radiation element 5 on both sides of the semiconductor diode 6. By changing the distance, the capacitance of the plate capacitor changes, so that by adjusting the distance, an adaptation of the energy of the generator can be made to the antenna arrangement. The emission direction is indicated by the arrow A.

The arrangement according to the invention can also be combined with a passive reflector 10 in order to influence the emission, ie propagation direction A of the pulse to be generated. In the embodiment according to Fig. 5 the reflector 10 is laterally to the arrangement of the individual radiation elements 5, so that a propagation direction of the generated pulse in the direction A according to Fig. 5A results. As it turned out Fig. 5B results, the reflector 10, the arrangement of the individual radiation elements 5 completely covers.

In order to allow the propagation of the pulse to be radiated in two directions, according to Fig. 6 the passive reflector also enforce the arrangement of the individual radiation elements 5 and electrodes 3, 4. As a result, the radiated pulse propagates in both the direction A and the direction B, as shown Fig. 6A obviously, off.

Again, the reflector 10, as out Fig. 6B can be seen, the entire arrangement of the individual radiation elements 5 from.

Finally is off Fig. 7 an arrangement can be seen in which the pulse to be radiated by the antenna arrangement is to be transmitted on all sides. For this purpose, two reflectors 10, 11 are arranged crosswise to each other, wherein the individual radiation elements 5 in different rows concentrically around the crossing point of the reflectors 10, 11 are running around. This is especially good from the Fig. 7B in which, for the sake of clarity, the upper electrode 3 is not shown, can be seen. The respective electrode 3 or 4 is divided into two electrodes 3a, 3b and 4a, 4b. Each of the electrodes 3a and 3b or 4a and 4b becomes, as in FIG Fig. 7A represented, acted upon directly by the generator 1.

The new antenna arrangement makes it possible to emit microwave pulses with very high energy density and sharpness without having to use excitation signals with a very high rise time. Due to the good reproducibility of the switching time, arrays of individual radiation elements can be produced in any desired arrangement and size.

LIST OF REFERENCE NUMBERS

1

generator

2

antenna array

3

electrode

4

electrode

5

radiating element

6

Semiconductor diode

7

inductance

8th

inductance

9

reflector

10

reflector

11

entry point

12

entry point

13

breakthrough

14

breakthrough

Claims (13)

1. Antenna arrangement (2) for emitting high-energy microwave pulses, which antenna arrangement has a first flat electrode (3) and
   a second flat electrode (4),
   the electrodes (3,4) being able to be connected to a generator (1) for producing an excitation pulse, the electrodes (3,4) having feed points (11,12) for feeding the excitation pulse from the generator (1),
   characterized in that
   a multiplicity of radiation elements (5) are provided, which radiation elements connect the electrodes (3,4) to one another in such a manner that an excitation pulse is fed into all radiation elements (5) at the feed point (11,12),
   the radiation elements (5) each having two conductive elements which are connected to one another by means of a semiconductor diode (6),
   the semiconductor diodes (6) which are provided in the region of the radiation elements (5) being set up to turn on as of a particular breakdown voltage, thus making it possible for the antenna arrangement (2) to emit a pulsed overall pulse.
2. Antenna arrangement according to Claim 1,
   the first electrode (3) and the second electrode (4) being conductive plates.
3. Antenna arrangement according to Claim 1 or 2,
   the radiation elements (5) being fed by the respective electrode (3 or 4) via inductances (7, 8) .
4. Antenna arrangement according to one of the preceding claims,
   the semiconductor diode (6) having an avalanche breakdown characteristic.
5. Antenna arrangement according to one of the preceding claims,
   at least two radiation elements (5a, 5b) being arranged behind one another.
6. Antenna arrangement according to one of the preceding claims,
   the distance between the two electrodes (3, 4) being shorter than the length of the radiation elements (5).
7. Antenna arrangement according to one of the preceding claims,
   the frequency of the emitted overall pulse from the antenna arrangement being independent of the rise time of the excitation signal of the antenna arrangement.
8. Antenna arrangement according to one of the preceding claims;
   the emitted pulsed signal having a frequency of >200 MHz, preferably a frequency of >250 MHz, particularly preferably a frequency of >300 MHz.
9. Antenna arrangement according to one of the preceding claims,
   the rise time of the excitation signal being ≥1 ns, preferably ≥5 ns.
10. Antenna arrangement according to one of the preceding claims,
    the antenna arrangement (1) comprising at least one passive reflector (9 and/or 10).
11. Antenna arrangement according to Claim 10,
    the reflector (9 and/or 10) being arranged to the side of the arrangement of the radiation elements (5) .
12. Antenna arrangement according to Claim 10,
    the reflector (9 and/or 10) passing through the arrangement of the radiation elements (5).
13. Antenna arrangement according to Claim 12,
    at least two crossing reflectors (9, 10) being provided, and the individual radiation elements (5) being arranged in such a manner that they run substantially concentrically with respect to the crossing point of the reflectors (9, 10).

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