DE811967C - Pulse generator - Google Patents

Description

The invention relates to pulse generators and transmitters and, more particularly, to generators for Keying or modulation of ultra-short-wave radio transmitters for the transmission of periodically recurring, short pulses of high power.

Different systems, e.g. B. use distance measurement and object location systems periodically recurring impulses of high power on ultra-short radio waves. Such impulses can be of very short duration compared to the intervals between the pulses, e.g. B. the pulse frequency can be of the order of iooo to 4000 per second, while the Pulse length is on the order of a microsecond. As a result, the average power output and accordingly the average power required by the feed energy source very low, even with high power output peaks. On the other hand, the system must be able to be able to meet the high instantaneous power requirements during the pulse time.

An object of the invention is to improve the economy of the device and the mode of operation of the pulse generator.

Another object of the invention is to achieve periodically recurring, short pulses of high energy without a comparable instantaneous load on the mains connection.

Another object of the invention is the supply of energy to an ultra-high frequency vibration generator with periodically recurring, short pulses of high voltage

Direct current drawn from a low-voltage direct current source.

According to a characteristic of the present invention, periodically recurring high-voltage pulses are used high power, which trigger an ultra-high radio oscillation, from a low-voltage DC power source formed by taking energy from the power source electromagnetically and electrostatically in the period between pulses stores. More specifically, one is drawn from the power source by an induction coil flowing current interrupted so that a high-voltage charge builds up in a capacitance, which in turn is enabled to energize the oscillator for the required pulse period.

These and other objects, features, and aspects of the invention are intended to be referred to by reference to the following detailed ao description in connection with the drawings be brought to a better understanding.

Fig. Ι shows a basic circuit diagram of an embodiment the invention;

Figures 2, 3 and 4 are graphs ^{illustrating the a} 5 voltage and current relationships in the circuit of Figure 1;

FIG. 5 shows a basic circuit diagram of a modification of FIG. 1;

Fig. 6 is a graph of the current in one branch of the circuit of Figs. 5, and

Fig. 7 shows a basic circuit diagram of another circuit arrangement that replaces the circuit parts 1 or 5 to the right of the dash-dotted line X-X can be used.

In the system of FIG. 1, the invention is used to generate periodically recurring, short ones Pulses from high-power, ultra-high frequency radio waves. The ultra-high frequency vibrations are generated by a multi-slot magnetron 11, the anode 12 of which has an outer shield or a Forms housing that is expediently kept at ground potential. If the tube is a magnetic Is exposed to the field supplied by the magnet 13 and when a high DC voltage between ♦ 5 is applied to the anode and the cathode, high-power oscillations of a frequency are generated, which is determined by the internal structure of the arrangement. These vibrations can go through a loop 14 are included and via a coaxial line 15 to an antenna or a be transferred to another suitable useful circle, not shown. "

As already explained in the introduction to the description, the generator should be triggered in such a way that that periodically recurring high-power pulses of short duration are generated. As a result of the - The ratio of the pulse duration to the duration of the key pause can be achieved by the generator with peak power work that is well above the safety limit for continuous operation. This of course requires high instantaneous feed rates, and in the interest of the economy of both the operation as well as the device, it is desirable that it be generated from a primary power source which has a comparatively lower continuous output and no such peak loads having.

In the system of FIG. 1, the primary source is one Battery 17, although of course it is also a rectifier, generator or other direct current source can be. An induction or choke coil 18 is connected to the positive pole of the battery 17 tied together. During the rest or non-work part the operating period, a current flows from the battery 17 through the coil 18 and the open Vacuum tube 19. When this current has reached a sufficient value so that the required Energy is stored in the magnetic field of the coil, the flow of current is blocked by the tube 19 interrupted. However, the current tends to continue flowing in the same direction, so that the capacitor 20 is charged, the in the magnetic field of the coil 18 stored energy is transferred to the electrostatic field of the capacitor 20.

In the absence of other means of control, the current and the energy would then be reversed be fed back to the coil, the working cycle continues in the well-known way of an oscillating circuit until the energy through the resistor state of the circle is consumed.

In the arrangement shown, however, it is approximately at the time of complete transmission of the energy on the capacitor 20 by triggering the gas discharge tube 21. Through this a way is created through which the energy stored in the capacitor dem Emission path of the magnetron oscillator 11 is supplied. When the capacitor 20 is completely has discharged through the magnetron, there is no longer any voltage at the anode of the gas discharge tube 21 be present, so that their discharge process is extinguished.

The tubes 19 and 21 are controlled by a timing pulse supplied by a suitable source 23, which in the drawing is a square wave generator is indicated. The output of the source 23 is fed to the grid of the tube 19, so that the reverse bias provided by battery 22 is overcome, as in the next Paragraph should be explained in more detail. Similarly, the output of the source 23 is via the Delay circuit 24 is fed to the grid of tube 21, normally carried by the battery 25 originating grid bias is blocked.

The details of the mode of operation of the system can best be explained with reference to the graphs of FIGS. 2, 3 and 4, in which the curve values of the various voltages and currents are plotted against time. After that, immediately before time ij, the voltage E _{1 of} the source 23 is equal to zero and the tube 19 is blocked. Similarly, the voltage E _{2 applied} to the grid of tube 21 is zero and this tube is also blocked. Accordingly, the voltage V _{1 is} the

is indicated in Fig. ι between the right terminal of the coil 18 and the earth, equal to the voltage V _{0 of} the battery 17, as shown in FIG. At this instant, the current I, as shown in FIG. 4, is zero. At the time t _t , the voltage E ₁ applied to the grid of the tube 19 becomes positive, releases the tube and allows an emission current to flow. The voltage V _x then drops substantially to ground or zero potential because of the negligible resistance of the emission path of the tube 19. The current I ₁ then begins to flow through the coil 18, as shown in FIG. 4, the current being gradual increases with time, as are known ratios in an inductive circuit. At time t _{2 , the voltage .E 1} applied to the grid of tube 19 drops to zero and cuts off the flow of current through the emission path of tube 19. However, due to the induction effect of the coil 18, the current tends to continue to flow in the same direction through the capacitor 20 and the diode 26 and to charge the capacitor 20. This state remains until the energy stored in the magnetic field of the coil 18 is transferred to the dielectric field of the capacitor 20. At the same time, the voltage V _{1 is built up} across the capacitor.

The energy stored in the magnetic field

is represented by the equation W = - LI *,

where L is the inductance of the coil 18 and / the current flowing through it. Similarly, the energy in the electrostatic field is expressed by the equation W = CV _c ² , where C is the capacitance of the capacitor and V _{c is} the voltage across the capacitor. If the loss is neglected, the entire energy stored in the magnetic field is transferred to the electrostatic field,

L / ² = CV / or V _c =

As a result, the correct selection of the circular constants enables the voltage across the capacitor to be built up to a high value which is a multiple of the voltage V _{0 of} the battery 17.

At time t ₃ , the voltage E ₂ applied to the grid of tube 21 becomes positive, the discharge of this tube being triggered, so that the resistance of its emission path drops essentially to zero, with the result that voltage V ₁ drops to zero or Ground potential drops and the capacitor 20 is discharged through the magnetron 11, the resulting voltage V ₂ across the magnetron being represented by the curve in FIG. 3 and the current through the magnetron by the negative pulse of the current L ₁ in FIG. 4 .

As soon as the capacitor 20 is discharged, the gas tube 21 is blocked due to the lack of a positive one Anode voltage. The circle is then brought to its idle state, the one at the beginning of the

Description of its mode of action prevails. It remains in this state until the voltage E ₁ becomes positive again at time f ₄ , the effective part of the operating period then being repeated.

It appears that the timing of the discharge of the gas tube 21 is very critical to the effective operation of the system. If, therefore, the discharge is triggered before the time t _a , the voltage of the capacitor 20 will not have reached its full value, since the complete transfer of the energy to it has not yet been completed. Similarly, in the absence of any control effect, the capacitor 20, after it is fully charged by the energy from the coil 18, is discharged back into the coil, following the process of an oscillatory circuit known per se. If, as a result, the discharge of the tube 21 is not _{triggered until after the point in time i 3} , the capacitor voltage will again have fallen below its maximum value as a result of the energy return. The triggering of the gas tube is therefore controlled by the same voltage source 23 which determines the operating period. The required interval between the cutting off of the current supply to the coil 18 from the battery 17 and the triggering of the tube 21 is determined by the delay circuit 24.

In Fig. 5 a modification of the system according to the invention is shown in which the Discharge of the capacitor can be viewed as self-controlled. Except for the use the saturable or non-linear induction coil 30 instead of the gas tube is this Circle identical to that of FIG. 1, so that corresponding parts have the same reference numerals wear.

In known technology, an induction coil has ioo of this type a magnetic core that is easily saturable and has a high permeability with very little Has a flux density, which is very similar in effect to a switch. It therefore has a high Impedance at small current values, while already at a certain small current value the core is saturated and the impedance suddenly drops to a very low value, the process of insofar as it concerns the effect in the associated circle, as analogous to the closing of a previously gen open switch corresponds.

The effect of the non-linear induction coil 30 can be seen in FIG. 6, in which the current is plotted against time, the times t _v t., And i ₃ corresponding to the time intervals as they are for the operating conditions of the circuit in FIG. 2 and 3 are indicated. Since the voltage on the capacitor 20 builds up during the interval from t ₂ to i., A low current value flows through the induction coil 30, the value of the current L ₃ in the coil being small due to the high inductance in this unsaturated region is held. The current scale in Fig. 6 is greatly enlarged compared to that of Fig. 4. When the saturation value of the current / _{0 is} reached, the inductance falls and consequently the impedance

Pedanz of the coil 30 very suddenly to a very low value, which allows the discharge of the capacitor 20 through the coil 30 and the magnetron 11, so that the current, as indicated, rises to a high peak value. For the effective operation of the system it is necessary that this saturation value of the current is reached at the time i ₃ , when the voltage of the capacitor 20 reaches a maximum. To facilitate this critical adjustment, the use of a bias winding 31 on the core of the coil 30 has proven advantageous.

The blocking capacitor 32 prevents the establishment of a constant flow of direct current through coil 30.

FIG. 7 shows a modification of the circuit to the right of the dash-dotted line X-X in FIG. 1 or 5. In some embodiments of the invention, the circuit change shown in Fig. 7 has changed Proven to be advantageous, particularly with regard to the shape of the pulse. At this A modification is a delay coil 36 between the anode and the cathode of the diode 26 switched. The cathode of the magnetron tube is also given a small positive bias with the aid the capacitor 34 and the battery 33.

The delay coil 36 provides a dissipation path to prevent static charges from building up the cathode of the magnetron 11 remain.

In a circuit of this type, the diode is assigned a function which it must assume in addition to the task of forming a path for the charging current to the capacitor 20. This can be referred to as a pulse shaping or trimming effect. An analysis of this effect is based on the fact that it is a characteristic of a magnetron oscillator of the shape of the magnetron 11 that at low anode voltages (below about 50 to 60% of the optimum value) its output power drops and its effective anode-cathode impedance decreases completely suddenly increases. This results in a residual value remaining in the circle after the useful pulse. Without control, this voltage would result in a sequence of damped oscillations in the reactances given by the coil 36, capacitance 20 and the stray capacitances outside the circuit. Such an oscillation actually occurs, but is effectively damped by the diode 26 when the polarity is reversed for the first time. Since this polarity can not stimulate ¹ the magnetron 11, she has no disturbing. Effect. The bias voltage provided by the battery 33 prevents the magnetron from being excited by residual energy which may persist for the next half period of the damped oscillations.

Although this description relates only to particular embodiments of the invention, it is obvious that various other forms and alterations are possible without the to deviate from the principle of the invention.

Claims (5)

PATENT CLAIMS: 1. Transmitter arrangement with an oscillating tube, for example a magnetron and a sensing circuit for the delivery of tactile pulses to this, characterized in that a Choke coil and a capacitor are provided as well as means for supplying direct current to the choke coil and its periodic interruption so that energy from this is transferred to the capacitor and other means of sudden discharge of the Capacitor across the vibrating tube at the time when the energy transfer from the coil to the capacitor is complete. 2. Arrangement according to claim 1, characterized in that that the direct current flow through a control tube, which at predetermined intervals is made non-conductive, is controlled. 3. Transmission arrangement according to claim 2, characterized in that a timer control arrangement is provided that has a control potential of the control tube and with a suitable Delay supplies a control potential of an electron tilting device which is used for Discharge of the capacitor is used. 4. Transmitter arrangement according to claim 1, characterized in that the discharge of the capacitor is effected by a saturable induction arrangement which is designed to reduce its saturation inductance in the The moment reached in which the voltage across the capacitor reaches its maximum value. 5. Transmission arrangement according to one of the preceding claims, characterized in that that a diode bridges the transmitter tube, so that the cathode of the diode with the anode the transmitter tube and the anode of the diode is connected to the cathode of the transmitter tube. 1 sheet of drawings O 1334 8. 51