DE1037530B - Arrangement for the electronic control of the retroreflective capacity of reflectors - Google Patents

Description

Arrangement for the electronic control of the reflectivity of Reflectors It is known that from a transmitter emitted electromagnetic Modulate waves by entering the field for recording and radiation Brings suitable housing of vibrations, which in turn has an oscillating circuit that is modulated. From this fact one has, among other things, to modulation of vibrations running in hollow pipes and for modulating radar reflectors Made use of. Here were to the waveguide or to a horn antenna as Hollow tube formed short-circuited line pieces coupled inside a modulating element, e.g. B. an electron tube or a crystal detector, was arranged, which was controlled by a special modulator.

Since the main area of use of controlled reflectors is identification of radar targets, the known arrangements are because of the separate oscillator and the associated relatively high power consumption is not very suitable. According to the invention it is therefore proposed that the modulating element simultaneously to be used for self-excitation of the oscillating circuit.

So you can directly insert the oscillator tube of the modulation circuit insert the connected piece of line. To further reduce power consumption it is advantageous to design the oscillating circuit as a transistor oscillator, whose transistor switched directly into the line carrying the high frequency will.

Such an embodiment is shown as an example in the figure shown. A short-circuited line section 2 is preferably attached to a horn antenna 1 coupled by the length / 4, inside of which there is a transistor 3, which is located in a self-excited oscillating circuit 4. The operating voltages Such modulators are of the order of a few volts, the power consumption in the order of 1 mA, the power consumption thus in the order of a few mW. It is therefore sufficient to operate miniature batteries or accumulators, so that the whole arrangement with very little effort. can be manufactured and operated.

The modulation can of course take place in any form, with it is advantageous for a clearly recognizable identifier to use it in a given time function, whose periodicity character can be changed over time to control.

PATENTASPRE: 1. Arrangement for periodic or non-periodic change the reflectivity of reflectors for electromagnetic centimeter waves, in particular for the identification of radar targets, in which the reflector is through a the line element corresponding to the wavelength of the incident radiation is shown whose adaptation to the element absorbing the high frequency energy (antenna) by inserting in their high-frequency resistance by means of one of a self-excited Oscillating circuit generated electromotive force changeable switching elements, preferably semiconductors, is influenced, characterized in that the adaptation of the conduction element to the antenna influencing and the self-excitation of the Oscillating circuit causing element are identical.

Claims (1)

2. Arrangement according to claim l, characterized in that the self-excited Oscillating circuit consists of a crystal amplifier. 3. Arrangement according to the preceding claims, characterized in that that for the purpose of marking or identifying the reflector its reflectivity influencing change in resistance a given time function of any form whose periodicity character is especially also variable over time. Documents considered: German Patent No. 423 813; British Patent Nos. 659969, 682 652, 723 815.