DEP0000286MA - Discriminator circuit for very short waves. - Google Patents

Description

"Ρ ATELHOL D ^m
Patentverwertungs- & Elektro-Holding AG _es GLARUS (Switzerland)

Di8criminator circuit for very short waves.

The invention relates to a discriminator circuit with a tuning circuit which is tuned to the mean pass frequency and which has a tuning coil provided with a center tap. The two ends of this tuning are "connected to one rectifier Diebeiden rectifiers are consecutively JGT # ee""efigeschaltet _s that a differential voltage is created. This differential voltage is the demodulation voltage and is directly dependent on the frequency of the applied high-frequency input voltage. The high-frequency input voltage is connected to the coil tap. In the known circuits, this coil is magnetically coupled to the coil of an oscillating circuit connected to the input voltage and tuned to the mean frequency. When using a similar circuit working with magnetic coupling for very high frequencies, _{e.g. 0} greater than 20 MHs, capacitive couplings are also noticeable in addition to the desired magnetic couplings &

The capacitive couplings are due to the at high frequencies increasingly coming into Erscheiniurig inevitable coupling capacitances between the lines _e Dl simultaneously coupling by the magnetic field and the elelctrische field resulting in undesirable side effects "can be remedied by adding at high frequencies on the magnetic coupling dispensed with and only used capacitive coupling

The present invention is also concerned with the purely capacitive coupling, this Coupling is achieved in a particularly simple manner, which is very desirable at very high frequencies «

The invention consists in that the two coil halves caused by the center tap Tuning coils are firmly coupled to one another and that of the one coil end an additional capacitive coupling against earth,

The invention is based on drawings

explained in more detail *.

Figel shows a circuit example of the invention * Fig, 2 shows a particularly favorable arrangement of the tuning coil β

Across the output terminals 31, 32, the frequency-modulated high-frequency voltage is supplied · This voltage is fed from the capacitor 5 to the center tap of the tuning I _e d According to the invention, the

Coil 2 tightly coupled coil halves 1 'and 1 "on. The capacitor 3 is connected in parallel to the sink. Coil and capacitor form an oscillation circuit which is tuned to the mean frequency of the oscillation to be demodulated 7 The cathodes of the rectifiers, connected in push-pull via their anodes, are connected via the resistors 8 and 9 of the same size, parallel to this is the capacitor II _s, which formed a short circuit for the high frequency which are still present on the direct current side _i are diverted to earth via the capacitor 12 The middle of the voltage

10

divider 8,9 is connected via the choke coil * / to the center tap of the coil 1 »According to the invention is between

and Ecde ^

one end of the coil 3 has an additional capacitive coupling formed by the capacitor 4.

The mode of action is as follows: First of all, it is assumed that the additional capacitive coupling through the capacitor against üirde does not exist; furthermore, they are due to their own capacities of the coil ends and the anode lead exi the primary capacitances 21, 22 of the same size. If now via the capacitor 5 the frequency-modulated high-frequency voltage U, from which the center tap of the tuning coil is effective, also occurs;

the same voltage tmcf with the same phase at the ends of the coil because the coil halves are tightly coupled. , The partial voltages H ₀ and U, at the coil halves are C. Accordingly, the resonant circuit voltage Ug and is also equal to zero and a demodulation voltage cannot occur. If the capacitor 4 is now switched on, the voltage conditions change completely because the symmetry of the earth capacitances is disturbed. It flows over the spool half. I ⁿ an additional current J ^ has a voltage to a row and £ e 'due to the fixed coil coupling ~ in the other coil half an equal voltage U ^ Yinduziert w "This contact the rectifiers the desired voltages Ug and U ^ on which with the input voltage U ^ interact vectorially in a known manner.

If the frequency of the input voltage of the mean Fredie ^l \

frequency / coincides with the resonance frequency of the oscillating circuit

Ui

true, frequency ^ modulates wweV, the demodulation voltage U * occurs at terminals 33 and 34.

In the circuit / the invention, no inductive coupling to the tuning circuit is required. This is a great advantage at very high frequencies, because there inductive coupling is more difficult to produce and the internal capacities and the Coupling capacities of the lines to earth and among themselves

appear more and more strongly. The circuit makes it possible ^ to get along with these capacities alone. The production the asymmetrical .Crdkapazitat formed by 21 and 22 + 4 is very simple. A small one is sufficient for this Capacity of a few cm. Often the asymmetry of the available external capacity is sufficient.

The tuning coil with the coil halves I ^f and 1 "is expediently designed as a short multi-layer coil. The scatter between the two coil halves is then relatively small, about 5-20 ^, so that the coils can be viewed as firmly coupled. Fig.2 shows the LÖLnQS cut

Qa · through such a coil. The actual winding is carried out in layers, wherein purpose bulky litz used TSird ₀ Thus, the coupling of the Spulenhalften

the

is as firm as possible without own capacities becoming too large at the same time, it is recommended that the ratio the coil length to the waist height should not be greater than 2 and not less than 0.5. Xm inside the bobbin is • · practical a core made of high-frequency iron is provided, which makes the ratio of leakage inductance to coil inductance particularly small and thus the coupling of the two reel halves can be made particularly tight.

The windings and the core »ground

Λκφ bioJi ίη ^ *

partly housed 4 ä '^ Tnem cylindrical bobbin ^ made of insulating material, by moving the core

The inductance can be easily adjusted in the axial direction. The displacement of the core can it is expedient to achieve that the coil body and the core piece have a thread. Through By turning the core, the core can be adjusted in the axial direction®

Claims (1)

Patent application g see tuning coil, the ends of which are each connected to a calibration judge aind ^ for ultrashort waves ^ characterized by that the two coil halves caused by the center tap are firmly coupled to one another and that of at one end of the coil there is an additional® capacitive coupling to earth® 4 / l 'X) Discriminator circuit according to patent claim ^ characterized in that the additional capacitive coupling through unequal Brdkapkapisten the lines lying at the coil ends after the rectifiers 4> ejLislil * go Ldet wli <üL. indicates that "ae line is connected to ground after the one line of equation" ichoi y, p) Discriminator circuit according to claim / Γ characterized in that the tuning coil is wound in several layers β 4) Dialcriminator circuit according to claim \ _f, characterized in that the tuning coil has a coil core made of high-frequency iron _β / 4 f j $) Discriminator circuit according to claim j> _t through this marked that the coil length to the winding height is not greater than 2 and not less than 0.5 « ^m pateihoid ^m Patent utilization & Blektro-Holding a _e g ₀