DE1200394B - Tunable pot circle - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

H03h

German class: 21 a4 - 69

Number: 1200 394

File number: T 26787IX d / 21 a4

Filing date: August 12, 1964

Opening day: September 9, 1965

The present invention relates to a tunable pot circle, in particular for UHF channel selectors, with a coupling conductor arranged in the vicinity of the inner conductor.

It is particularly useful for voting units with pot circles, preferably of channel selectors for the UHF range, known, parallel to the inner conductor a coupling conductor for coupling or decoupling of high-frequency energy to arrange. The degree of coupling is achieved by changing the distance between the inner conductor and coupling conductor adjustable within certain limits.

However, this coupling arrangement is frequency-dependent, in such a way that with decreasing frequency the degree of coupling is also smaller and the transferable bandwidth of the pot circle is reduced. At the same time, the high-frequency energy that can be coupled in or out also falls, even if the conditions are otherwise the same.

The object of the invention is now to provide a pot circle with one coupled to the inner conductor Train coupling conductors so that at low frequencies an approximately equal degree of coupling is achieved as with high frequencies.

Accordingly, the invention is characterized in that on the facing away from the coupling conductor Side of the inner conductor in a mainly at running frequencies of the tuning range on the High-frequency power line involved section of the pot circle wall a resistor is switched on.

This ensures that at low frequencies the wall currents mainly in the coupling conductor surrounding part of the cup circle wall flow, whereby the magnetic and electrical Field at the low frequencies is particularly strong in the space around the coupling conductor and an increased one Degree of coupling causes. This can be achieved by appropriately dimensioning the resistance according to a preferred embodiment of the invention is designed as a slot in the pot circle wall, in adjustable to certain limits.

Further advantageous details of the invention are explained in more detail below with reference to the drawing of an exemplary embodiment which represents a high-frequency filter arrangement of a channel selector for the UHF range in λ / 4 pot-circle technology.

An electrically conductive housing 1 is divided into chambers by partition walls 2, 3, 4, which together with inner conductors 5, 6 and variable capacitors 7, preferably variable capacitors, Form resonance lines, in particular a two-circuit band filter. One end of the indoor tunable Pot circle

Applicant:
Telefunken

Patentverwertungsgesellschaft mb H.,
Ulm / Danube, Elisabethenstr. 3

Named as inventor:

Dipl.-Ing. Hermann Zierhut, Ingolstadt;

Fritz Gugel, Langenbruck

Conductor S, 6 is connected to the housing 1 in an electrically conductive manner, and the stator laminations of the rotary capacitors 7 are arranged at the other end. the

so common axis 8 of the variable capacitors 7 penetrates the partition walls 2, 3 and 4 and has the same potential as these. In the vicinity of the Inner conductor 5 and on the side facing away from intermediate wall 3 thereof is preferably parallel

A coupling conductor 9 is arranged for this purpose, by means of which the high-frequency energy is decoupled from the inner conductor 5 and conducted to a control electrode of a subsequent amplifier or mixer element, preferably a transistor 10. A trimmer capacitor 11 is connected to each of the ends of the inner conductors 5 and 6 connected to the variable capacitor 7 and is preferably soldered to the housing with a covering.
According to the invention is in the mainly at deep

fen frequencies on the power line involved part of the cup circle wall a high resistance switched on, which is preferably used as a continuous gap 13, in particular between one for fastening 12 and the partition 3 is formed.

for the inner conductors 5 and 6 serving housing wall between the two cup circles is a coupling loop 14 is provided, which is passed through the gap 13, so that no special implementation is required, it ends in a pot circle, preferably on the two common Wall 3.

The mode of operation of the arrangement according to the invention is as follows: At the upper frequencies of the tuning range, the required degree of coupling is achieved by approximating the Coupling conductor 9 is set to the inner conductor 5. The high-frequency current flow then runs because the incoming

509 660/187

Corresponding variable capacitor has only a very small effective capacitance in the twisted state, mainly from the inner conductor 5 via the trimmer 11 and the housing 1.12 to the base of the inner conductor 5 back. The partitions 2, 3 are only a negligible part of the 5 RF power line involved.

At the lower frequencies of the tuning range, on the other hand, the HF current mainly via the screwed-in variable capacitor 7, the axis 8, the partition walls 2 and 3 and the housing wall 12 to the base of the inner conductor 5. But now with the object the invention of the current path through the partition 3 through a gap 13 between the housing wall 12 and intermediate wall 3 formed resistance becomes higher, more HF current flows over the partition 2 and adjacent housing parts. This makes the electrical and magnetic The field at the low frequencies is more concentrated on the space around the coupling conductor and thus the degree of coupling increases. In particular, through suitable dimensioning and arrangement, the Resistance path of the current flow so controllable that for the high as for the low frequencies an approximately the same degree of coupling is achieved. That means constant values for a voting system Bandwidth and gain over the entire tuning range.

The invention is not limited to the illustrated embodiment, in which the gap between Housing wall 12 and partition 3 in a particularly advantageous manner at the same time for support the coupling between the two cup circles shown as band filters is used, but also with pot circles in a different circuit and a different structure and especially with channel selectors with pot circles for the UHF range.

The invention is not restricted to A / 4 tuners, but can also apply to A / 2 tuners, for example and other constructions of pot circles are used. You only have to pay attention to that the resistance is in the right place, e.g. B. in the power belly is arranged. It may be enough it is sometimes not to position the resistor exactly in the belly of the current, but further away from it removed, possibly even near the tension belly. Of course, the Effect.

In order to increase the effect aimed at by the invention, the inner conductor can be added to the Wall 3, in which the resistor 13 is provided, be shifted. In some cases it can be beneficial be to increase the effect in this way and the gap 13 or the resistance to one for other purposes more favorable place, but where the effect is less favorable than when it is in Current belly would be arranged. This can be useful if the gap 13 z. B. at the same time to serve as a coupling slot, for example between two pot circles.

The resistor cannot only be designed as a gap 13. So it is sometimes useful that Partition 3 at a suitable location, e.g. B. at the point of the gap shown in the drawing 13, by a smaller material cross-section and / or by using a material with a higher to establish specific resistance. The material used can optionally be semiconducting or non-conductive dielectric or some other semiconductor.

In addition, the invention can also be used with bowl circles that can be tuned inductively or inductively and capacitively Find use.

Claims (10)

Patent claims: 1. Tunable pot circle, preferably for UHF channel selectors, with one near the Inner conductor arranged coupling conductor, characterized in that on the Coupling conductor (9) facing away from the inner conductor (5) in a mainly at low frequencies of the tuning range on the high-frequency power line involved section of the cup circle wall, a resistor (13) switched on is. 2. pot circle according to claim 1, characterized in that the resistor (13) through a gap is formed. 3. pot circle according to claim 1 or 2, characterized in that the resistor (13) optionally is also formed by a thinner cross-section of the pot circle wall. 4. pot circle according to one of claims 1 to 3, characterized in that the resistor (13) by a material with a higher specific resistance than that of the cup circle wall is formed. 5. pot circle according to one of claims 1 to 4, characterized in that the resistor (13) is formed by a material with semiconducting and / or dielectric properties. 6. pot circle according to one of claims 1 to 5, characterized in that the resistor in a common cup circle wall (3) present between two cup circles is provided. 7. pot circle according to claim 6, characterized in that a coupling loop (14) of one cup circle to the other through the gap (13) serving as a resistor is. 8. pot circle according to claim 1 or one of the following, characterized in that the Cup circle inner conductor is shifted towards the wall containing the resistor (13). 9. pot circle according to one of claims 6 to 8, characterized in that the resistor (13) is also used for coupling. 10. pot circle according to claim 1 or one of the following, characterized in that the Resistance (13) is provided at least in the vicinity of the current bulb. 1 sheet of drawings 509 660/187 8.65 © Bundesdruckerei Berlin