DK150874B - MULTI-STEP CLASSIFICATION DEVICE FOR HIGH-FREQUENCY SIGNALS - Google Patents

Abstract

1. High-frequency multiple-distribution circuit arrangement for signals in the VHF-UHF range (5-860 MHz), particularly for use in community antenna systems, comprising at least two cascade-connected directional couplers for the broad-band direction-dependent coupling of a part of the signal energy conducted via a trunk line onto a distribution connection (AB), said directional couplers being of different design such that - coupled in alternating sequence - they consecutively transform the respective input impedance up and down, wherein each directional coupler exhibits two separate transformers (Ü1 , Ü2 ) whereby the primary winding of the first (current) transformer (Ü1 ) is between the input (E) and the output (A), that of the second (voltage) transformer (Ü2 ) being between input (E) or output (A) and ground, and the secondary winding of the current transformer (Ü1 ) is connected firstly to ground and secondly to the secondary winding of the voltage transformer (Ü2 ) whereby in the case of the step-down directional couplers (type A) the distribution connection (AB) is between the two secondary windings and the other end of the secondary winding of the voltage transformer (Ü2 ) is connected via an ohmic resistor (R1 ) to ground while in the case of the step-up directional couplers (type B) the resistor (R2 ) is connected between the connecting point of the secondary windings and ground and the other end of the secondary winding of the voltage transformer (Ü2 ) forms the distribution connection (AB).

Description

in 150874

BACKGROUND OF THE INVENTION The present invention relates to a multi-stage, high frequency signal stripper and of the kind set forth in claim 1.

Such branching devices are used, for example, in common antenna and cable television systems to transmit signals with specific, identical or different attenuations from a trunk or main line to transmitting wires, distribution devices or directly to antenna sockets. In this way, it is already to be ensured in the subscriber network, but especially when used in general networks, for the total operating frequency range, that the branching device is always adapted at random decoupling damping to the wave resistance of the connected wires and such a large coupling damping between all outputs.

15 A multi-stage branching device of the aforementioned kind is known from DE-B 24 25 722. By this the said requirements have been sought to be fulfilled, but it has only succeeded insufficiently so that this known branching device is in practice useless in several contexts. In practice, branching devices of the kind known from DE-A 23 43 403 and 27 03 258 as well as DE-B 24 48 737 and 26 06 449 are used, but due to series connection of similar directional couplers which transform all input resistors of In the same way, according to the lower-value writings mentioned, 25 are already obtained at a few branches unacceptable adjustment and there with also decoupling. Some of the compensation known from DE-B 24 25 722 of alternating up and down transformer directional couplers is obtained, but this is insufficient, especially with a large number of branches.

30 Already at two stages with 14 dB switch-off attenuation according to fig. 5 of DE-B 24 25 722, an input impedance of 75 ohms is transformed to an output impedance of at most (and frequency dependent) 60 ohms. This deviation becomes even greater at branches with poorer cut-off damping. A first-branch adjustment of about 60% is in many cases sufficient, whereby a choice between the resistor R must be compromised between decoupling and adaptation, but second branching transformer or the additional adaptation resistance R1 proposed in the specification specification. These measures not only result in additional component supply, but also increase the cut-out damping further, so that the actual directional coupler must be sized for a smaller cut-off damping. Thus, the throughput attenuation is increased, the series coupling becomes asymmetric, the desired uniform transformation conditions are less consistent and the coupling becomes inferior. In practice, it is desirable that all receivers in a common antenna system be supplied at approximately the same signal level. For this, the cut-out damping must be greater at the beginning of a trunk line than at its end. For longer trunk lines, relatively lower cut-off attenuation is also needed, in extreme cases up to 3 dB. Branches whose cut-off attenuation is less than 10 dB have so far not been able to respond with sufficient return attenuation. In the branching device known from DE-b 24 25 722, the said defect for smaller switch-off dampers becomes even worse, with the matching resistance R 1 having to increase the 20 already mentioned result. All in all, in this known multi-stage branching device it is not possible to realize neither major series couplings nor branches with cut-off at less than 10 dB and satisfactory electrical properties. Furthermore, cf. the characteristic part of the main requirement, 25 need to take special, cost-increasing measures to expand the UHF range up to 860 MHz.

The object of the present invention is to provide a multi-stage branching device of the kind specified in the preamble of claim 1, whereby in the entire operating frequency range it is possible, regardless of the number of successively coupled directional couplers, to achieve a large decoupling between all outputs, a good adaptation everywhere and small cut-off dampers.

This is achieved according to the invention in the embodiment of claim 1.

The invention will now be explained in more detail in connection with the drawing, in which fig. 1-4 show basic forms of directional couplers according to the invention, Figs. 5-7 branching devices composed of directional couplers according to fig. 1-4, and FIG. 8 schematically shows the mechanical structure of a branching device according to the invention, 5 etching couplers according to the present invention occur in two basic forms and the corresponding dual forms as shown in Figs. 1 and 3, respectively, Figs. 2 and 4. The figures shown in Figs. 1 and 2, respectively. (type A) transforms the input impedance to lower value, while the (type B) shown in Figs. 3 and 4 transforms 10 to higher value. Thus, it is possible to obtain compensation by alternately placing the two types in series.

This up and down transformation becomes optimal when directional couplers according to Figs. 1 and 3 and Figs. 2 and 4, respectively, follow alternately one after the other. In the former case, by ideal decoupling (infinitely large coupling damping between branch and output) and terminating the free connections with the wave resistance of the connected cable, the following values are obtained: * coupling according to fig. 2, coupling according to fig. 3 2nx ~ «i 7 tf \ 2ηι + 7ί * ~ Ζ .γ (- Z i *** + & - 'Zi Zi z« ZL di) ZL (Zt) “A ZoeujTr (lOdB) 20 took £ (JodB) ZOtogj ^ j (o & dB) 20 & gg £ = $ (W · *)

(4- τχ) · Ζ. (0.92.'i)

In the above scheme, n is the winding ratio of both transformers in the directional coupler, Z 1 is the wave resistance of the connected wire, Z g, Z 2 and Z 2 g are the input, output and branch impedances, a.

From the formulas given by calculation, it can be immediately recognized that by serial connection of the two directional couplers, thus the input of the second directional coupler is not terminated with Z 1, but with the output impedance Z 1 of the first directional coupler, all impedances are frequency independent equal to the wave resistance Z 1, so that, with ideal decoupling, there is versatile adaptation when the resistors R 2 and R g are dimensioned according to the decoupling conditions specified. By way of example, in the above scheme, the values calculated for a two-stage branch 15 with a cut-off at 10 dB (n = 10) are indicated in brackets. "

Obviously, the values found in computational technology are not completely achieved in practice. The deviations from the theoretical ideal values can mainly be attributed to: 1) that the available resistors will generally not exactly 20 correspond to the calculated values and, like all other components, have a certain tolerance, 2) that the winding ratios at realistic winding ratios are usually not can be accurately realized or that to obtain certain desired values of the cut-off damping must be chosen differently for the two transformers, for which a value which gives a compromise between good fit and high decoupling must be chosen, and 3) that, at determined constant signal energy decoupled from the trunk line from the cut-out attenuation of the nth directional coupler, the value (nl) a ^ is deducted.

However, some deviations are relatively small, so that measured values are in good agreement with those calculated and are at least far better than similar ones in known branching devices. Thus, a two-stage branch with each 14 dB switch-off attenuation according to the invention exhibits a direct comparison with that of FIG. 5 in BE-b 24 25 722 the following values are 5 150874

WF UHF

Return attenuation ωγε ^ 30118 arA.

rAB1> 25dB> 2odB

arAB2

Stem crossing - a <-idB <2dB

attenuation d

Coupling Attenuation εαβί-α

> 30dB

aAB2-A

-__ __ ^ - η | - - «----- - - -„ -r-, -, - - - -, -----, r

All in all, the invention thus achieves a multi-stage branching device which, with extremely low range of components, has substantially better properties than the known ones.

In the embodiment of claim 2, a low-pass compensation is obtained, whereby the frequency range can be increased at the lower end in a simple and inexpensive way.

In the embodiment according to claim 3, a material saving is obtained which is particularly advantageous when a plant comprises a large number of branches. Furthermore, the resulting inductance decreases less sharply than when a separate primary winding is used for each transformer, so that about half instead of only about a quarter of the single winding inductance is effective, which results in a further reduction of the lower limit frequency. . Finally, in this embodiment, a smaller throughput attenuation is obtained, for example at 1 dB for a two-stage and 2 dB for a four-stage branching device with 14 dB switch-off at each stage. In theory, it is possible to build a branching device with any number of branches and only a single primary winding common to all voltage transformers. In practice, however, manufacturing problems are encountered when assembling more than 8 directional couplers. This is mainly due to the spatial dimensions at higher frequencies, and if the secondary windings consist not only of half, but of a whole or even several turns, difficulties with the winding.

The configuration of claim 4 is particularly advantageous in cases where particular emphasis is placed on high decoupling, for example as VHD / UHI 'separator or for measuring purposes.

10 Use of the device shown in FIG. 5 as a match box design is particularly advantageous because of the large decoupling value (without filter) obtainable (> 50 dB between different cans). As a result, separation means for sharing in the I'M and TV frequency ranges are not necessary, as they are found in the input of the respective receiver. Thus, such antenna sockets are also distinguished by a very small component range. And both branch connections can optionally be used for EM or TV receivers. Hereby, such antenna sockets are not only preferable for the socket without directional couplers (which require many filter components) but also preferable for such directional coupler boxes known from, for example, DE-A 23 09 151. Ted these are decoupling sufficient in normal cases, but When transmitting TV in the lower channels and of the EM at the upper end of the EM band, 25 additional filters are needed in the case of, for example, short-circuiting or idling on a receiver connection cable. Further, a loss of approx. 3 dB inevitably due to different in all forms of the radar, whereby at a certain switch-off attenuation one of the directional switches must be inferior, which further causes an increase in the attenuation attenuation.

In contrast, despite the use of two directional couplers with only slightly greater throughput attenuation, the coupling according to the present invention requires a substantially smaller component range (especially in the configuration of claim 3).

For such applications, it is advantageous, especially with many antenna sockets, to use the design according to claim 6, where at each branching connection the maximum possible signal energy is available, where the decoupling at phase-correct coupling of the two directional couplers is dB lower than for single-directional couplers * Admittedly, at these selective branches, not only are the component supply larger, also the values of the return attenuation at the receiver connections and the coupling attenuation between them are not quite favorable. However, this disadvantage is, in the case of antenna sockets, usually as minor as the fact that each of the two connections is firmly assigned a partial frequency range (TV or PM) and not applicable to both areas.

In order to further improve the throughput attenuation and the return attenuation for all connections, it is expedient as described in claim 7 to take the measure known per se from DE-A-27 03 258. In the design according to claim 8, a substantial manufacturing technical simplification of the structure is achieved. and thus a considerable reduction in manufacturing costs.

This is especially true for multi-stage branches with voltage transformers, whose secondary winding comprises only half, through winding through the core bore.

Figures 5-8 show three embodiments of a multi-stage branching device according to the invention as well as the winding diagram of yet another embodiment.

Pig. 5 shows a two-stage branch with two types B and A directional couplers coupled together and a coupling capacitor 0 for extending downwards of the operating frequency range. This embodiment has all the advantages described in connection with claim 1, since in idea decoupling an exact compensation is obtained by means of the two opposite impedance transformations and thus good adaptation and minimal throughput attenuation. The coupling works with these good electrical properties in the 5-860 MHz range.

In the embodiment shown in FIG. 6 shows only a single primary winding and a single core for the voltage transformers.

This embodiment, compared to the use of a primary winding for each voltage transformer, not only provides a saving of materials and manufacturing costs, but also a minor lowering of the resultant inductance of the voltage transformers primary and thus a lower raising of the lower limit frequency.

5 Furthermore, it is compared with one in accordance with FIG. 5, four-stage branching, due to less core and scattering losses, is possible to achieve a significant reduction in the throughput attenuation (up to 2 dB using 14 dB directional couplers). Finally, this design allows for a star-shaped structure, which in many cases gives a spatially smaller and more favorable structure for the connections.

In FIG. 7, there is shown a branching device for antenna sockets in which the measures 15 according to claims 3 and 7 are combined. This results in an antenna socket which, at maximum energy transfer at the receiver connections and relatively low component supply, exhibits a small throughput attenuation. The opportunity thus obtained for cascade coupling is particularly important in the case of precisely antenna sockets, where in practice this is of great use.

In FIG. 8 shows how simply and clearly a two-stage branch with a cut-out attenuation of about 14 dB can be constructed by two directional couplers according to fig. 3 and Fig. 1, respectively, using the simplification set out in claim 3.

The use of the resistors E ^ and Eg wires as secondary windings in voltage transformers permits a very low cost fabrication.

Claims (9)

150874 Patent Claims. 1. Multi-stage branching device for high frequency signals in the VHF and UHF range (5-860 MHz), especially for use in common antenna systems, and consisting of at least two in series coupled directional couplers for broadband, directional decoupling of a portion of the above a trunk leads signal energy to a branching connection, which couplers are so differently designed that they interconnect in alternating order respectively up and down transform the input impedance, characterized in that each directional coupler comprises two mutually separate transformers (u ^, ^), the first (primary transformer (ti · ^) primary effect lies between input (E) and output (A), and the other (voltage) transformer ($ 2) primary winding lies between input (E) or output (A) and frame, while the first (current) transformer (ii ^) secondary winding is connected partly to frame and partly to the second (voltage) transformer (tig) secondary winding, and that the branch connection (AB) of the down transform Current directional coupler (type A) at the common point of the two secondary windings and the second (voltage) transformer (tig) secondary winding 20 is connected to the frame via an ohmic resistor (R 1), while the branching connection (AB) of the preamforming directional coupler ( type B) is the free end of the second (voltage) transformer (^) secondary winding and the common point of the two secondary windings is connected to the frame via an ohmic resistor 25 (¾). 2. A branching device according to claim 1, characterized in that each of two successive directional couplers is interconnected via a capacitor (C) included in the trunk line, 5. A branching device according to claim X or 2, characterized in that the other (voltage) transformers (ΰ2) in at least two directional couplers have common primary winding. A branching device according to claims 1-3, characterized in that neighboring switches two and two constitute a two-stage branch and that the two branching connections 150874 ίο (AB1, AB2) are switched on selection means (s, p) through which a part of the frequency range can pass by. Branching device according to claims 1-3, characterized in that neighboring switches two and two are built into an antenna socket. A branching device according to claim 4, characterized in that the branching composed of two directional couplers is built into an antenna socket and that the selection means consist of between each branching connection 10 (ABI, AB2) and the TY antenna socket (FS) and the FM antenna socket respectively. (UKW) positioned the FM frequency range blocking parallel resonant circuits (P), respectively, matched to the FM frequency range, resonant resonant circuits (s). Branching device according to claims 1-6, characterized in that the transformers have pipe cores, the volume and / or the relative permeability of the first (current) transformer (Q 1) being less than that of the second (voltage) transformer (tig), that the secondary winding of the first (current) transformer is uniformly distributed along the circumference of the core, while the secondary winding of the second (voltage) transformer (tig) has closely superimposed turns and that the primary winding of the first (drill) transformers (ίί ^) core drilling has a constant distance to the secondary winding. A branching device according to claims 1-7, characterized in that the secondary transformer (tig) secondary winding is constituted by one of the resistors (E ^ jSg) of the resistors.