DE1051922B - Line arrangement tunable over a wide frequency range by means of a short-circuit slide - Google Patents

Description

GERMAN

The invention relates to an over a wide frequency range by means of a short-circuit slide Tunable, consisting of unslotted conductors, having an outer jacket, as a resonator Serving line arrangement, the wave resistance of which is swept over by the short-circuit slide Area after the short-circuited line end increases sharply or in a steady transition.

Line resonators that can be tuned over a wide frequency range, for example for Oscillators in the frequency range between 100 and 150O MHz are required, often consist of one High-frequency line section short-circuited on one side, whose short-circuit level for tuning is displaceable in the longitudinal direction of the line. Such resonators are, especially if there are are relatively low frequencies, unwieldy because of their great geometrical length, what about even the well-known design of a rolled-up Lecher line does not help significantly. To this To counter the disadvantage, it is known to make the line from individual sections of different wave resistance build up, since in this way a certain geometric shortening can be achieved. To the In these known arrangements, however, tuning has so far only been made in one of the sections, and although the one located directly in front of the short-circuit level of the tuning slide is provided. So that will but the tuning range is relatively small. It was already proposed in the main patent 1 015 873, this Difficulty to be met by the fact that the line sections have different wave resistance an outer jacket owning lines are provided and these lines and / or the Train short-circuit device so that a displacement of the short-circuit device over the sections the change in wave resistance is possible. In this context, it was also suggested that the characteristic impedance towards the short-circuited line end, preferably in a steady manner Let transition increase exponentially.

The invention is based on the object of providing a way in a further development of the older proposal show, which results in an advantageous design.

This object is achieved with an arrangement of the type mentioned in the introduction according to patent 1,015,873 solved the invention in such a way that the line section has the shape of a circular arc.

From US Pat. No. 2,752,594 it is known to slit the inner conductor of a coaxial line in a helical manner in a partial area. By utilizing the coaxial line vibration mode for short waves and the waveform in a helical cable for longer waves, a relatively wide frequency range is achieved
by means of a short-circuit slide
tunable line arrangement

Addendum to patent 1,015,873

Applicant:
Siemens & Halske Aktiengesellschaft,
Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Dipl.-Ing. Josef Gammel, Munich,
has been named as the inventor

wide tuning range obtained. However, the slotting of the inner conductor is structurally disadvantageous, because it requires a high level of precision to avoid reflections. Through the USA patent 2,463,417 a coaxial line is also known which has the shape of a circular arc and which has one around the center of the circle pivotable short-circuit slide is provided. To expand the tuning range of this known arrangement, however, contrary to the subject matter of the invention, an artificial extension the electrical length of the circular arc-shaped line through dielectric introduced into the line Material applied. The dielectric constant of this material must be graded in a special way which is very difficult to realize on the one hand. On the other hand, there is a special recess required in the solid dielectric, which can give rise to field distortions and the like. At the According to the invention, these disadvantages are avoided.

The invention is explained in more detail below with reference to basic circuit diagrams and exemplary embodiments which are shown in the drawings. In Fig. 1 the known embodiment of a line resonator is shown, which consists of a double line 1, V , which is short-circuited at one end and provided for connection at the other end. The input impedance R ₁ on the connection side, assuming negligibly low losses, is known from the condition R ₁ = j · Z · tg a I, where Z is the characteristic impedance and a is the phase dimension of the line section. In the event of a response

809 768/360

Claims (1)

tgal takes on the value Unendlidh, which also makes R1 infinite. On the input side, the line resonator thus exhibits roughly the behavior of a parallel resonance circuit. If, for example, as shown in FIG. 2, the line resonator is composed of two sections I1 and Z2 of different characteristic impedances Z1 and Z2, then the total length I = I1 + 12 when tuned to the same frequency as the resonator according to FIG. 2 is essential shorter than with this resonator. This is based on the fact that the resonance condition in this case depends on the wave resistances in the individual sections. For a resonator according to FIG. 2, the resonance condition is determined by the equation Z2IZ1 tg a I1 · tg a I2 = 1, from which it can be seen that for the case Z2 ^ -Z1 the total lengthZ = Z1-HZ2 is smaller than in the case Z1 = Z2. The ratio Z2IZ1 is therefore the decisive factor for the shortening. The use of a single surge in wave impedance only brings about a noticeable shortening with a very large ratio Z2IZ1, so that it is expedient to graduate several times, as shown in the basic circuit diagram of FIG. 3, where the wave resistances of the individual sections are Z1 to Z4. In Fig. 4 is shown as a schematic diagram of a double line in the manner of a Lecher line, in which the distance between the. Conductors 1,1 'is continuously increased towards the short-circuited line end and / or the diameter or the dimensions of the individual conductors 1,1' are reduced towards the short-circuited line end. This has the advantage of achieving a continuous tuning characteristic when tuning over the entire length, which in the case of wave resistance levels could only be achieved with a larger number of stages with finely graduated wave resistance jumps based on the required tuning range and the desired shortening. The pure change in dimensions to increase the wave resistance makes it possible to run the conductors 1, 1 'in parallel and still achieve the increase in wave resistance. By shifting the short-circuit bridge K, which can also be replaced by a capacitive short-circuit slide, a very wide frequency range can be covered in this way with a relatively small change in the geometric length; because due to the increase in wave resistance, the phase dimension of the line section is, so to speak, significantly increased compared to the case according to FIG. FIGS. 5 and 6 show exemplary embodiments of the subject matter of the invention. In Fig. 5 it is shown how a further reduction in the largest geometric dimension is achieved by the choice of the shape of the line section according to the invention. The line section 3, 3 ', for example a coaxial line section, is guided in the shape of a circular arc, with the inner conductor continuously tapering towards the short-circuited line end in order to achieve a uniform outer conductor diameter. In this case, the short-circuit slide K can be guided and operated via a movement device which engages the short-circuit slide K through a longitudinal slot in the jacket of the outer conductor 3. which are led out through the line end 4 and connected to a drive device. The circular shape is of particular benefit to this training, since it ensures a perfect change in length over a particularly large angular range. As lines can be used in the inventive arrangements not only conventional shielded double lines or coaxial lines, but as a line can be, for. B. also a ribbon line - this is a double line, the two conductors of which are in the form of a ribbon - or a so-called strip line - this is a double line, one conductor of which is formed by a metal plate, the other conductor in the form of a ribbon or round conductor at a small distance opposite - are used as long as these lines have an outer jacket (shielding jacket). Here, too, the increase in characteristic impedance can be brought about by changing the conductor dimensions and / or the mutual conductor spacing. In Fig. 6 an embodiment for a circular arc-shaped strip line is shown. Above a metallic plate 5 of circular shape, an approximately sickle-shaped strip conductor 6 is held at a uniform distance from the plate by means of supports 7 made of dielectric material. In the center of the circular area, an arm-like short-circuit slide 9 is attached to an axis of rotation 8, which creates a high-frequency short-circuit between the metal plate - which forms one conductor of the double line - and the sickle-shaped strip conductor - which forms the other conductor. By rotating the axis 8, the slide 9 can therefore be displaced along the line. On the other side of the metal plate 5, a further such double line can be provided in a manner known per se. If its tuning slide is rigidly connected to that of the first resonator via the axis or via a gear, this arrangement can, for example, advantageously be used as a two-circuit tunable filter, for which the coupling elements for coupling in and out and the coupling between the circles would have to be provided. An arrangement of this type with two resonance lines can also be used for an oscillator with a large tuning range, expediently in such a way that, for. B. for a grid base circuit, a resonator is used as the cathode circuit and the other is used as the anode circuit. This can easily be achieved with a disc tube that penetrates both circles perpendicular to the plane of the metal plate in the area of low wave resistance, that is to say in the area of the open line end 10. With an oscillator of this type with a metal plate diameter of 13 cm, a lowest wave impedance of around 40 Ω and a highest wave impedance of around 400 Ω, it was possible to tune through a range from around 150 to around 1500 MHz in oscillator mode. To avoid radiation, the ribbon cable is shielded with a hood - in the case of FIG. 6 with a box 11. Patent claims: 1. Tunable over a wide frequency range by means of a short-circuit slider, from unslotted Conductors existing, having an outer sheath, serving as a resonator line arrangement, their wave resistance in the area swept by the short-circuit slide towards the short-circuited line end increases abruptly or in a steady transition, according to patent 1015 873, characterized in,