DE1054513B - Cavity resonator circuit - Google Patents

Description

GERMAN

In the high-frequency technology there is often the desire to have a frequency standard that is in a has consistent properties in a certain frequency range. As tunable and calibratable At very high frequencies, cavity resonators are normal because of their low internal losses suitable. In many cases it is desirable to have cavity resonators connected to continuous power lines (e.g. coaxial cables, waveguides) to be coupled in such a way that the resonance display is largely is frequency independent. Also, in many cases, there will be a constant bandwidth across the area required.

On the basis of the above conditions, equations can be set up, their solutions contain the conditions that such a resonator must meet.

In Fig. 1, the basic circuit diagram of such a resonator is shown. The voltage U ₀ is the output voltage, e.g. B. on a coaxial line or in a waveguide. A resonant circuit 1 is coupled via the coupling capacitance C _k , which consists of a fixed inductance and the two variable capacitors C1 and C 2 and is loaded by a resistor R (e.g. display diode) to which the voltage U _ii is applied.

In order to make the resonance display largely independent of frequency and an approximately constant one To maintain bandwidth over the entire range, the following conditions apply:

The resonance resistance of the circuit must increase quadratically with the resonance frequency fr , while the coupling capacitance Ck should decrease in inverse proportion to the square of fr .

One could use these conditions, e.g. B. in the circuit diagram of Fig. 1, meet in that Ck, Cl and C2 are set separately for each frequency. This process is technically useless. In the arrangement according to the invention, coordination of the circuit, coupling to the power line and transformation of the load resistance are combined in such a way that the calculated conditions are largely met for each resonance frequency.

There is now an arrangement with a cavity resonator is known in which by moving the galvanically with the wall of the resonator making contact tuning stamp at the same time the degree of coupling to a coupled line is changed. This results from the use of a stamp, the dimensions of which are in the order of magnitude of the Wavelength lie, inevitably two cavities that can come into resonance, with this inclination double resonance is still favored by the type of coupling, since the displacement

Applicant:

Pintsch Electro G. mb H.,
Constance (Lake Constance), Bücklestr. 3

Dr.-Ing. Hermann Ritzl, Hechendorf (Pilsensee) _r
has been named as the inventor

of the stamp to higher frequencies (smaller cavity) on the one hand the space behind the stamp is larger and thus also comes close to resonance, on the other hand a large part in this position the coupling opening is covered, so that the coupling with the space behind the stamp particularly grows big.

In the case of a cavity resonator circuit, the tuning element also has the coupling properties changed in a predetermined manner, a stamp is adjustable within the resonator according to the invention arranged, which loads the resonator capacitively and at the same time during an adjustment on the one hand the capacitive coupling of the resonator to an energy source so changed and on the other hand the Output voltage of the resonator due to capacitive loading of an operated in the aperiodic state Outcoupling line influenced in such a way that when the frequency-determining stamp is adjusted, the Resonanzwi the stand at the location of the stamp increases quadratically with the resonance frequency, while the coupling capacitance decreases in inverse proportion to the square of the resonance frequency.

An embodiment of the invention is explained in more detail with reference to FIG.

FIG. 2 shows a cut-open cavity resonator with a diode coupling 1 that has already been proposed elsewhere. The resonance tuning is done by an adjustable punch 2, which capacitively loads the resonator. The coupling to the power line 3 (for example waveguide) takes place through the opening 4, which is located directly below the tuning die 2 . By a suitable choice of the diameter of the opening and the ram it is achieved that the stray capacitance, via which the resonator is coupled to the line, changes as the ram approaches, so that with each

809 789/347

Claims (4)

Stamp position (i.e. resonance frequency) gives the required coupling capacitance. Furthermore, the tuning punch 2 is not located in the middle of the resonator, but at the entrance of the diode chamber 1. This ensures that the diode is coupled to different strengths depending on the position of the punch 2, since with increasing punch immersion depth the capacity of the aperiodic one State operated diode chamber grows and thereby the voltage maximum is shifted from the center of the resonator to the beginning of the diode chamber. The diode voltage increases with increasing capacitance, i. H. with decreasing frequency. As a result, the resonance resistance formed by the transformed diode resistance on the tuning ram increases with the square of the frequency with a simultaneous suitable choice of ram diameter and position in relation to the diode space. The arrangement according to the invention thus allows a cavity resonator to be tuned in such a way that both the bandwidth and the amplitude of the voltage drawn remain approximately constant over a very large range. In the case of a measured design sample, the desired conditions could largely be met in the entire area in which the resonator was unambiguous. The method according to the invention is of course not limited to the coupling of diodes to the cavity resonator. Any other display element (e.g. thermistors) can also be inserted into the coupling space, which according to an older proposal can be designed as an intermediate piece of a waveguide whose cut-off frequency is higher than the operating frequency of the circuit, with components being provided on the intermediate piece, which, as reactive resistances, influence the line replacement parameters of this waveguide section that determine the cut-off frequency and are mechanically adjustable with regard to their electrical effectiveness. But you can also add another power line, so that a loosely coupled, tunable filter with a constant bandwidth and constant output amplitude is created. Furthermore, there is the possibility of making the coupling space between the display element or the transition to the power line adjustable according to the earlier proposal mentioned, and a filter or wave meter with an adjustable, frequency-independent bandwidth and voltage is then obtained. Patent claims: 1. Cavity resonator circuit, whose tuning element at the same time the coupling properties in changed in a predetermined manner, characterized "that within" the resonator a stamp is arranged adjustable, which capacitively loads the resonator and at the same time during an adjustment on the one hand, the capacitive coupling of the resonator to an energy source is changed and on the other hand the output voltage of the resonator due to capacitive loading of an im aperiodic state operated decoupling is influenced in such a way that when adjusting the frequency-determining stamp with the square of the resonance resistance at the location of the stamp the resonance frequency increases, while the coupling capacitance is inversely proportional to the Square of the resonance frequency decreases. 2. Arrangement according to claim 1, characterized in that the coupling of the resonator to the generator via a coupling opening in a continuous power line. 3. Arrangement according to claim 1 or 2, characterized in that in the aperiodic State operated decoupling line a display element, z. B. a diode is located. 4. Arrangement according to claim 1, 2 or 3, characterized in that the frequency-determining Stamp itself outside the center of the resonator, especially near the decoupling line, is located. Considered publications:
U.S. Patent No. 2,524,532. 1 sheet of drawings © SOi 78Ϊ / 347 3.59