DE4123769C2 - Harmonic oscillator for the millimeter wave range - Google Patents

Description

The invention relates to a harmonic oscillator for the millimeter wave range according to the preamble of Pa Such a harmonic oscillator is at already known for example from DE 35 44 912 A1.

The well-known and passive stabili at a fixed frequency The harmonic oscillator consists of a height reduction adorned waveguide, in which a semiconductor diode be finds and at one end a coupling waveguide for the harmonic is connected. To the other end of the reduced-height waveguide is a waveguide cut connected in which the fundamental wave  is spreadable. This waveguide section is in one first and a second spacer divided between which has a resonance panel inserted, which is the reason wave passes and the harmonic reflects. To the free end of this waveguide section is over a Kop pelschlitz a high quality cavity resonator for the reason shaft connected, the ge in terms of installation volume takes up as much space as the rest of the Oszilla gate arrangement.

To tune the semiconductor diode to the frequency of the Fundamental wave is a quasi-ko in the known oscillator axial circuit structure provided, such as as already known from DE 32 39 499 A1.

The structure consists of a metallic circular disc and a short connecting line, which has an except Band stop filter arranged half of the inside of the waveguide (Blocking filter) connected to a DC power supply is. Together with the parasitic elements of the half lead terdiode this circuit structure forms a quasi-ko axial resonator for the frequency of the fundamental wave. In the The frequency of the harmonic is affected by the metallic circular disc as a quasi-radial wave transformer that can handle the high Wave resistance of the waveguide to the low source adapts to the diode.

The output power of the harmonic is in the known Harmonic oscillator affected by the length of the first Spacer and thus by the position of the resonance cover. To optimize the oscillator, you must first this length can be optimized by replacing the cavity  resonators a short circuit plate is attached. On finally the length of the second spacer is varied until the resonator engages the "oscillator".

In addition, it is from Jean von Bladel: "Dielectric resonator in a waveguide below cutoff ", in IEEE Transactions on Microwave theory and techniques, Vol. MTT- 29, No. 4, April 1981, pages 314-322 to arrange dielectric resonator in a waveguide, which is operated at its base frequency.

It is also from Albert D. Helfrick: "Voltage controlled oscillator uses ceramic resonators "in ham radio, June 1985, pages 18-26, known, a voltage controlled Oscillator through a ceramic resonator too stabilize.

The object of the invention is to create an overhang to create lenoszillator of the type mentioned installation volume is as small as possible and that on simple can be optimized in a way that was previously possible was.

This problem is solved by the in the characteristic Part of claim 1 specified features. Advantage sticky refinements and / or further training are the Removable subclaims.

The solution according to the invention provides that in a waiter wave oscillator for the microwave range with a Semiconductor diode in a waveguide in which due cross-sectional dimensions do not spread the fundamental wave  is capable and one end for decoupling the Harmonic is provided and at the other end High quality resonator is arranged for the fundamental wave the resonator is slidably arranged in the waveguide neter dielectric resonator.

A major advantage of the invention is that now by simply moving the resonator in Waveguide over the ape towards the ends of the waveguide periodically decaying field of the fundamental wave in the waveguide any coupling continuously between coupling 0 (larger Distance between dielectric resonator and diode) and somewhat more than critical coupling (small distance between  dielectric resonator and diode) that can.

Another advantage is that the installation volume the overall arrangement is much less than that a comparable harmonic oscillator, which with a Cavity resonator is equipped because the dimensions of the dielectric resonators are always smaller than the Ab measurements of the waveguide into which the resonator is inserted is brought.

Another advantage is that the fre source-selective coupling of the dielectric resonator also so-called "overmoded dielectric resonators" (i.e. dielectric resonators with multiple possible operating frequencies) can be used as a strong coupling mainly only at one of the possible frequencies is achieved while the coupling with the other Fre sequences is usually negligibly weak. Reference Lich these resonators with the Os invention zillator arrangement thus an additional filter effect achieved.

In an advantageous embodiment of the invention free end of the waveguide on the resonator side with a stu closed feniform absorber, the stu fen are dimensioned so that any existing An parts of the fundamental wave are absorbed by the absorber, however, the spread of the harmonic is not disturbed. Instead of the step-shaped absorber also a correspondingly positioned short circuit plate be seen.  

In a development of the invention, the free end is which is provided for decoupling the harmonic, with egg Nem separate coupling waveguide connected, the cross section dimensions are dimensioned so that the fundamental is not capable of spreading in it, however the Harmonic.

In the following, the invention will be explained in more detail with reference to the figures explained. Show it:

Fig. 1 shows a first preferred embodiment of to the invention OF INVENTION harmonic oscillator for the 90 GHz range,

Fig. 2 shows a second preferred embodiment of to the invention OF INVENTION harmonic oscillator for the 90 GHz range,

Fig. 3 shows a third preferred embodiment of the inventive harmonic oscillator for the 90 GHz range.

The harmonic oscillator in Fig. 1 consists of four main parts:

• a) the Os zillator holder known per se from DE 35 44 912 A1 with the semiconductor diode 4 (eg gun diode), the quasi-coaxial circuit structure consisting of a metallic circular disk 5 and a short connecting line 6 , the blocking filter 7 , the direct current supply 14 ( which is electrically isolated from the waveguide housing by a Teflon insulation 13 ) and the height-reduced Q-band waveguide (40-60 GHz) 2 b and a ver slidable heat sink 11 for the diode 4 with diode flange and a screw 12 for moving the Heat sink;
• b) the W-band coupling-out waveguide 8 (75-110 GHz), in which the harmonic wave (s), but not the fundamental wave, is (are) capable of propagation and which therefore has the effect of a high pass with respect to the fundamental wave;
• c) the W-band waveguide 2 a, which contains the dielectric resonator 1 , which is slidably disposed therein, and a step-shaped absorber 9 (for the fundamental wave);
• d) the Q-band waveguide intermediate piece 3 , in which the fundamental wave is capable of propagation and which connects the height-reduced Q-band waveguide 2 b of the oscillator gate holder to the W-band waveguide containing the dielectric resonator 1 .

The diode 4 is mounted in the reduced-height Q-band waveguide 2 b on the diode flange of the heat sink 11 . About the blocking filter 7 and the quasi-coaxial circuit structure 5 , 6 their DC voltage is supplied. At the frequency f _{o of} the fundamental wave, the metallic circular disk 5 of the quasi-coaxial circuit structure 5 , 6 acts as a capacitor, while the short connecting line 6 acts as an inductor. Together with the parasitic elements of the diode 4 , the disk 5 and the connecting line 6 form a quasi-coaxial resonator (QCR), the resonance frequency of which is somewhat higher than the operating frequency (target frequency) of the oscillator.

At the harmonic 2 f _{o of} the frequency f _{o of} the fundamental wave, the metallic circular disk acts as a quasi-radial wave transformer ("radial λ / 4 transformer") with a high transformation ratio. The diameter and the length of the short connecting line 6 to the notch filter 7 (band stop filter) also influences this transformation ratio and must be optimized in order to achieve maximum output power at the frequency 2 f _{o of} the harmonic.

The height-reduced Q-band waveguide 2 b (including the Q-band spacer waveguide 3 ) is connected to the two ends of the two with one of the two W-band waveguides 8 and 2 a, which is used for the frequency of the fundamental wave Look high fun. Since they also act as inductive terminations, the frequency f _{o of} the fundamental wave is also influenced by the length of the height-reduced Q-band waveguide 2 b and the Q-band intermediate piece waveguide 3 and must therefore be matched to the frequency of the QCR .

Since the W-band waveguide 2 a acts as a high-pass filter for the frequency of the fundamental wave, the magnetic field of the fundamental wave in it decays aperiodically towards the free end (depending on the distance to the diode 4 ).

In order to couple the dielectric resonator 1 critically, this is to be oriented in the waveguide 2 a in such a way that a magnetic coupling takes place, and then to be pushed in the direction of the Q-band intermediate waveguide 3 until the return loss for the frequency of the Fundamental wave is maximum. The step-shaped absorber 9 has the task of absorbing the part of the fundamental wave passing through the dielectric resonator 1 . With this arrangement, return losses greater than 20 dB can easily be achieved, which results in a strong coupling between the dielectric resonator 1 and QCR.

The phase required to stabilize the oscillator frequency is set by optimizing the distance between dielectric resonator 1 and QCR (with critical coupling) by varying the length of the intermediate waveguide 3 .

The following should be noted regarding the frequency stability of the oscillator notice:

The susceptibility as a function of the frequency difference of the QCR or the dielectric resonator 1 (which are connected in parallel in the electrical equivalent circuit diagram) of the operating frequency results in curves whose slope at the frequency difference zero is directly proportional to the quality of the corresponding resonator. One of the conditions for the oscillator to oscillate is that the sum of the imaginary parts of the admittance is zero. That means in this case that when the frequency of the QCR changes, the frequency is also changed at which the sum of the imaginary parts of the admittance is zero, but that the resultant frequency change of the stabilized oscillator is less than the frequency change of the QCR alone. It can be shown that the following relationships apply:

(Δf _OSC - Δf _STAB ). Q _QCR = Δf _STAB . Q _DR (1)

or

where Δf _STAB or Δf _{OSC is} the frequency difference of the stabilized or free-running oscillator from the operating frequency (set frequency) and Q _DR or Q _{QCR is} the quality of the dielectric resonator 1 or the QCR's. R is the reduction factor achieved by stabilization.

To compensate for the changes in temperature The frequency changes of the oscillator are as follows to note:

If one assumes that the free-running oscillator has a temperature coefficient normalized to the oscillator frequency f _OSC (Δf _OSC / Δϑ). / f _OSC (Δϑ is the temperature change), this coefficient for the stabilized oscillator is reduced by the factor R, so that in the event of a complete compensation of the temperature changes caused by temperature changes of the oscillator, by a suitable choice of the material of the dielectric Resonators for the normalized temperature coefficient of the material of the dielectric resonator 1 (Δf _DR / Δϑ) / f _{OSC the} following relationship must be met:

(Δf _DR / Δϑ) / f _OSC = -R. (Δf _OSC / Δϑ). / f _OSC (3)

To reduce phase noise through stabilization the following should be noted:

Since the phase noise is proportional to the mean value of the frequency change Δf due, the improvement in the noise-to-carrier signal ratio N / C is proportional to (Δf _STAB / Δf _OSC ) ² = R ² .

1 of the harmonic oscillator shown in Fig. 2 differs from the oscillator shown in FIG. Only in that the oscillator W-band waveguide now contains consistently 2 or 8 (the intermediate piece waveguide 3 in Fig. 1 is shown in Fig. 2 thus omitted and the height-reduced Q-band waveguide 2 b is replaced in FIG. 2 by a W-band waveguide), so that reference can be made to the description of FIG. 1 with regard to the explanation of the reference characters of the parts corresponding in the figures.

In this embodiment, the diode 4 is located in a waveguide 2 that works for the frequency of the fundamental wave in the blocking mode. The resonator for the frequency of the fundamental wave is again formed from the metal circular disk 5 acting as a capacitance and the short connecting line 6 acting as an inductor from the blocking filter 7 to the circular disk 5 and from the parasitic elements of the diode 4 (QCR). The dielectric resonator 1 serves here as an additional stabilizing resonator.

The harmonic oscillator shown in Fig. 3 differs from the harmonic oscillator shown in Fig. 2 in that in place of the metallic circular disc 5 and the Verbin dung line now a zylindischer pin 10 is provided (with no self-resonant) 6 (Fig. 2), so that with respect to the explanation of the reference numerals of the parts corresponding in the figures can be referred to the description of FIGS. 1 and 2.

In this embodiment of the oscillator, too, a W-band waveguide 2 or 8 is commonly provided, so that the diode 4 is located in a waveguide 2 operating in blocking mode at the frequency of the fundamental wave.

The diode 4 is magnetically coupled to the hollow conductor 2 by the pin 10 . The dielectric resonator 1 is the sole resonator for the fundamental wave here. By pushing the resonator 1 to the diode 4 , the desired coupling is produced. The pin 10 has before geous enough a diameter that is the same or approximately equal to half the wavelength of the radial harmonic.

It is understood that the invention is not limited to the The previous embodiments is limited, but entirely general for harmonic oscillators in millimeter waves area can be used (especially with others Frequencies).

Claims (11)

1. harmonic oscillator for the millimeter wave range, with a semiconductor diode in a waveguide, in which, due to its cross-sectional dimensions, the fundamental wave is not capable of propagation and one end of which is provided for decoupling the harmonic wave and at the other end of which a high-quality resonator for the fundamental wave is arranged is characterized in that the resonator is a dielectric resonator ( 1 ) slidably arranged in the waveguide ( 2 ; 2 a). 2. Harmonic oscillator according to claim 1, characterized in that the other end of the waveguide ( 2 ) with egg ner short-circuit plate or with a step-shaped ausgebil Deten absorber ( 9 ) is closed. 3. harmonic oscillator according to one of claims 1 or 2, characterized in that the one end of the Hohllei age ( 2 ) with a coupling waveguide ( 8 ) for the upper shaft is connected. 4. harmonic oscillator according to one of the preceding claims, characterized in that the semiconductor diode ( 4 ) via a pin ( 10 ) is magnetically coupled to the waveguide ( 2 ). 5. harmonic oscillator according to claim 4, characterized in that the pin ( 10 ) via an outside of the waveguide ( 2 ) arranged blocking filter ( 7 ) is connected to a DC supply. 6. Harmonic oscillator according to one of claims 4 or 5, characterized in that the pin ( 10 ) is zylinderför shaped with a diameter corresponding to half or at least approximately half the wavelength of the radial harmonic. 7. harmonic oscillator according to one of claims 1 to 3, characterized in that the diode ( 4 ) via a metallic circular disc ( 5 ), a short connecting line ( 6 ) and an outside of the waveguide ( 2 ) arranged blocking filter ( 7 ) with a DC supply is connected and that the parasitic elements of the semiconductor diode ( 4 ) together with the metallic circular disk ( 5 ) and the short connecting line ( 6 ) form a quasi-coaxial resonator for the fundamental wave and the metallic circular disk ( 5 ) as a quasi-radial wave transformer works for the harmonic. 8. harmonic oscillator according to claim 7, characterized in that the waveguide ( 2 ) is divided into two by a hollow conductor intermediate piece ( 3 ) interconnected parts ( 2 a, 2 b) that in the first part ( 2 a) the di electric resonator ( 1 ) is arranged and in the other part ( 2 b) the semiconductor diode ( 4 ), the metallic circular disc ( 5 ) and the short connecting line ( 6 ) and that in the waveguide intermediate piece due to its cross-sectional dimensions Fundamental wave is capable of spreading. 9. harmonic oscillator according to claim 8, characterized in that the first part ( 2 a) of the waveguide ( 2 ) is a waveguide for the harmonic, preferably a W-band waveguide, that the second part ( 2 b) of the waveguide ( 2 ) is a height-reduced waveguide for the fundamental wave, preferably a height-reduced Q-band waveguide, in which the fundamental wave is not capable of propagation due to the height reduction, and that the waveguide intermediate piece ( 3 ) is preferably a Q-band waveguide. 10. Harmonic oscillator according to one of the preceding claims, characterized in that for the compensation of the frequency changes of the oscillator caused by temperature changes, the material of the di electric resonator ( 1 ) according to the equation
(Δf _OR / Δϑ). f _OSC = -R. (Δf _OSC / Δϑ). f _OSC
compared to the normalized temperature coefficient (Δf _OSC / Δϑ). f _{OSC of} the oscillator is a normalized temperature coefficient (Δf _DR / Δϑ) that is reduced by an amount by a reduction factor R and provided with an opposite sign. f has _OSC . 11. Harmonic oscillator according to claim 10 with a composed of the parasitic elements of the semiconductor diode ( 4 ), the metallic circular disc ( 5 ) and the short connecting line ( 6 ) composed quasi-coaxial resonator for the fundamental wave, characterized in that the reduction factor R according to the equation
R = (1 + Q _DR / Q _QCR )
from the quality Q _{DR of} the dielectric resonator ( 1 ) and the quality Q _{QCR of} the quasi-coaxial resonator ( 4 , 5 , 6 ).