DE3033674A1 - Waveguide with resonator using microstrip conductor - has coupling to exclusion band guide via loop or hole keeping max. excitation of dominant mode - Google Patents

Abstract

The waveguide has a resonator formed by coupling the guide to a microstrip conductor. The design produces a saving in space and weight as well as higher figures of merit than conventional designs. It has an improved tuning capacity. The waveguide is of the exclusion band type. The microstrip conductor is coupled to the exclusion band type waveguide via a loop coupling or a hole coupling. The shape, size and position of the coupling element is selected such that the dominant transverse electromagnetic mode is subjected to maximum excitation. The housing (5) of the strip conductor is physically linked to the waveguide.

Description

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Resonator arrangement The invention relates to an arrangement of a hollow conductor to which a microstrip line is coupled. Such groundings are e.g. used to build resonators.

State of the art Microstrip line technology: The most important technology for modern systems of radio relay and satellite radio is the microstrip line technology.

It makes it possible to use microwave integrated circuits cheaply and to be produced in large numbers. Some components like amplifiers, oscillators or filter elements can only be used in this technology because of the following disadvantages be implemented unfavorably: 1) circuit losses are relatively high, so that oscillators only have a low external quality factor.

2) The dielectric constant of the substrate material is from depending on the temperature.

3) Coordination options are difficult to implement.

From this z. B. derive the following unfavorable properties: 4) It is difficult to set a given frequency.

5) Long-term stability is poor. The temperature drift of the frequency is typically 10 / OC and is therefore around 1 to 3 orders of magnitude for almost all applications too high.

6) The short-term stability, i.e. H. the FM noise is similarly unsatisfactory.

i) The circuit losses are usually too high if the resonance circuit is used more strongly coupled in order to increase the quality factor.

8) Optimizing the circuit (e.g. for power adjustment) is cumbersome (and therefore no longer cheap). Because of the scattering of the semiconductor elements this process must be repeated for each element.

To compensate for these disadvantages, there have been essentially no problems so far pursued two solutions: The coupling of the circuit to a circular cylinder E010 resonator or a dielectric resonator. Both solutions are, however complex and therefore expensive.

Blocked-range waveguide technology: The circuit technology with waveguides below the cut-off frequency, usually called stop-band waveguide technology, became only developed in the last 12 years. First, Craven discovered / 1 / Wavegllide below cutoff: "A new type of microwave integrated circuitt? Microwave Journal, vol. 13 (Aug 1970), p. 51 the blocked-range waveguide as a new type of switching element, with which circuits can be built that in contrast to conventional circuits do not know wave propagation in microwave technology. This is then an integrated Subsystems can be set up without the need for connecting cables.

The first stage of development of the new circuit technology was almost shaped exclusively by Craven and his working group. The external features of the restricted range waveguide, its small volume and light weight exposed and exploited to bandpass filters for applications in satellite radio to realize. Such filters are used today by many device manufacturers.

The second and so far last development stage of this circuit technology was determined by the investigations of / 2 / SchOnemann, Knöchel, Begemann: "Components for microwave inteerated circuits with evanescent mode resonators ", IFEE Trans.

MTT, vol. MTT-25 (1977), pp. 1026-1032. One can be as you Summarize the result that all implemented circuit components with semiconductor devices in their electrical properties mostly those described in the literature so far The following are clearly superior: The advantages of circuit technology with waveguides underneath the cut-off frequency are summarized in the following: 1. The switching elements have concentrated character.

2. A switching element that has been implemented either acts only indtively or only capacitive. Its property is therefore relatively easy to predict.

3. There are no interfering parasitic switching elements.

4. The circuits are broadband and easily tunable.

5. The circuit losses are low.

6. Passive and active circuit components can be easily integrated will.

7. The microwave networks are distinguished by a remarkable simple structure.

8. The size, weight, and cost of circuits are significant lower than in normal waveguide technology.

The disadvantage is the complex and typical of waveguide technology thus expensive installation of semiconductor components.

The invention is based on the object of specifying an arrangement with which resonators can be built, which in addition to a simple, light, space-saving and weight-saving design also higher quality than stripline resonators and have better tunability.

The object is achieved as described in claim 1. The subclaims indicate advantageous further training.

In the following the invention is based on figures and exemplary embodiments explained in more detail.

FIG. 1 shows the coupling according to the invention of a microstrip line to a restricted area waveguide with a coupling loop a) to the waveguide wall (Wide or narrow side) and b) on the waveguide front side, where 1 means Blocked-range waveguide, 2 tuning screws, 3 coupling loops, 4 substrates and 5 stripline housings.

Figure 2 shows an arrangement according to the invention with hole coupling, 6 means tuning screw, 7 backside metallization, 8 housing, 9 substrate material, 10 track structure, 11 coupling hole.

Figure 3 shows an embodiment of a Gunn Cszil lators a) cross-section, b) plan view, where 12 means tuning screw, 13 means waveguide below the cutoff frequency, 124 coupling loop, 15 Gunn element, 16 stripline, 17 SMA socket.

The figure shows the tuning range of the Gunn oscillator.

Figure 5 shows an embodiment of an FET oscillator a) Schematic representation of the FET oscillator, b) Partial view of the FET VCO, here means 18 FET, 19 varactor.

FIG. 6a shows the mechanical tuning range of the FET oscillator.

FIG. 6b shows the electronic tuning characteristics of the FET-VCO, where Var is: varactor voltage The basic idea of this circuit technology is, the electrical advantages of the restricted-band waveguide technology with the economic Combine manufacturing processes of microstrip technology. This is supposed to the structure of the microstrip line (dielectric substrate with copper cladding in a:; ehäuse) are retained. However, resonators are no longer allowed the microstrip line, as its quality factor is suitable for an application in oscillators and amplifiers would be too low. Instead, the dimensions of the housing can be chosen so that there is a rectangular waveguide below the cutoff frequency represents. The microstrip line must then be used to build up resonance structures interrupt and the housing acting as an inductive blocked range waveguide through Complete the addition of the complementary energy store (e.g. tuning screw). Since, as in / 2 /; no parasitic switching elements capacitive Generated character, one can realize simple equivalent circuit diagrams unadulterated. This allows an ideal requirement for any circuit structure with this circuit technology to be fulfilled: One can do the tasks "Transformation of real and imaginary parts of the circuit impedance "independently of one another (i.e., separately) by the real part only via the shape of the microstrip line, the imaginary part only influenced by the housing added to the resonator. For the separation it is essential that that in this part of the circuit (the resonator) no wave propagation is possible is.

One works here with concentrated switching elements.

Realization options: The different versions differ This is essentially due to the way in which the stripline is coupled to the resonator. It is about loop and hole coupling, with shape, size and position the coupling elements the coupling strength can be changed.

a) Loop coupling The strip line opens into a restricted area hollow ter. At the point where it ends, the stripline ends with a loop that is attached to the H - field of the H10-l as well as on one of the two walls of the waveguide (Fig. 1>.

b) Hole coupling A Milled piece of restricted area waveguide. The backside metallization is about it located stripline forms the upper wall of the waveguide. The tuning screw is the capacity of the resonant circuit. The coupling to; the stripline circuit happens by means of holes in the rear side metallization of the substrate (Fig. ').

Properties In addition to the remarkable economic properties (simple, light, space and weight-saving and thus inexpensive construction) has this technique has a number of excellent electrical characteristics that make it a Interesting addition to the stripline technology distinguish: - Grades that urn are many times higher than with stripline resonators.

- Coupling factors can be set and changed in almost any way spreads only a little over wide frequency bands.

Networks are because of the quasi-concentrated character of the switching elements easy to design. Simple equivalent circuit diagrams are the result.

- Excellent tunability.

Application examples: With this technique, two oscillators were built, different types of coupling were examined in each case.

FIG. 3 shows the schematic view of a Gunn oscillator Der The resonance circuit is coupled to the Gunn element by a loop. The real part transformation happens via the tapered microstrip conductor. The operating behavior after still Figure 4 shows non-systematic optimization. Then the oscillation frequency Only detune over half of the X-band with the tuning screw, although the Power; fluctuates by 3 dB.

FT-szillator Figure 5 shows the structure of an FET oscillator. It was for sen FET 18 (in the strip line housing) a source circuit selected to maximum Get output power and ensure good heat dissipation. The feedback Loop between output (drain) and input (gate), which is necessary for the stability factor of the FET was designed as a transmission resonator with hole coupling.

The matching circuit of the FET as well as the shape and size of the coupling holes have been experimentally optimized to achieve maximum performance at the same time to get the largest possible tuning bandwidth.

A varactor 19, which was built into the gate circuit, he.

an electronic one was also possible after additional optimization Tuning the oscillator (Fig. 5b).

The following values were achieved (see Fig. 6): 1) Mechanically tunable Oscillator: - Center frequency f0 = 7.8 GHz - Tuning bandwidth: af = + 550 MHz ~ Power at f0: PO = 10 dBm - power fluctuation: AP = 1.2 dB - efficiency : 12.8% # # <29.6% (UDs = 3 V) 2) FET-VCO: - mechanical tuning range: f = 5.7: 5.80 GHz - electronic tuning range: at f0 = 5.70 GHz (p0 = 10.2 dBm): Af = + 1000 MHz, AP = + 1.8 dBm at f0 = 5.80 γHz (P0 = 12.4 4Bm):: = + 900 MHz, #P = - 1. dßm (UDS = 3 V) Blank page ropes

Claims (4)

Patent claims 0 arrangement of a waveguide to which a microstrip power is coupled, characterized in that the waveguide is a blocking range waveguide is that the fril krostreifenleitung via a loop coupling or via a Hole coupling to the restricted area waveguide is coupled that the shape, size and the position of the coupling elements is chosen so that an H10 wave is optimally excited is, and that the stripline housing is galvanically connected to the waveguide is. 2. Arrangement according to claim 1, characterized in that the microstrip line on the end face or the narrow side face or the wide side face of the restricted range waveguide is coupled. 3. Arrangement according to claim 1 and 2, characterized in that the Coupling loop as a continuation of the microstrip line in the same position as the loop is bent. 4. Arrangement according to claim 1, characterized in that the Blocked-range waveguide cut into the microstrip line housing as a groove is.