ES2215503T3 - MULTISECTION BAND PASS FILTER OF RESONANT CAVITIES. - Google Patents

Abstract

Multi-section band pass filter of resonant cavities (A1 to A6) coupled to each other, of which at least two non-successive resonant cavities (A2, A5) in relation to AF are engaged in counter-reaction through a conduit (21) which penetrates the two resonant cavities, the resonant cavities (A1 to A6) being arranged such that at least the resonant cavities to be engaged in counter-reaction (A2, A5) are located in an adjacent position, characterized in that the conduit (21) is configured as a loop that penetrates one of the resonant cavities and that crosses a groove (41) configured in the separation wall (40) of the adjacent resonant cavities and joins with a male (22) in the other resonant cavity (A5 ), and because the depth of penetration of the conduit (21) that includes the loop and the male is modifiable.

Description

Multi-section cavity bandpass filter resonant

The invention relates to a pass filter of multi-section band of resonant cavities coupled to each other, of which at least two non-successive resonant cavities in relationship with the AF are coupled in counter reaction through a conduction that penetrates the two resonant cavities.

Bandpass filters are already known for this kind. By coupling in counterreaction of cavities non-successive resonants in relation to AF increases the inclination of the flanks of the passing curve and, consequently, the selectivity of the bandpass filter is increased. In this context you have to keep in mind that the filter pass curve it shows minimum attenuation in the frequency blocking zone lower and upper (the so-called CAUER feature), while the pass curve of the band pass filters does not counter-coupled trailers show attenuation development monotonous growth towards the lower blocking areas and top (TSCHEBYSCHEFF feature). In the pass filters of multisection band coupled in counterreaction according to the current state of the art, the resonant cavities to be coupled in counter-reaction are linked through a coaxial conduction whose inner conductor forms an inductive loop that penetrates the area short-circuit or peak current area of the cavity corresponding resonant, to decouple and couple the AF in the two resonant cavities attached. The degree of coupling in counterreaction is determined by the surface size of corresponding loop, because the larger this one is the greater the field magnetic enclosed by the loop and with it the amplitude of the wave overcoupled To obtain the necessary phase rotation of 180º, The mechanical length of the coaxial cable is chosen such that the electrical length equals λ / 2 or an odd multiple of is. However, bandpass filters docked in Counterreaction of this type are not usable for older AF powers, since, as the coaxial cable is shorted in its initial part and its final part because of the loops, a standing wave is formed along the cable, so that at least one place of the cable produces a maximum of pronounced current.

The document DE-A-2 161 792, unveils a multi-section bandpass filter of resonant cavities coupled together, of which at least two resonant cavities non-successive in relation to the AF are coupled in counter-reaction through a conduction that penetrates the two resonant cavities (capacitive pin couplings C_ {1-4} and C_ {4.7}), and the resonant cavities are arranged in such a way that at least the cavities resonants to be engaged in counter reaction are placed in position adjacent.

The document EP-A-101 369 discloses a filter multi-section cavity with dielectric resonators and a counter-coupling in the form of a conduction that crosses a groove in the separation wall and produces the same inductive and capacitive coupling time.

The invention aims to provide a filter bandwidth of the type mentioned in the introduction of a fixed power counter-coupling.

This objective is met according to the invention. by a filter according to claim.

This avoids the coaxial cable that is extends outside the filter and carries the AF power coupled in counter reaction, and the heating problem involved. In instead, the conduit is reduced to a loop, which produces a inductive coupling, and a male, which produces a coupling capacitive The transition between inductive coupling and the capacitive coupling produces phase rotation at the same time 180º necessary. However, a precondition for this type counter-coupling is that the cavities resonants to be coupled in counter reaction must be located in mechanically adjacent positions. In general, this can be easily achieved by a U-shaped arrangement of the resonant cavities

The penetration depth of the conduction in The two resonant cavities are adjustable. This allows you to adjust the degree of counter-coupling coupling, on the one hand, and modify easily the degree of coupling in counter-reaction in case of Change the frequency tuning of the filter, for another. In both cases, this proposal has the advantage that, if the filter is tuned to a different frequency, the magnitudes of the inductive and capacitive coupling vary in the same way. By example, if the filter is tuned in a known way to a lower center frequency and counterreaction coupling of the corresponding resonant cavities must remain constant, for this the surface of the loop that It penetrates one of the resonant cavities. This takes place expanding the depth of penetration of the conduction. With this the male that produces the capacitive coupling also moves in the other resonant cavity. Since at the same time it has increased the penetration depth of the inner conductor of this resonant cavity for tuning at the lower frequency desired, the capacitive coupling remains constant. By consequently, counter-coupling is effective in a wide range of frequencies

An example of embodiment of a bandpass filter according to the invention simplified schematically. The drawings show:

- Figure 1: The bandpass filter in section along line A-A in figure 2.

- Figure 2: A plan view of the filter band pass

The bandpass filter includes six cavities resonators in the form of resonators A1 to A6 arranged in a U-shape. The AF is coupled to the first resonator A1 through connection 1 and decoupled from resonator A6 through connection 2. The successive resonators in relation to AF are coupled to each other in a manner known per se through bridges 3, which can only be see in figure 2, whose depth of penetration into corresponding resonators can be modified to adjust the degree of coupling and that can be fixed using screws clamping 4. The penetration depth can also be adjusted of the inner resonator conductors for tuning frequency. To do this, as shown in the section in Figure 1, the internal resonator conductors consist of a fixed part 11 and a piece 12 in contact with it and telescopically guided in the same, which can be moved by a bar 13 fixed by a clamping screw 14.

Because of the U-shaped mechanical arrangement of resonators A1 to A6, resonators A1 and A6, as well as A2 and A5, which are not successive in relation to AF, are located at mechanically adjacent positions. The A2 and A5 resonators are counter-coupled coupled in relation to the AF according to the present proposal To do this, the resonator A2 penetrates a conduction 21 which, on the one hand, forms a conduction loop in the A2 resonator in the short circuit zone or the current zone of crest near the wall and, on the other, crosses the wall of common separation of these two resonators through a slot 41 and ends up forming a male 22 on the resonator A5. Through this arrangement inductively decoupled resonator AF energy A2 and capacitively coupled, and therefore with a rotation 180º phase to achieve counterreaction coupling desired, on resonator A5. The penetration depth of the conduction 21 can be modified by bar 23. Conduction can be fixed using the clamping screw 24 in the depth of regulated penetration.

Claims (1)

1. Multi-section band pass filter of resonant cavities (A1 to A6) coupled to each other, of which at least two non-successive resonant cavities (A2, A5) in relation to the AF are engaged in counter-reaction through a conduit ( 21) that penetrates the two resonant cavities, the resonant cavities (A1 to A6) being arranged such that at least the resonant cavities to be engaged in counter-reaction (A2, A5) are located in an adjacent position, characterized in that the conduction (21 ) is configured as a loop that penetrates one of the resonant cavities and that crosses a groove (41) configured in the separation wall (40) of the adjacent resonant cavities and joins with a male (22) in the other resonant cavity (A5), and because the depth of penetration of the conduit (21) that includes the loop and the male is modifiable.