SU873316A1 - Counter-rod-mesh filter - Google Patents

Description

(54) MATCH-FIRST FILTER

I

The invention relates to frequency selective devices and can be used as a stand alone unit or as part of various microwave devices for selecting signals of a certain frequency range.

Known counter-rod microwave band-pass filter containing the input and output inverters, rod resonators and an additional shunt resonator in the form of a rod, mounted on one of the end walls of the filter GP.

However, the known interdigital filter has a low level of suppression of parasitic harmonics, an increase in which impairs matching at the fundamental frequency. This disadvantage is particularly pronounced with relatively wide bandwidths from 10 to 30%, while with bandwidths from 30 to 70%, there is almost no suppression.

The closest to the proposed is a counter-rod filter containing inverters, rod resonators, with one opposite ends of adjacent rod resonators grounded and others open, and the main open resonator, of length Do / 4p, fixed on one of the inverters at a distance Yao / 2n from its entrance G23

ten

However, in the known counter-rod filter, with relative passbands of 10-30%, the filtration quality deteriorates due to the fact that the level of the obstacle band remains

IS is constant, and the attenuation value at the harmonic frequency decreases. This is due to the fact that the half-wave directional coupler is formed by a narrow-band resonant segment,

20 the relative band of which does not exceed 10%.

Claims (2)

The aim of the invention is to expand the stopband and increase the 3 decay values to the harmonic frequency. To achieve the goal, the opposite rod filter containing inverters, rod resonators, with one opposite ends of adjacent rod resonators grounded and others open, and the main open resonator ig / 4n, fixed on one of the inverters at a distance from its input, was added an open resonator, of a length fixed on the same inverter on the opposite side at a distance from its input, and in said inverter, two cavities located symmetrically with respect to its axis and, in the common wall of which an adjustable communication window is made and in each band there is an open end, respectively, of the main and additional open resonators, and their opposite ends have a loop-like shape, where 1 o is the length of the working wave, n is the harmonic number. FIG. Figure 1 shows a counter rod filter with a partially removed side plate; general view; in fig. 2 is a section A-A in FIG. 3, in FIG. 3 - inverter, section along the axis of two cavities; in fig. 4 is a section BB in FIG. 3. Counter-rod filter contains inverters 1 and 2 and rod resonators 3-5, located; between the ground parallel side plates 6 and 7, fixed on the new 8 and 9. On one of the inverters, for example 1, fixed on the distance o / 2p from its input (1 o - the length of the working wave, n - harmonic number ) the main open resonator 10, the length of Poison / 4p, and on the opposite side of the same inverter, also on the Yao / 2p distance from its input, an additional open resonator 11, length 1o / 4p, is fixed. In the same inverter, two cylindrical cavities 12 and 13 are arranged symmetrically about its axis and have a common wall 14 in which an adjustable communication window 15 is made. Adjustment is carried out by means of a screw 16. In each cavity 12 and 13 there is an open end of the respective main 10 and an additional 11 open resonators, and their opposite ends, having 64 loop-like shapes, are brought out through the openings 17 and lie in a plane perpendicular to the side plates 6 and 7. The counter-pin filter works as follows shimm way. The filtration of signals of the required frequency range is carried out due to the resonant structure formed by rod-like resonators 3-5. The length of each rod-shaped resonator 3-5 is a quarter of the main working wave. It is known that the structure on the opposite quarter-wave rods has bandwidths on odd harmonics. To suppress the parasitic harmonics, they serve as the main 10 and additional 11 open resonators, which at the harmonic frequency at their junction with the inverter 1 create a short circuit. which harmonic current. The main 10 and additional 11 open resonators are coupled by a high-frequency electromagnetic field through the connection window 15 and form a notch filter. The inner conductors of this filter are the main and additional open resonators 10 and 11, and the outer conductors are the walls of the cylindrical cavities 12 and 13. The filter is excited by the loop-shaped form of the main and additional open resonators 10 and I. The pass band of the counter-rod filter is regulated by a screw 16 The main and additional open resonators 10 and 11 have two communication sites: the external one - between the ends of the loop-shaped form, the internal one - through the communication window 15. The external communication is not adjustable uemoy. The characteristic of the notch filter at the harmonic frequency of the counter-rod filter approaches the elliptical one due to the existence of two communication sites, which makes it possible to obtain an additional damping pole on the notch characteristic, and this improves filtering. Since the shorting of the harmonic currents is produced by a notch filter, the filtration of the counter-rod filter is improved by increasing the barrier bandwidth. In the proposed counter-rod filter, the barrier band is expanded and the attenuation at the harmonic frequency is increased. Claims. The counter-rod filter, the inverters, the core resonators, with one opposite ends of the adjacent core resonators grounded, and the others open and the main open resonator D-Ap length, fixed on one of the inverters at a distance X input, characterized in that, in order to broaden the obstacle band and increase damping at the harmonic frequency, an additional open resonator with a length of NF / AM, introduced on the opposite side of the inverter at the distance I (/ 2p from its inputs, and 66 in the specified inverter are two cavities located symmetrically about its axis, in the common wall of which an adjustable communication window is made and in each cavity there is an open end, respectively, of the main and additional open resonators, and their opposite ends are loop-shaped where working wave, n - harmonic number. Sources of information taken into account during the examination. Patent of Great Britain No. 1191984, cl. H I W, published, 1970. 2. USSR author's certificate 657484, cl. H 01 R 1/20, published. 1977 (prototype). -A S (fui.2 G6 W2.J