SU1091263A1 - Microwave band-pass filter - Google Patents

Abstract

MICROWAVE BAND FILTER, containing rectangular substrate made of non-magnetic material, on one side of which is placed the first ferrite film, the input-pus converter placed on the first ferrite film, and the output converter, characterized in that, in order to increase the selectivity, . a second ferrite film is inserted in it, which is placed on the other surface of the rectangular substrate, with both surfaces of the rectangular substrate being made polished, the height of the rectangular substrate chosen equal to 4. where. Vg is the propagation velocity of the acoustic wave; f is the center frequency in the passband of the filter; (f) p is an integer, and the output transducer is placed on the second ferrite film.

Description

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The invention relates to microwave radio technology and can be used in radio devices as a filter for signal selection and processing.

A known microwave pass filter for magnetostatic waves containing a rectangular substrate of a nonmagnetic material and a ferrite film on which the input and output transducers of a magnetostatic wave into an electromagnetic wave with I1 are placed. However, the specified microwave filter is characterized by a low quality factor, i.e. poor frequency selectivity of the input microwave signal.

The closest to the proposed / is a pass-through microwave filter at magnetostatic waves, containing a rectangular substrate made of a nonmagnetic material. On one side of which is a first ferrite film, an input transducer placed on the first ferrite film, and an output transducer. Input and output converters are made in the form of a grid of counter pins 2.

However, the known device does not provide sufficient frequency selectivity of the input signal.

The purpose of the invention is to increase the selectivity.

The goal is achieved in a microwave pass-band filter containing a rectangular tube: a nonmagnetic material, on one side of which a first ferrite film is placed, an input transducer placed on the first ferrite film, and an output transducer, the second ferrite is inserted into it the film, which is placed on the other side of the rectangular Podolski, while both surfaces of the rectangular substrate are made polished, the height of the rectangular substrate is chosen equal to

.avc - propagation speed

acoustic wave; 55 f is the center frequency in the passband of the filter; n is an integer

and the output} converter is located on the second ferrite foam.

The drawing shows the design of a microwave pass filter.

The band pass microwave filter contains the first ferrite film 1 located on. one side of a rectangular substrate 2 made of a non-magnetic material. This may be, for example, an epitaxial film of an iron yttrium garnet (GTT) on the surfaces of a rectangular substrate of gallium-gadolinium garnet (YYY). An input transducer 3 of an electromagnetic wave into a magnetostatic is placed on the first ferrite film, On another surface rectangular substrate. The second ferrite film 4 is located, on which the output transducer 5 is placed. The input transducer 3 and the output transducer 5 of magnetostatic waves are made in the form of meanders, tuned to the frequency band in the passband of the filter.

The height d of the rectangular substrate 2 is selected from

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d

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at the same time d L ,, where L is the Bolny length magng-1 static oscillations, n is an integer, a number.

When using as a material a rectangular substrate 2 gallons, 17.nigadoli.t: 1 eu garnet, the velocity pc of spacing; 1 transverse acoustic wave V, 3.5 cm / s, for an operating frequency f. 1 GHz and n 200 the required thickness of the rectangular substrate is 2 d 357 microns.

The filter works as follows

A rectangular substrate 2 with the first and second ferrite films 1 and 4, the input and output converters 3 and 5 of magnetostatic waves are placed in a magnetic field H, which is oriented perpendicular to the plane of the first and second ferrite films I and 4. To the input transducer 3 in the first ferrite section GC.I, I receive a volume magnetostatic wave in the frequency band determined by the period of the transducer 3. The wave propagates in r; brittle ferrite film and, due to the magnetostriction effect, creates an elastic e acoustic waves in the material of the rectangular substrate 2 which propagate in a direction and at a speed of magnetostatic wave. An acoustic wave propagating in the material of the rectangular substrate 2 excites a second ferrite film 4 with a magnetostatic wave, which in the output converter 5 is converted into a microwave signal. If the frequency f at a given height of the rectangular substrate 2, defined by the ratio (1), does not correspond to the value of d, then acoustic waves are not excited in the volume of the rectangular substrate 2. The height of the rectangular substrate 2 is chosen many times greater than the length waves of magnetostatic oscillations so that magnetostatic waves excited by an input transducer on one surface of a rectangular substrate 2 do not excite an output transducer 5. Since the wave attenuation occurs in exp (cl L / D I times, at d 200 μm and / 20 μm, weakening the amplitude of the magnetostatic wave occurs by a factor of 10. Then the device will operate as a frequency filter, passing a signal with a frequency fp, and the amplitude-frequency characteristic of the device with square wave input and output converters will contain only one peak corresponding to the frequency f. and output 5 transducers are single-ended transducers, then the amplitude-frequency response will contain a series of narrow bandwidths that are multiple to f „. The use of the SECH transmittance filter compared to the known filters on ferrite spheres will increase the frequency selectivity by at least 10 times, has a planar design and can be used as an element of microwave integrated circuits.

Claims (1)

Microwave bandpass filter containing a rectangular substrate made of non-magnetic material, on one side of which a first ferrite film is placed, an input converter placed on the first ferrite film, and an output converter, distinguishing * with the fact that, in order to increase selectivity, a second ferrite film is inserted into it, which is placed on another surface of the rectangular substrate, while both surfaces of the rectangular substrate are polished, the height of the rectangular substrate is selected and equal to where, Vg is the acoustic wave propagation velocity; f is the center frequency in the passband of the filter; η is an integer, and the output converter is placed on a second ferrite film. N0 oo 109