RU79718U1 - MICROWAVE MICROWAVE BAND FILTER FILTER - Google Patents

Abstract

The utility model relates to microwave technology, namely, microstrip microwave pass-band filters that are used to filter useful and suppress spurious signals in microwave devices.

A microstrip microwave bandpass filter is a dielectric substrate with a grounded metallized base on one side and microstrip conductors forming hairpin resonators on the other. Resonators are arranged in series and interconnected. One end of each resonator is free, and the other is short-circuited. The input and output of the filter are connected to the first and last resonators. In addition, two microstrip conductors are applied. One end of the first conductor is connected to the middle of the first resonator, and the second end is free. One end of the second conductor is connected to the middle of the last resonator, and the second end is free.

Additional microstrip conductors form notches tuned to the frequencies of the third harmonic spurious passband, which allows you to confidently suppress signals in the third harmonic spurious passband, and thereby improve out-of-band signal suppression and exclude the notch filter from the microwave circuit.

Description

The utility model relates to microwave technology, namely, microstrip microwave pass-band filters that are used to filter useful and suppress spurious signals in microwave devices.

The main areas of application of bandpass filters are microwave transmitting and receiving devices for:

- radio relay and satellite communication systems,

- radar stations,

- etc.

Known band-pass filters [1, 2] containing resonators. The length of each filter cavity is equal to a quarter of the wavelength at the middle frequency of the passband. One end of the resonator is shorted, and the other is open. The connection between the resonators is due to the edge fields between adjacent parts of the resonators. The input and output of the filter are connected to the first and last resonators.

These filters allow you to pass useful signals at frequencies in the passband of the filter with low loss and suppress signals outside the passband of the filter. However, due to the fact that the cavity length is a quarter of the wavelength of the useful signals, the signal suppression in the spurious passband of the third harmonic is significantly degraded. This degrades filter performance such as out-of-band signal suppression.

The closest technical solution is a band-pass filter on quarter-wave resonators [3].

The filter contains a dielectric substrate, on one side of which a grounded metallized base is applied, and microstrip conductors forming quarter-wave resonators are deposited on the other. Resonators are arranged in series and interconnected. One end of the resonators is free, and the other is short-circuited. The input and output of the filter are connected to the first and last resonators. The filter topology is shown in FIG.

This filter, like the analogs described above, allows you to pass useful signals at frequencies in the passband of the filter with low losses and suppress signals outside the passband of the filter, but suppression of signals outside the passband is provided by excluding third-harmonic spurious passband signals.

The technical result of the proposed bandpass filter is to improve out-of-band signal suppression, including spurious third-harmonic passband.

The proposed microstrip microwave bandpass filter is a dielectric substrate, on one side of which is grounded a metallized base, and on the other microstrip conductors are applied, forming hairpin resonators. Resonators are arranged in series and interconnected. One end of each resonator is free, and the other is short-circuited. The input and output of the filter are connected to the first and last resonators. Additionally, two microstrip conductors are applied, which form the notch tuned to the frequency of the parasitic passband of the third harmonic. One end of the first conductor is connected to the middle of the first resonator, and the second end is free. One end of the second conductor is connected to the middle of the last resonator, and the second end is free.

The technical result of this proposal is achieved by the fact that additional microstrip conductors form notches tuned to the frequencies of the spurious passband of the third harmonic, which allows you to reliably suppress signals in the spurious passband of the third harmonic, thereby improving the technical characteristics of the filter as out-of-band signal suppression

The essence of the proposed filter is illustrated by drawings.

Figure 1 shows the topology of the filter prototype.

Figure 2 shows the topology of the proposed drink-through filter.

Figure 3 shows the amplitude-frequency characteristic of a band-pass filter - analog

Figure 4 shows the amplitude-frequency characteristic of the proposed band-pass filter.

The proposed band-pass filter contains a dielectric substrate 1, on one side of which a grounded metallized base 2 is applied, and microstrip conductors are applied on the other side, forming successively located and interconnected resonators 3, 4, and 5, one end of each is short-circuited, and the other is free. The input of the filter 6 is connected to the first resonator, and the output of the filter 7 is connected to the last resonator. The length of the intermediate resonators of the filter is equal to a quarter of the wavelength at the average frequency of the passband. The coupling between the resonators is due to the edge fields between adjacent resonators. An additional microstrip conductor 8 is connected at one end to the middle of the first resonator 3, and its second end is free. Optional microstrip conductor 9 one end

connected to the middle of the last resonator 5, and its second end is free.

The filter works as follows. An input signal containing useful signals in the passband of the filter and spurious signals outside the passband is fed to the input of the filter 6 connected to the first resonator 3. The useful input signal in the passband of the filter passes from the input of the filter 6 through resonators 3, 4 connected to each other, 5 to the output of the filter 7. Spurious signals outside the passband, with the exception of signals in the spurious passband of the third harmonic, are reflected from the input of the filter 6 due to the frequency-selective properties of the filter. The signals in the parasitic passband of the third harmonic are suppressed and do not pass to the output of the filter due to notches, which are formed by additional microstrip conductors 8 and 9.

Comparison of the amplitude-frequency characteristics of the pass-through filter prototype and the amplitude-frequency characteristics of the proposed filter shows that an increase in the suppression of the out-of-band signal by 20 dB or more is obtained.

Information sources

1. G. Hanzel Handbook for the calculation of filters. Translation from English by V. A. Starostin, edited by E. A. Znamensky, Moscow, Sovetskoe Radio, 1974.

2. V.N. Bankov, L.G. Barulin, M.I. Zhodzishsky, etc. Radio receivers. Moscow, Radio and Communications 1984.

3. I.N. Dutyshev. Design and calculation of filters on quarter-wave short-circuited hairpin resonators. Electronic Engineering, Series 1, Microwave Engineering, Issue 5 (493), 2007.

Claims (1)

A microstrip microwave bandpass filter containing a dielectric substrate, on one side of which a grounded metallized base is applied, and on the other side are microstrip conductors in the form of hairpin resonators arranged in series and interconnected, one end of the resonator is short-circuited and the other open. the resonator is connected to the input, and the last to the output of the filter, characterized in that two microstrip conductors are additionally made, with one end of the first it is single with the middle of the first resonator, one end of the second conductor is connected to the middle of the last resonator, the other ends of the conductors are free.