SU1730690A1 - Band-pass filter - Google Patents

Abstract

Use - in microwave frequency selective stripline devices. The purpose of the invention is to eliminate spurious bandwidths. The band-pass filter contains a dielectric substrate 1 on which a conductor 2 is placed, to which, at equal distances, short-circuited 3 and disconnected 4 loops are connected to one another from one another. Short-circuited 3 and open 4 loops are made irregular with a given law of wave impedance variation along the length, providing displacement of one pole of the impedance of short-circuited loops 3 by half the frequency range between the poles in the direction of increasing frequency, and for open loops 4 - by the same value in the direction decreasing the frequency, thereby achieving one bandwidth and eliminating spurious bandwidths. 2 silt, (L S

Description

The invention relates to a microwave technique and can be used in strip-frequency-selective devices.

The aim of the invention is to eliminate spurious bandwidths.

FIG. 1 shows a band-pass filter design; in fig. 2 - offset of zeros of input resistance of irregular short-circuited loops and poles of input conductivity of the open loops,

The band-pass filter contains a dielectric substrate 1, on one side of which there is a grounding base (not shown), and on the other side - a strip conductor 2, to which at short distance from one another are connected short pairs of loops 3 and open circuit loops 4. Each loop 3 and 4 is made with a characteristic impedance varying in the direction from the point of its connection to the conductor

Wi (g) Wi x

. “| / Yn tg yn r tg a r + 1, 2 x yn /“ | tg yn r tg a t + 1

where 1,2,30

Wi (d) Wk3 (r): Wi Wks; “1 O, W2 (r) Wxx (r); W2 - W ;; x; "2 0n.

35

Wk3 is the wave impedance of the short-circuited stub in the initial section;

Wxx is the wave impedance of the open loop in the initial section;

On 3 PP; “N 2; up 2.5 sh0,

 - average circular frequency bandwidth,

tЈ (0 - gz); tz - delay time on the length of the loop.

Band-pass filter works as follows.

The microwave signal entering the strip conductor 2 passes through it in the passband, when the input resistances of the loops 3 and 4 are high, and is reflected in the stopband.

The combination of short-circuited and

twisted loops 3 and 4 allows you to eliminate

0

50

five

0

five

0

five

five

all of the parasitic bandwidth due to the compensation of the input impedance poles of some loops by 3 input resistors of the other loops 4. To provide the passband, one of the poles of short-circuited loops 3 is shifted towards higher frequencies by half the frequency range between the poles, and one of the poles of open loops 4 is shifted by the same amount towards the lower frequencies, as shown in FIG. 2. For this purpose, the short-circuited loops 3 and the open loops 4 are made with characteristic impedances varying according to the above ratio.

Claims (1)

Claims of the invention A band-pass filter containing a dielectric substrate, on one side of which a grounding base is placed, and on the other side a strip conductor, to which pairs of loops are connected at the same distance from one another, characterized in that, in order to eliminate spurious bands the transmissions, some pairs of loops are made short-circuited, and the others are open-circuited, and each loop is made with a characteristic impedance varying from the point of its connection to the conductor Wi (t) W, x hg h.1 Cs g tg gl t + 1 2 K / «i tg ugg r tg« i r + 1 where 1,2; Wi (t) Wk3 (t): Wi Wk3; “1 - Q,; W2 (t) Wxx (r); W2 Wxx; "2 (On Wk3 is the wave impedance of the short-circuited stub in the initial section; Wxx is the wave impedance of the open loop in the initial section; Qi 3 Ш0; Wn 2 Sho; yn 2.5 a) 0; co0 average circular frequency bandwidth; Tt (0 - ts); t3 - delay time on the length of the loop.