SU1688309A1 - Band-pass filter - Google Patents

Abstract

This invention relates to frequency separation devices. The aim of the invention is to increase the selectivity and bandwidth. The band-pass filter contains a dielectric substrate 1, on the bottom surface of which a metal base (MO) is made, and on the top - a strip conductor 3, to which a quarter-wave strip cable (FSS) 4, short-closed at the end, is connected in parallel. A semiconductor gap (PS) is made in the MO, crossing with cr with strip conductor 3, one of which is located under MSP 4 symmetrically with respect to its edges, and the other end of its end is connected to a high-resistance reactive load. The high frequency signal propagates through a transmission line formed by the strip conductor 3 and MO. At frequency f0, the input resistance of the PNSP 4 is theoretically equal to infinity and the signal propagates along the transmission line without reflections, i.e. Attenuation zero takes place. Symmetrically with respect to this frequency, there are two additional frequencies with zero attenuation and the bandwidth increases, which is achieved by the interaction of the waves reflected from the reactivities created by MSP 4 and PS. 2 Il. &

Description

The invention relates to the field of radio engineering, in particular, to devices for frequency separation of signals.

The aim of the invention is to increase the selectivity and bandwidth.

FIG. 1 shows the proposed filter, top view; in fig. 2 - the same, bottom view.

The band-pass filter contains a dielectric substrate 1, on the bottom surface of which a metal base 2 is made, and on the top - a strip conductor 3, to which a quarter-wave strip cable 4 is connected, which is short-circuited at the end. Half-wave is made in the metal base 2

a slit intersecting with the strip conductor 3, one end of which is located under the quarter-wave strip loop 4 symmetrically with respect to its edges, and its other end connected to a high impedance reactive load 6.

Band-pass filter works as follows. The high-frequency signal propagates along the transmission line formed by the strip conductor 3 and the metal base 2. At the frequency fo, the input resistance of the quarter-wave stripline 4 is theoretically equal to infinity, and the signal propagates along the transmission line without reflections, i.e. there is a damping zero. Symmetrically with respect to this frequency, there are two dopols (X 00 00

with

o you

light frequency with zero attenuation. This is achieved by the interaction of the waves reflected from the reactivities created by the quarter-wave strip cable 4 and the half-wave gap 5. To provide three decay zeros, the following relations must be fulfilled

v, n 2Y4i + 1

tg Ch

2Usch2- where Yn, Usch1, Usch2 - conductivity of a quarter-wave strip cable 4, the gap under the cable 4 and outside it, respectively;

fo. fc is the bandwidth frequency;

f3 is the frequency of the attenuation band.

The connection of the half-wave gap 5 to the high-resistance reactive load 6 provides at this end its idle mode. Thus, the introduction of the half-wave band 5 provides three attenuation zeros and a damping pole, which leads to an increase in selectivity and bandwidth.

Claims (1)

The invention The band-pass filter containing a dielectric substrate on the bottom the surface of which is made of a metal base, and on the top is a strip conductor, to which a quarter-wave cable is connected in parallel, short-circuited at the end, differing by the fact that, in order to increase the selectivity and bandwidth, a half-wave gap is made in the metal base, crossing with a strip conductor, one end of which is located under the quarter-wave paddle loop is symmetrical about its edges, and its other end is connected to a high-resistance reactive load.  1 Figg