STRIP NON-REFLECTING BAND-PASS TUNABLE FILTER Russian patent published in 2024 - IPC H01P1/203 

FIELD: radio engineering.

SUBSTANCE: invention relates to microwave radio engineering, specifically to non-reflecting band-pass tunable microwave filters. Essence: the filter contains the first and the second connected strip lines, two switches, frequency-selective circuits. Input of the second strip line is connected to the input of the first switch. First and second outputs of the first switch are connected to inputs of the first and second frequency-selective circuits, respectively. Outputs of frequency-selective circuits are connected to common conductor. First frequency-selective circuit is made in the form of series-connected first inductance and first capacitance, forming a series oscillatory circuit with resonance frequency ƒ₁, to which a resistor with resistance equal to input resistance on the side of input of the second strip line is connected in parallel. Second frequency-selective circuit is made in form of series-connected second inductance and second capacitance, forming series oscillating circuit with resonance frequency ƒ₂, to which a resistor with resistance equal to input resistance on the side of input of the second strip line is connected in parallel. Input of the second switch is connected to the output of the first strip line. Outputs of the second switch are connected to inputs of the third and fourth frequency-selective circuits. Values of inductances and capacitances of the third frequency-selective circuit are equal to the first inductance and the first capacitance of the first frequency-selective circuit and form the third serial oscillatory circuit with frequency ƒ₁, to which a resistor with resistance equal to the input resistance on the side of the output of the first strip line is connected in parallel. Values of inductances and capacitances of the fourth frequency-selective circuit are equal to the second inductance and the second capacitance of the second frequency-selective circuit and form the fourth serial oscillatory circuit with frequency ƒ₂, to which a resistor with resistance equal to the input resistance on the side of the output of the first strip line is connected in parallel. Connection of first and third frequency-selective circuits to first outputs of first and second switches is performed synchronously, as a result of which the filter is tuned to frequency ƒ₁. Connection of the second and fourth frequency-selective circuits to the second outputs of the first and second switches is performed synchronously, as a result, the filter is tuned to frequency ƒ₂.

EFFECT: elimination of periodicity of pass bands, provision of middle frequency tuning of pass band, reduced reflection from the input and output of the filter at out-of-band frequencies while maintaining the frequency selection function when tuning the transmission frequency, reduced dimensions.

1 cl, 10 dwg