Stripline low-pass filter

Abstract

The invention discloses a stripline low-pass filter and aims to provide a low-pass filter with low passband attenuation, steep near-end stopband attenuation and high far-end stopband suppression. According to the technical scheme, the stripline low-pass filter is characterized in that a first-level five-order elliptic function filter unit is formed by trapezoid stripline branch nodes S1, S2 and S3which are distributed as a Y shape and two high-impedance U-shaped coupled series branch nodes W1 and W2 which are connected with the trapezoid stripline branch nodes S1, S2 and S3; a second-level five-order elliptic function filter unit is formed by trapezoid stripline branch nodes S4, S5 and S6 which are distributed as a Y shape and two high-impedance U-shaped coupled series branch nodes W3 andW4 which are connected with the trapezoid stripline branch nodes S4, S5 and S6; a ten-order Chebyshev filter unit is formed by stripline branch nodes L1, L2, L3, L4 and L5 on the same plane and T-shaped open-circuit branch nodes T1, T4 and T5 which are pairwise vertical to each other in a same direction; an input step impedance unit is formed by stripline step impedance P1; and an output steppedimpedance unit is formed by stripline step impedance P2.

Description

technical field [0001] The invention relates to the field of wireless communication, radio frequency measurement, and low-pass filter of mobile phone comprehensive testing instrument. More specifically it relates to stripline low pass filters. Background technique [0002] A low-pass filter is a common microwave passive device. It is widely used in microwave test system, communication system, radar system and other systems. As a frequency selection device, low-pass filter can be used to suppress interference signals and harmonic signals. Due to the parasitic effect of the transmission line at high frequencies, the theoretically calculated distribution parameter values ​​are quite different from the actual values, which makes the stripline low-pass filter using the traditional structure unable to meet the design requirements. [0003] In the classic low-pass filter design, it is mainly divided into three categories: elliptic function filter, Chebyshev filter and Butterwort...

AI Technical Summary

Problems solved by technology

In the design of high-frequency filters, since the series capacitance and inductance are difficult to realize, the stop-band attenuation of the low-pass filter designed with the traditional stripline structure is relatively smooth, and it is difficult to effectively suppress the stop-band at low frequencies.

However, the scheme of using traditional low-pass filter and band-pass filter to cooperate with segmentation can achieve better spurious suppression, but it increases the loss of the circuit, the complexity of the circuit and the size of the circuit.

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