Parallel One-sided Elliptic Function Transmission Line Filter

Abstract

The present invention proposes a parallel single-sided elliptic function filter composed of transmission line elements. The input signal is fed into the first parallel cross joint (2) from the input transmission line (1) and is divided into two transmission paths, which are respectively transmitted through the cascaded transmission line section ( 3) and the parallel transmission line section (4) are transmitted to the second parallel cross connector (7), and the two channels are synthesized and then output from the output transmission line (8). The two open-circuit transmission line stubs are respectively connected to two parallel cross connectors to adjust the reflected signal amplitude. For a given cutoff frequency f c , by selecting the parameters of each transmission line element, more than two frequencies are lower or higher than f c The non-zero finite frequency of refreflects the zero and forms a passband in the frequency band around it; at the same time, more than two frequencies are higher or lower than f c The non-zero finite frequency transmission zero point of , and forms a stop band in the frequency band around it, so that f c Nearby one-sided elliptic function filtering characteristics. The invention is suitable for the medium and lower bandwidth, low loss and high selectivity filter of microwave and millimeter wave frequency bands.

Description

technical field [0001] The invention relates to a system widely used in microwave and millimeter wave frequency band communication, radar and measuring instruments, etc., to control the frequency response of signals, block the transmission of frequency components of useless signals, and make the frequency components of useful signals pass through almost without attenuation filter. Background technique [0002] Filters are passive circuits widely used in microwave circuits and systems. They are used to achieve specific frequency selection characteristics. Filters can be divided into high-pass, low-pass, band-pass and band-rejection types according to transmission characteristics. The passband of the filter Properties such as insertion loss and stop band rejection have a great influence on the performance index of the circuit. With the increasingly tight frequency resources and the increasingly crowded spectrum, the radio system puts forward higher requirements for the freque...

AI Technical Summary

Problems solved by technology

However, the circuit implementation is complicated, and it is usually implemented by introducing cross-coupling between non-adjacent resonant cavities.

Although the synthesis and design of this filter with cross-coupling have been widely studied, its processing and debugging are difficult, which limits its engineering application.

[0004] In order to achieve good frequency selection characteristics near the working frequency band, band-pass filters and band-stop filters are mainly used at present. However, band-pass filters with steep transition band attenuation characteristics generally require multi-stage filters. Multi-stage filters are composed of a Composed of a series of mutually coupled resonators, the insertion loss is large, the in-band group delay and its fluctuation increase, and the volume is large

Multi-stage band-stop filters have the same disadvantages

A filter with a single high-Q resonant tank can achieve lower insertion loss, but this single-loop filter has a narrow bandwidth, which is difficult to meet the requirements of practical applications

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