CN206806478U - It is a kind of to load T-shaped minor matters in parallel and the Microstrip Low-Pass of defect ground structure - Google Patents

Abstract

The utility model discloses a kind of low pass filter for loading T-shaped minor matters in parallel and defect ground structure.It is in basic Microstrip Low-Pass, by loading T-shaped minor matters in parallel in the less series connection microstrip transmission line side of width, loads dumb-bell shape defect ground structure unit at the open stub back side of parallel connection, designs the Microstrip Low-Pass of Wide stop bands.The utility model method is simple, and cost is low, is easily integrated, and stopband is wider can to reach in general application requirement, and 2 to 3 frequency multiplication parasitic passbands can be suppressed, it is most important that can reduce the size of wave filter, reach the requirement of miniaturization.

Description

It is a kind of to load T-shaped minor matters in parallel and the Microstrip Low-Pass of defect ground structure

Technical field

It the utility model is related to filter field, it is more particularly to a kind of to load the small of T-shaped minor matters in parallel and defect ground structure Type Wide stop bands low pass filter

Background technology

Traditional high low-impedance filter and parallel branch line filter use the high low-impedance lines of 1/4 λ, thus its size compared with Greatly and the characteristic impedance of adjacent coupled microstrip line section has obvious mutation, humorous more than secondary so as to cause to produce in filter stop bend Ripple parasitic passband is unsatisfactory for the needs of Modern Communication System development.Document [1], which changes resonant element and the structure of coupling unit, to be made The parasitic passband for obtaining wave filter further suppresses, but filter size is larger；Document [2-4] substitutes string using open circuit T-shape section Join transmission line, obtain obvious stopband inhibition, but complex designing, and when high impedance micro-strip line impedance is larger and electrical length When smaller, the difficulty of technique making can be also increased using the design of open circuit T-shape section replacement high impedance series transmission line.

T-shape minor matters structure in parallel is that minor matters in parallel are loaded on into high impedance series transmission line side, forms band resistance filter Ripple branch road, to suppress the parasitic harmonic wave component in stopband；Improve the end of wave filter by the quantity and structural parameters that adjust minor matters Mouthful matching performance, realize the global optimization of the miniaturization of wave filter, low-loss and Wide stop bands performance.Therefore in design, only The resonant frequency of T-shape minor matters in parallel is located at the spuious passband central frequency to be limited, can just suppress harmonic wave well. Pass band is generally wider and is possible to discrete on frequency domain, in order to preferably utilize the band of T-shape minor matters in parallel Characteristic is hindered, multiple T-shape minor matters in parallel can be loaded, but the loading of multiple T-shape minor matters in parallel causes the volume of wave filter It can increase.

Bibliography

A kind of novel miniaturization Wide stop bands low pass filter design [J] microwave journals of the such as [1] Yang Maohui, Xu Jun, Zhao Qing, 2010,26 (4)：61-64

[2] Zhu Yizhi, Zhang Xiaojuan, Fang Guang have miniaturization ultra-wide stop-band filter design [J] of based on open circuit T-shaped structure Electronics and information journal, 2010,32 (9)：2282-2286

[3] Ning Junsong, design [J] Journal of UEST of China of the just auspicious miniaturizations ultra-wide stop-band low-pass filter of sieve, 2010,39 (2)：223-226

Design [J] electronic letters, vols of the Wide stop bands plane low pass filters such as [4] Ning Junsong, Luo Zhengxiang, sheep happy, 2008, 36(2)： 342-345

Utility model content

To solve the technical problem that the miniaturization of above-mentioned low pass filter and Wide stop bands can not take into account, reality of the present utility model Apply mode to be improved based on height impedance microstrip low-pass filter structure, introduce T-shaped parallel connection minor matters, minor matters in parallel are added High impedance series transmission line side is loaded in, forms bandreject filtering branch road.And (see Fig. 2 on the basis of T-section low pass filter in parallel And Fig. 4), reload dumbbell DGS structure in the open stub back side (see Fig. 3).Defect ground structure (Defected Ground Structure, DGS) structure, it is in the metal ground plane of microstrip line, corrodes and different nonmetallic of line width Unit, so as to change the distributed inductance of microstrip line and electric capacity, to improve all kinds of transmission characteristics of wave filter.DGS units have good Good band gap properties and Slow-wave effect, have relatively good characteristic impedance, and the stopband characteristic that can substantially improve circuit (for example suppresses Harmonic wave, improve efficiency, put forward high q-factor etc.), and make transmission line structure compacter.

It is of the present utility model to be characterised by basic Microstrip Low-Pass, in the less series connection microstrip transmission line of width Side loading one or more T-shaped minor matters in parallel, realize bandstop filter and are embedded into inside low pass filter, while in parallel connection The open stub back side loading dumb-bell shape DGS units, T-shaped minor matters in parallel and DGS units are combined devise it is one small The Wide stop bands Microstrip Low-Pass of size.

The utility model method is simple, and cost is low, is easily integrated, and stopband is wider, can reach in general application requirement.

Brief description of the drawings

Fig. 1 is basic model Microstrip Low-Pass structure,

Fig. 2 is the utility model Microstrip Low-Pass structure chart, adds two T shapes sections in parallel as seen from the figure, Reverse side adds a defect ground structure,

Fig. 3 is the utility model parallel connection T-section schematic diagram

Fig. 4 is the utility model defect ground structure schematic diagram

Fig. 5 is the utility model embodiment low pass filter schematic diagram

Fig. 6 is the utility model embodiment low pass filter simulation result figure.

Embodiment

With reference to embodiment and accompanying drawing, the utility model is described in further detail.

Fig. 2 is the utility model Microstrip Low-Pass structure chart.Its dielectric thickness is H=0.8mm, relative Jie of medium Electric constant is ε_r=2.2.Specifically the parameter of wave filter is：Cut-off frequency f₀=4GHz, in-band insertion loss is less than 0.5dB, defeated It is 50 Ω to enter output impedance.

Fig. 3 is ground structure figure the defects of being carried in reverse side.In dumbbell shape DGS, a length of 4mm of specific rectangle, a width of 2mm, Slit a length of 2.5mm, a width of 0.2mm.

Fig. 4 is loading T-shaped minor matters schematic diagram in parallel.The present embodiment L5 is 5.6mm, and L 2.75mm, wide w are 1mm.

Fig. 5 is the present embodiment low pass filter dimensional drawing.In this instance, long L1 is 4.5mm, and wide w1 is 1.5mm, long L2 For 8.3mm, wide w2 is 2mm, and wide w3 is 1.6mm, and long L3 is 6.8mm；

Fig. 6 is the simulation result figure of the present embodiment low pass filter.Passband echo reflection is small, and Insertion Loss is also smaller, excessively With precipitous, stopband has reached 11GHz in -20dB or so, and the size close to the parasitic passband of 3 frequencys multiplication, and wave filter is 18.6mm × 8.3mm, compared with conventional microstrip low-pass filter structure, size is obviously reduced, and meets the requirement of miniaturization.

Claims (1)

1. a kind of load T-shaped minor matters in parallel and the Microstrip Low-Pass of defect ground structure, it is characterised in that low in basic micro-strip On bandpass filter, in the less one or more T-shaped minor matters in parallel of series transmission lines side loading of width, meanwhile, in parallel connection The open stub back side loads dumb-bell shape defect ground structure unit, forms the Microstrip Low-Pass of Wide stop bands and miniaturization.