A kind of side's ring defect ground structure microwave bimodule band-pass filter
Technical field
The present invention relates to a kind of side's ring defect ground structure microwave bimodule band-pass filter, belong to microwave filtering device technical field.
Background technology
As the Primary Component of radio communication front end, the characteristic of microwave filter is very big to the whole communication system performance impact.Radio communication need adopt volume little, the microwave filter that performance is high.For the microwave filter of realizing that volume is little, can adopt dual mode filter, step electric impedance resonator (SIR) and slow wave structure filter etc., another effective method are the positions between arrangement rationally and distribution resonator, as adopting sandwich construction or making the embedded arrangement of resonator.Improve filter characteristic, method commonly used is the progression that increases filter.Though increase the sideband characteristic that filter order can be improved filter, make the stopband of filter become more precipitous.But when characteristic was improved, the volume of filter increased on the one hand, and the loss of filter also increases on the other hand.Do not increase the progression of filter when improving again, well select for one during dual mode filter for the characteristic that makes filter.By suitable perturbed structure, two merger patterns in the dual-mode resonator are separated, produce two transmission poles, thereby reduced the volume of filter.This method has improved the characteristic of filter under the prerequisite that does not increase filter order.
Summary of the invention
The objective of the invention is, in order to adopt a kind of comparatively simple method to realize high performance microwave filter, by introducing the DGS dual-mode resonator, and adopt new perturbation and I/O mode, stopband at filter produces a plurality of transmission zeros, reaches the purpose of the stopband characteristic that improves filter.
Technical scheme of the present invention is that microwave filter of the present invention is made of the microstrip type input/output structure that is positioned at top layer and square ring defect ground structure (DGS) dual-mode resonator that is positioned on the ground plane; The annular DGS resonator in side adopts the perturbation and the nonopiate structure of horizontal symmetrical by novel perturbation method; Be used in combination horizontal symmetrical input and the excitation of output feeding classification, two degenerate modes of resonator are separated.
Signal is coupled to the square ring defect ground resonator that groove 1, groove 2, groove 3 and groove 4 be made of by microstrip line 5 by groove 2 by input port 7 inputs, and the back by groove 3, is coupled to microstrip line 6 by this resonator, passes through microstrip line 6 at last by port 8 outputs.Suitable control microstrip line 5,6 and the coupling between the groove can produce four transmission zeros in the passband edge of filter, have improved filter passband and stopband characteristic.Coupling between the DGS of ground plane dual-mode resonator two-mode can be by changing resonator the width of perturbation groove 1 control, thereby the bandwidth of control filters.The energisation mode of the annular DGS resonator bimodulus in side is that the width of top is 50%~80% o'clock of the width on its excess-three limit, can be in two transmission zeros of stopband generation of filter.The width of the overlapping area of microstrip line 5,6 and square groove 2,3 and microstrip line 5,6, the position of two other transmission zero of controllable filter makes them in passband edge.Adjust the external sort factor that tap position 7 and 8 can change input and output, make it to reach designing requirement.The filter of this novel perturbation DGS bimodulus structure is compared with passing filter, and the volume that can reduce filter reaches more than 1/2; By the coupling between input and output microstrip line and the Q-RING, produce two extra transmission zeros in passband edge, its attenuation outside a channel can reach-below the 15dB.
The method that described DGS bimodulus characteristic is separated by the width that reduces the resonator top obtains.The position on two limits of I/O coupled microstrip line and DGS dual-mode resonator can be overlapping, and the coupled outside excursion is big.With orthogonal arrangement was different in the past, the I/O coupled microstrip line adopts horizontal symmetrical to arrange.
The present invention's beneficial effect compared with the prior art is, the present invention is by adopting the DGS dual-mode resonator that loads novel perturbation, and input and output coupling microstrip and resonator have overlappingly, and the volume of filter can reduce 1/2; Simultaneously, get suitable input and output coupling microstrip 5 and the overlapping area between the square groove 2 and little, can produce four transmission zeros, the passband of filter and stopband characteristic are improved in the passband edge of filter with 5 width.
The present invention is applicable to frequency microwave communication.
Description of drawings
Fig. 1 is the structure chart that is positioned at the annular DGS dual-mode resonator in side of ground plane;
Fig. 2 is the structure chart of top layer input and output;
Among the figure: 1, four limits of 2,3 and 4 side's of being ring defect ground structure resonators, 5 and 6 is respectively the width of input and output coupled microstrip line, 7 and 8 is respectively that characteristic impedance is 50 ohm input port and an output port.
Embodiment
The specific embodiment of the invention as depicted in figs. 1 and 2, Fig. 1 is an annular DGS dual-mode resonator in side that is positioned at the novel perturbation of loading of ground plane, Fig. 2 is top layer input and output coupled structure, they are made on dielectric-slab.
The microwave band-pass filter of present embodiment, signal is coupled to the square ring defect ground resonator that groove 1, groove 2, groove 3 and groove 4 be made of by microstrip line 5 by groove 2 by input port 7 inputs, and groove 3 is passed through by this resonator in the back, be coupled to microstrip line 6, export by port 8 by microstrip line 6 at last.Suitable control microstrip line 5,6 and the coupling between the groove can produce four transmission zeros in the passband edge of filter, have improved filter passband and stopband characteristic.Coupling between the DGS of ground plane dual-mode resonator two-mode can be by changing resonator the width of perturbation groove 1 control, thereby the bandwidth of control filters.When being slightly less than the width on other three limits, its width can produce two transmission zeros at the stopband of filter.Groove 1 is wide to be 0.6mm, and other three grooves comprise that groove 2 and groove 3 are wide and are 1mm.I/O microstrip line 7,8 is wide to be 1.5mm.5,6 beelines of microstrip line are 12mm.The width of the overlapping area of microstrip line 5,6 and square groove 2,3 and microstrip line 5,6, the position of two other transmission zero of controllable filter makes them in passband edge.Adjust the external sort factor that tap position 7 and 8 can change input and output, make it to reach designing requirement.The filter of this novel perturbation DGS bimodulus structure is compared with passing filter, and the volume that can reduce filter reaches more than 1/2; By the coupling between input and output microstrip line and the Q-RING, produce two extra transmission zeros in passband edge, its attenuation outside a channel can reach-below the 15dB.I/O coupling line and resonator are on the Different Plane, are convenient to realize needed close coupling; Simultaneously, input and output are in the horizontal symmetrical position, are convenient to and other microwave circuit interconnection.The filter fundamental frequency of design is at the 5.2GHz place, produces four transmission zeros because band is outer, and the passband both sides surpass-and the resistance band of 15dB is 4GHz-7.2GHz.