The Study Of UWB Filter Using Suspended Stripline

The Ultra-wideband（UWB）technology has some of the advantages, which othertechnologies don’t have, such as low power consumption, good for hiding, high datatransfer rate, low transmit power, system capacity, anti-interference ability, high safetyperformance. Therefore, UWB technology has become a hot research in the field ofwireless communication, ushered in a period of rapid development. The study of UWBsystem and its devices is beneficial to promoting the civilian use of ultra-widebandtechnology. As an important device in receiver front-end of microwave RF circuit, thestudy of high-performance, low-cost and miniaturization filter has very importantsignificance.This paper studies the UWB filters of suspended stripline, which is based onconventional filter design. Departure from the idea of stepped impedance resonator andlumped element, use suspended stripline to design miniaturization, low-loss,high-performance ultra-wideband filter. The main contents in this paper are as follows:1. Studied suspended stripline characteristics, its advantages and disadvantages,and gives the equivalent dielectric constant and characteristic impedance. On this basis,were given suspended stripline series and parallel inductance, capacitance of thephysical structure and the formula of calculating the component values.2. The basic characteristics of the half-wavelength stepped impedance resonatorare analyzed, and give the equivalent circuit diagram of the stepped impedanceresonator. Suspended stripline linear type stepped impedance resonator as a filterresonant unit. Use suspension stripline upper and lower coupling to achieve a largerseries capacitor as the inter-stage coupling structure between resonance units, and givesthe formula to extract the coupling coefficient between resonance units. Finally, a lowloss ultra-wideband filter is designed.3. Suspended stripline hairpin type stepped impedance resonator replace linear typestepped resonator as a filter resonance unit. The design method is same as the linearfilter. Low loss, small size and ultra-wideband filter is designed, which greatly reducesthe size of the filter in the longitudinal direction. 4. Based on suspended strip-line transmission line equivalent to lumped elements,use lumped element circuits to achieve ultra-wideband filter. Then with suspensionstrip-line structure to replace inductors and capacitors to achieve the ultra-widebandfilter. The design process is simple, easy to operate. The final design of the filterpass-band range3-13GHz, with4.3octave bands. The band rejection at1.8GHz and14.2GHz is more than40dB, and the length width height of the entire filter is30mm18mm12mm. The advantages of this filter are high octave bands, high-bandrejection, small size and low loss.