The Preparation Of Carbonyl Iron Based Microwave Absorber For Isolator Load

This resear ch ai med at solving the mainly present pr oblem ofmi crowave absorbing materials with poor integrated performance of theabsorption loss and power-handling, which is not satisfied with theneed of development on future mi crowave system, and the vi ew ofabsorbing material’s desi gn for load was put forward. Under the view,mi crowave absorbing composites were prepared by hot-pressing withepoxy resins as matrix, and carbonyl iron powder, W-type Bariumferri tes, BaTi O3as absorber. The voltage breakdown strength,absorption loss, mi crostructure and electromagnetic parameters of theabsorbing materials was mea sur ed, and the characteristics of isolatorusing the pr epared absorber were tested. The test results are as follows:（1） The composites with high content and well dispersed absorbercan be prepared by hot-pressing.The absorption loss of absorbingmateri al s was gr eat large, which were prepared under9MPa of for mingpressure, but the breakdown strength decreased with the content of ironpowders increasing.（2） For the flake-shaped carbonyl iron/epoxy resins composites,the sa mple has higher absorption loss of7.5dB·mm-1at8GHz, but thebreakdown voltage was so low that it can’t meet the application need.The flake-shaped carbonyl iron particles were coated a layer of SiO₂b ySt ber method. The breakdown strength of epoxy resins compositeswith SiO₂coated carbonyl iron i mproved with concentration of TEOS.When flake-shaped carbonyl iron particles were coated wi th the TEOSconcentration of1.2%, the absorption loss of composites was5.1⁷.3dB·mm-1from8GHz to12GHz, and the br eakdown voltage can reach upto930V· mm-1.（3） BaZn0.6Co1.4Fe16O27and BaTi O3powder were blended wit hcarbonyl iron powder respectively, whic h were both prepared by sol-gel,and then filling the m into epoxy resin to for m composites. Theabsorption loss and breakdown voltage of BaZn0.6Co1.4Fe16O27/carbonyliron powder comp osites reduced and increased respectively with content of ferrite， and both of the two prop er ti es di d not meet t heexpect ant target s. The two properties of BaTi O3/carbonyl iron powderco mposites were similar in change laws to BaZn0.6Co1.4Fe16O27/carbonyl iron powder composites, but when content of BaTi O3was40%,absorption loss of composite was5.3dB·mm-1at8GHz and breakdownvoltage was770V·mm-1, so both of which meet the expectedper for man ce.（4） We made the samples, whose properties reach to expectanttargets, into absorption load. And then the load was used in GDP9046type isolator of8¹2GHz, the index was followed: VSWR<1.4,insertion loss<0.4dB, isolation≥20dB on bandwidth of100%and≥30dBon bandwidth of30%. When the load was used GTP9086A type isolatorof6¹8GHz, the index of device was followed: VSWR<1.3, insertionloss≤1.2dB, isolation≥13dB on bandwidth of100%,≥15dB onbandwidth of50%and≥20dB on bandwidth of20%.