Art of Comparing Rfid Reader Power Outputs Isotropic Circular Polarized Antenna | Radio Technology | Antenna (Radio)

Please download to get full document.

View again

of 5
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Information Report



Views: 8 | Pages: 5

Extension: DOCX | Download: 0

Related documents
rfid power isotropico
  Art of comparing RFID reader power outputs 19 September 2011 Mirva SaarijärviA white paper describing how to compare RFID reader power otpts!I have recent # tmb ed into $ew RF%&s and RF'&s where RFID readers radiating power $igres are as(ed! And at the same time in some cstomer discssions it became obvios that it is not a wa#s c ear how to compare $igres o$ di$$erent $ormats! )e co ected this  paper together with one o$ *ordic ID&s RF grs +Mr! ,oni -eijari! .r goa is to e/p ain inan eas# wa# what the di$$erent RFID power $igres mean and how the# can be sed!RFID radiating power is an essentia $igre describing the per$ormance a thogh it mst benoted that it is not the on # one! ,o pt it simp # + more power ot $rom antenna mean that tags $rther awa# hear the reader + it is a good thing i$ ong reading distance is the goa ! t power otpt does not describe a aspects o$ the reader per$ormance! It does not describe receiver sensitivit# + $rom how $ar can a reader hear the tag it does not describe readers speed or abi it# to read tags withot orientation sensitivit# etc!,here are two common wa#s to show radiating power mi iwatt 3m)4 and some $orm o$ decibe s 3d4! 5omp e/it# arises when di$$erent t#pes o$ decibe $igres are compared + $ine i$ it is done correct # bt mista(es are easi # done! An e/amp e .ther things e6a + which reader has onger reading distance a reader with 70dm 31!0)4 8R' or a reader with 72dm 31!)4 8IR': )e wi give the answer ater in this artic e!Decibe s 3d4 describe re ations o$ two $igres in ogarithmic sca e!0d /;1<#7d /;2<#d /;=<#10d /;10<#20d /;100<#and+7d /;#>2+10d /;#>10)hen RFID readers power is discssed d is not jst a p ain d bt dm di etc! the part a$ter d describes into which the $igre is compared to! For e/amp e an antenna with gain 7di emits to the main direction 2 times the power o$ an isotropic re$erence antenna! ,he ?i? in di stands $or the isotropic re$erence antenna!RFID readers power otpt depends on 2 components! 'ower otpt going into the antennaand antenna gain! 'ower going into the antenna 3RF power4 is sa # given as mi iwatt  3m)4 or in dm! In this case dm describes the power compared to 1m)! In tab e one  be ow the dm to m) re ation is described!.ther component + antenna gain + is given as compared to some re$erence antenna!di describes gain compared to isotropic re$erence antennadd describes gain compared to re$erence dipo e antennadic describes gain compared to re$erence isotropic circ ar po ari@ed antenna)e have seen a so di being sed it re$ers to re$erence inear po ari@ed antenna bt the re ation to di is not c ear<4 and we don&t recommend se o$ di!,here is a c ear re ation between the estab ished re$erence antennas+ dipo e antenna radiates more to directions in 90 degree ang e to the antenna dipo e than idea isotropic antenna 0dd ; 2!1= di  3sorce www!ti!com4+ Isotropic circ ar po ari@ed antenna ? ooses? some o$ the radiation power in the circ ating po ari@ation de to po ari@ation mismatch when tag antenna is inear! As a res t0dic ; +7 di'ictre I stration o$ inear and circ ar po ari@ation! 3www!ti!com4In 8ropean egis ation radiating power imits are described in re ation to dipo e antenna and 8R' 38$$icient Radiating 'ower4 is sed as a measre! An e/amp e RF power is 2Bdm 3C00m)4 and antenna has gain o$ Cdi! 8R' ; 2Bdm  Cdi +2!1C ; ca! 70dm 31!0)4In ES egis ation 8IR' 386iva ent Isotropica Radiated 'ower4 is sed! 'ower is comparedto isotropic re$erence antenna! )ith same reader and antenna as above 3RF power is 2Bdm3C00m)4 and antenna has gain o$ Cdi4 8IR' ; 2Bdm  Cdi ; 72 dm 31!)4Answer to the 6estion posted above reader with radiating power o$ 1) 8R' same as reader with radiating power o$ 1!) 8IR'!Form as8R' in dm ; 3RF power in dm4  3antenna gain in di4 +2!1Cd this can be converted to m) sing tab e above8IR' in dm ; 3RF power in dm4  3antenna gain in di4 this can be converted to m) sing tab e abovedi ; dic + 7d 3in RFID se4di ; dd 2!1CdMore e/amp esreader with C00m) RF power antenna with dic gain+ C00m) ; 2Bdm+ 8R' ;2B dm  3dic +7d4 +2!1Cd ; ca! 2dm 370m)4+ 8IR' ;2B dm  3dic+7d4 ; 70 dm 31)4  reader with =00m) RF power antenna with C di gain+ =00m) ; ca 2dm+ 8R' ; 2 dm  =di +2!1Cd ; ca! 2 dm 370m)4+ 8IR' ; 2dm  =di ;70 dm 31)4Athors ,eem Ainasoja and ,oni -eijariFor more in$ormation p ease contact spportGnordicid!com<4 http>>www!nitehaw(!com>rasmit>ve7ont!htm ! In the re$erence ca c ation o$ di is done b# sbstracting 7d $rom dic which in $act means that di wo d be same as di! From antenna per$ormance point o$ view inear antenna is sa # a dipo e antenna!,his entr# was written b# Mirva Saarijärvi posted on 19 September 2011 oo(mar( the  perma in( ! Ho can  post a comment! 11 3 comments  on “Art of comparing RFID reader power outputs” 1!)od@imier@ 'aJ'osted 20 September 2011 at 1=0CB' se send me white paper abot crrent in antenna2!Steve )right'osted 21 September 2011 at 0CB70,his artic e is a bit mis eading as the power measrements described are on # app icab e in the $ar $ie d 3where the antenna beam has $ormed4! In the near $ie d 3where a ot o$ RFID ta(es p ace4 It is not certain the the power $ / densit# 3power on m) or Dbm4 is an accrate represenation o$ acta power eve ! ,he correct wa#to measre in the 8 and - $ie ds and ca c ate the power! I earned this when measring RF power eve s at aviation navigation aids $rom F 3100 K-@ *D4 to S band 37 L-@ A,5 Radar4 7!,eem Ainasoja'osted 22 September 2011 at 111C70
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks