DESARROLLO DE ANTENAS PARA LA TECNOLOGÍA DE RFID PASIVA EN LA BANDA DE UHF (902A928MHZ)

Abstract

The' technology' of' RFID' systems' are' frequently' used' in' the' objects' identification,' control' and' tracking.' These' systems' are' formed' by' a' reader,' the' propagation' media' (the' free' space)' and' a' tag' that' is' fixed' on' the' object' to' be' identified.' The' tags' for' RFID' systems' are' formed' by' an' antenna' and' an' integrated' circuit,'that'contains'the'information'of'the'object'to'identify.'Some'RFID'systems'use' electromagnetic' neardfield' inductive' coupling' and' operating' at' the' high' frequency' band' (HF)' and' very' high' frequency' band' (VHF).' The' RFID' technology' for' far' field' applications'operates' at' the'ultra'high' frequency' (UHF)'band'and'microwaves.'Both' technologies'use'RFID'active'and'passive'tags,'the'first'requires'a'battery'to'operate' and'transmit'electromagnetic'energy'continuously'to'the'media'to'be'recognized'by'a' reader,' that' area' is' bigger' than' 50' m.' However,' the' passive' tag' only' works' when' electromagnetic' energy' bearing,' that' is' fed' with' the' signal' frequency' (RF).' Its' coverage'is'less'than'20'm.' One'of'the'main'challenges'of'RFID'technology'with'passive'tags'is'to'achieve' greater'operating'range,'which'depends'on'the'gain'of'the'antenna,'coupling'between' the'integrated'circuit'and'antenna,'and'the'sensitivity'of'the'integrated'circuit.' ' ' Instituto'Politécnico'Nacional.' ' iii' This'thesis'describes'the'design,'optimization'and'construction'of'passive'tags' for' the'RFID' systems,' so' it' is' first' presented' a' summary' of'RFID' systems' to' give' a' general'framework'of'the'importance'of'the'work'of'research'related'with'this'thesis.' Secondly,'we'present' the'analysis'of'passive'RFID' tags,'with'emphasis'based'on' the' impedance' characteristic' of' the' integrated' circuit'and' design'antennas' to'match' the' integrated' circuit.'This' process' is' carried'out' looking' to' not'degrade' the' gain' of' the' antenna.'Finally,' a'process' is' described' of' the'optimization'of' the'parameters'of' the' antenna'for'the'best'performance.' To' corroborate' the' theoretical' analysis,' four' antennas' are'designed' based' on' the'technique'of'meandering'each'antenna'with'an'approximate'gain'of'1'dB,'which' looks'for'an'optimization'of'its'coupling'with'the'integrated'circuit,'through'a'program' based' on' genetic' algorithms' made' in' Matlab,' that' communicates' with' an' electromagnetic'simulator'to'obtain'the'parameters'of'each'antenna.'Once'the'design' process'is'concluded,'the'results'are'verified'through'the'characterization'process,'so' that'the'outcomes'are'compared'to'those'in'computer'simulation.'