Michael Elsdon Michael Elsdon 1 1 12/27/09 12/27/09Reduced Size Microstrip Patch Reduced Size Microstrip Patch Antenna DesignAntenna DesignPresented by: Presented by:Dr. MichaelElsdonDr. MichaelElsdon michael.elsdon@unn.ac.uk michael.elsdon@unn.ac.ukNorthumbria Communications Research Lab Northumbria Communications Research LabSchool of Computing, Engineering and Information Sciences, School of Computing, Engineering and Information Sciences,Northumbria Northumbria University University AN OVERVIEWAN OVERVIEW12/27/09 12/27/09 Michael Elsdon Michael Elsdon 2 2PresentationOverviewPresentationOverview BasicPatchAntennaOperation BasicPatchAntennaOperation Rationale/Background to Research Rationale/Background to Research Reduced Size Solutions Reduced Size Solutions Mathematical Analysis of Slot LoadedMathematical Analysis of Slot Loaded Structures Structures NewPatchDesignsNewPatchDesigns Summary Summary12/27/09 12/27/09 Michael Elsdon Michael Elsdon 3 3))))))E (if Vertically Polarised)Propagating WaveHAntenna Radiating:~ZoIIVG+-Antenna StructureRF Signal SourceTransmission LineZoDefinition of an AntennaA usually metallic device for radiating or receiving radio wavesA transitional structure between free space and a guiding device* Websters DictionaryGUIDING DEVICE FREE SPACE12/27/09 12/27/09 Michael Elsdon Michael Elsdon 4 4Antenna Receiving:((((((E (if Vertically Polarised)Propagating WaveHZoIIAntenna StructureRF ReceiverTransmission LineZoDefinition of an AntennaA usually metallic device for radiating or receiving radio wavesA transitional structure between free space and a guiding device*Websters DictionaryGUIDING DEVICE FREE SPACE12/27/09 12/27/09 Michael Elsdon Michael Elsdon 5 5Standard Patch AntennaStandard Patch AntennaLhG r o u n d P l a n er s u b s t r a t e xzTop ViewSide ViewFringing Electric Fields from the Two Edges of the Patch Add to Cause Radiation))))I~ /2EEConsists of a metallic strip placed above aConsists of a metallic strip placed above a ground plane ground plane12/27/09 12/27/09 Michael Elsdon Michael Elsdon 6 602468101210 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50Patch Length, mmResonant Frequency, GHzMost Important Design ConsiderationResonant Frequency ? Er fixed by substraterLcf 212/27/09 12/27/09 Michael Elsdon Michael Elsdon 7 7Examples of Patch Antenna StructuresExamples of Patch Antenna StructuresAdvantages Disadvantages Top View Edge ViewPrinted PatchSuspended PatchStacked Patches~/ 2~/ 2SubstratePatchGround PlanePrinted PatchGround PlaneSuspended Patch~/ 2SubstrateSuspended Patch~/ 2Ground PlaneSuspended PatchesPrinted Patch~/ 2SubstrateStacked Patches~/ 2 Very Low Profile Simplicity Good Production Repeatability Ultra Narrow Bandwidth~ 1% for VSWR = 1.2 : 1 Substrate Cost Limited Beamwidths Possible Low Profile Improved Bandwidth~ 10% - 15% for VSWR=1.2 :1 Excellent Production RepeatabilitySubstrate Cost Limited Beamwidths Possible Broadband: >15% Fairly Low Profile Substrate Cost Limited (Narrow) Beamwidths PossibleH-Plane PatternPerpendicular to PatchE-Plane PatternPerpendicular to Patch*Thanks to S. Foti *Thanks to S. Foti12/27/09 12/27/09 Michael Elsdon Michael Elsdon 8 8Microstrip Feed~/ 2~/ 2SubstratePatchGround PlanePrinted Patch Microstrip TrackMicrostrip TrackProbe FeedExamples of Patch Antenna ExcitationExamples of Patch Antenna ExcitationPros and Cons Pros and ConsPlanar PlanarEasy to fabricate andEasy to fabricate and match matchSimple to model Simple to modelSpurious feed radiation Spurious feed radiationCannot Optimise Feed andCannot Optimise Feed and Patch SubstratePatch Substrate requirements requirementsPros and Cons Pros and ConsEasy to fabricate Easy to fabricateEasy to impedanceEasy to impedance match matchNon-Planar Non-PlanarNarrow Bandwidth Narrow Bandwidth~/ 2~/ 2SubstratePatchGround PlanePrinted PatchFeed Point12/27/09 12/27/09 Michael Elsdon Michael Elsdon 9 9Slot-Coupled Microstrip FeedProximity Coupled~/ 2~/ 2SubstrateSuspended PatchGround PlaneSuspended Patch(s)Microstrip TrackMicrostrip TrackExamples of Patch Antenna ExcitationExamples of Patch Antenna ExcitationPros and Cons Pros and ConsAllows independentAllows independent optimisation of feedoptimisation of feed and patch substrate and patch substrateDifficult to fabricate Difficult to fabricateNon-planar Non-planarPros and Cons Pros and ConsIndependentIndependent optimisation of feed andoptimisation of feed and patch substrate patch substrateDifficult to fabricate Difficult to fabricateNon-planar Non-planar~/ 2SubstrateGround PlaneSuspended Patch~/ 2Microstrip Track SlotMicrostrip Track*Thanks to S. Foti for*Thanks to S. Foti for Diagrams Diagrams12/27/09 12/27/09 Michael Elsdon Michael Elsdon 10 10~/ 2~/ 2SubstratePatchGround PlanePrinted Patch Microstrip TrackMicrostrip TrackWhy ? Why ?Planar PlanarEasy to fabricate and match Easy to fabricate and matchSimple to model Simple to modelLow Profile Low ProfileGood production repeatability Good production repeatabilityChoice of Antenna StructureChoice of Antenna StructurePrinted Patch Antenna with Microstrip Feed12/27/09 12/27/09 Michael Elsdon Michael Elsdon 11 11Antenna Impedance Matching Network Input Typical Patch Antenna Performance87.96 1.7 330 50 3.17Efficiency(%)Gain(dB)FBW(%)AntennaInputImpedanceSourceImpedanceResonantFrequency(GHz)Typical Example 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 12 12Patch Antenna Summary Patch Antenna Summary AdvantagesLow Cost using PCBLightweight and thin profileEasy integration with MICDisadvantagesRestricted BandwidthSeveral losses may reduce efficiency Low Gain dictated by size / substrateFuture ChallengesFuture Challenges Bandwidth Extension Techniques Control of Radiation Patterns Reducing Losses / increasing efficiency Improving feed networks Size Reduction techniques12/27/09 12/27/09 Michael Elsdon Michael Elsdon 13 13Rationale for PhDRationale for PhDPatchAntennanowestablishedandusedinwiderangeofPatchAntennanowestablishedandusedinwiderangeof communication systems, e.g. radar, satellites, GPS.communication systems, e.g. radar, satellites, GPS. FuturerequirementforFuturerequirementfor SMALLERSMALLERCommunicationCommunication Systems SystemsCircuitryassociatedwithcomm.systemshasreducedCircuitryassociatedwithcomm.systemshasreduced considerably in sizeconsiderably in size This is NOT TRUE of AntennasThis is NOT TRUE of Antennas CostlargelybasedonSizeThusanysizereductionCostlargelybasedonSizeThusanysizereduction greatly welcome greatly welcome12/27/09 12/27/09 Michael Elsdon Michael Elsdon 14 141. 1. Investigate Present Techniques for Reducing PatchInvestigate Present Techniques for Reducing Patch Antenna Size and Identify most appropriate technique Antenna Size and Identify most appropriate technique2. 2. DevelopAnalyticalModeltodeterminethe DevelopAnalyticalModeltodeterminetheperformanceofthechosenpatchstructure performanceofthechosenpatchstructure3. 3. Analysetheeffectofdesignparametersonpatch Analysetheeffectofdesignparametersonpatchperformanceandidentifyassociatedtrade-offs performanceandidentifyassociatedtrade-offs4. 4. Proposenewdesigns for reducedsizepatch Proposenewdesigns for reducedsizepatchantennasthatovercomesomeofthetrade-offsassociated antennasthatovercomesomeofthetrade-offsassociatedwithpresentdesigns withpresentdesignsProject Aims12/27/09 12/27/09 Michael Elsdon Michael Elsdon 15 15xLWy0BACKGROUND: Voltage and Current Distribution BACKGROUND: Voltage and Current Distribution( )

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.| by nax mk y xn m n mcos cos ,, , Associated eigenfunctions are given by: Fields within patch are described by 2D wave equation02,2222 ++Z n mz zE kyExE0 xEZ0 yEZ0 yEZ0 xEZMagnetic Wall Boundary 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 16 16x 0zLhL/2 IVx 0zLhL/2 L/4 3L/4 I Vx 0zLhL/2 L/6 L/3 2L/3 5L/6 V ITM01 modeTM02 modeTM03 modeCurrent VoltageCurrentCurrent Maxima MaximaVoltageVoltage Minima MinimaBACKGROUND: Voltage and Current Distribution BACKGROUND: Voltage and Current Distribution12/27/09 12/27/09 Michael Elsdon Michael Elsdon 17 17x 0zLhL/2 IVx 0zLhL/2 L/4 3L/4 I Vx 0zLhL/2 L/6 L/3 2L/3 5L/6 V ITM01 modeTM02 modeTM03 modeCurrent VoltageCurrent Minima Current MinimaVoltageVoltage Maxima MaximaBACKGROUND: Voltage and Current Distribution BACKGROUND: Voltage and Current Distribution12/27/09 12/27/09 Michael Elsdon Michael Elsdon 18 18Methods of Reducing Patch Size1. 1. High Permittivity Substrate High Permittivity Substrate2. 2. Folded Patch Folded Patch3. 3. Shorting Pin Shorting Pin 4. 4. SlotLoaded Ground Plane SlotLoaded Ground Plane 5. 5. SlotLoaded Patch SlotLoaded Patch6. Miscellaneous Techniques12/27/09 12/27/09 Michael Elsdon Michael Elsdon 19 191. Use of High Permittivity SubstraterLcf2Resonant Frequency of Conventional Patch:Principle of OperationObvious way to reduce patch size is to increase rLhG r o u n d P l a n er s u b s t r a t e xzSide ViewTop View12/27/09 12/27/09 Michael Elsdon Michael Elsdon 20 20Problems Such substrates are often ceramic based and thus more expensive Q Factor increases with permittivity, thus reducing BW Higher permittivity often equivalent to high dielectric losses (1)051015202530354045501 2 3 4 5 6 7 8 9 1011121314 15161718 1920Substrate PermittivityPatch Length, mmfo = 3GHzLhG r o u n d P l a n er s u b s t r a t e xz12/27/09 12/27/09 Michael Elsdon Michael Elsdon 21 212. Folded PatchGr ound planeBentedge Air substr at ePatchPrinciple of Operation Method involves use of an inverted U-shape structure Excited current path of the TMmn mode is lengthened Reduced resonant frequency for a fixed projection area Allows incorporation of air substrate for increased bandwidth12/27/09 12/27/09 Michael Elsdon Michael Elsdon 22 222. Folded PatchGr ound planeBentedge Air substr at ePatchProblems Non Planar Structure Size Reduction at expense of increased volume Complex Manufacturing Process12/27/09 12/27/09 Michael Elsdon Michael Elsdon 23 233. Shorted Patch 3. Shorted Patch shorting wallground planeshorting plateground planeshorting pinground plane(a) (b) (c)Principle of Operation Use of an edge shorted patch (a) makes the patch operate as a /4 structure Antennas Physical length is reduced by for a fixed operating frequency Greater size reduction can be achieved using a partial shorting wall (b) or a single shorting pin (c)12/27/09 12/27/09 Michael Elsdon Michael Elsdon 24 24dSLshorting pinyxmicrostripfeedWPrinciple of Operation Null-voltage point for TM01 mode exists at centre of patch Size reduction achieved by shifting the null voltage point Shifting shorting pin towards radiating patch edge shifts null-voltage point, thus reducing resonant frequency Maximum size reduction achieved when shorting pin placed at centre of radiating patch edge x 0zLhL/2IVVoltageVoltage Distribution Distribution12/27/09 12/27/09 Michael Elsdon Michael Elsdon 25 2511.051.11.151.21.251.30.51.52.53.54.55.56.57.58.59.510.511.512.513.514.5Shor ting Pin Position dS, mmResonant Frequency, GHzdSLshorting pinyxmicrostripfeedW12/27/09 12/27/09 Michael Elsdon Michael Elsdon 26 26E-Pl a neRadi ation-80-70-60-50-40-30-20-100-90-80-70-60-50-40-30-20-100102030405060708090Theta,degree sMagnitude, dB co-polx-polH-Pl ane Radi ati on-80-70-60-50-40-30-20-100-90-80-70-60-50-40-30-20-100102030405060708090Theta,degreesMagnitude, dB x-polco-polProblems Strict manufacturing tolerances (feed must be close to shorting pin) May be difficult to excite using a planar feed Presence of shorting pin / plane produces a dip in the E-plane radiation Large levels of cross-polarisation in the H-plane12/27/09 12/27/09 Michael Elsdon Michael Elsdon 27 27via holefor feedradiating patchin frontradiating patchWLrxy4. Slot Loaded Ground Plane4. Slot Loaded Ground PlanePrinciple of Operation Insertion of slots in the ground plane meanders the current path of TM modes Results in reduced resonant frequency and hence size reduction Meandering effect of the ground plane effectively lowers the Q factor, thus suggesting increased BW 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 28 28Problems Significant back radiation Less power available to transmit-100-90-80-70-60-50-40-30-20-100-180-160-140-120-100-80-60-40-20 020406080100120140160180Theta, degreesMagnitude, dBx-polco-polE-Plane Pattern12/27/09 12/27/09 Michael Elsdon Michael Elsdon 29 295. Slot Loaded Patch 5. Slot Loaded Patch Principle of Operation Insertion of slots in patch lengthens current path Reduced Resonant frequency and size reduction With correct selection of slot dimension, can produce reduced size, dual frequency and wideband patch antennas Standard Patch AntennaSlot Loaded Patch Antenna12/27/09 12/27/09 Michael Elsdon Michael Elsdon 30 30Resonant Frequency v SlotSize1.92.12.32.52.72.93.10 2 4 6 8 10 12 14 16 18 20 22 24 26 28Ls = Ws, mmResonant Frequency, GHzL sLWsWFeedpointBasic Slot Loaded Patch Example12/27/09 12/27/09 Michael Elsdon Michael Elsdon 31 31Best Solution Slot Loaded Patch ?1. 1. High Permittivity Substrate: High Permittivity Substrate:reduced BW, increased dielectric losses, increased cost2. 2. Folded Patch: Folded Patch:increased volume, complex manufacturing process3. 3. Shorting Pin: Shorting Pin: problems with radiation pattern, feeding and manufacturing tolerances4. 4. SlotLoaded Ground Plane: SlotLoaded Ground Plane: problems with back radiation, less transmission power5. 5. SlotLoaded Patch: SlotLoaded Patch: can produce wide range of designs: Reduced Size Single Frequency, Dual Frequency, Wideband12/27/09 12/27/09 Michael Elsdon Michael Elsdon 32 32Still Problems with Slot Loaded Still Problems with Slot Loaded Patch Antennas !Patch Antennas ! Lack of theoretical investigation to Lack of theoretical investigation to supportdesign of reduced size slot supportdesign of reduced size slot loaded structuresloaded structures Lack of Research into the trade-offs from Lack of Research into the trade-offs from such designs such designs Little work exists on the use of planar fed Little work exists on the use of planar fed reduced size patch antennasreduced size patch antennas12/27/09 12/27/09 Michael Elsdon Michael Elsdon 33 33Mathematical Analysis of Slot Mathematical Analysis of Slot Loaded StructuresLoaded StructuresL LWLLsWsW s W sLsLsL1 L3 L2W2P1P1P1 Several possible modelling approaches for analysing patch performanceTransmission Line, Cavity, Co-planar multi-port network, full-wavemodelling Need to ascertain the most suitable approach for slot loaded structures 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 34 34Possible Possible ModellingModelling Approaches:Approaches: Full-wave Modelling:Involves the solution of Maxwells equations for the electric current distributions on thepatchRequires considerable computer resources and yields little physical insightTransmission Line Model: Based upon the assumption that the patch is a wide microstrip transmission linePresence of slot loading changes the structure of the patch suggesting this assumption isno longer validCavity Model:Treats patch as a thin cavity TMz mode cavity with magnetic wallsOnly applicable for geometries for which the wave equation can be solved by separationof variables (e.g. square, rectangular, circular)Coplanar Multiport Network Model with Segmentation:Generalisation of Cavity ModelSuitable for Irregular Geometries 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 35 35Example:Example:Segmentation Analysis of Slot Loaded PatchSegmentation Analysis of Slot Loaded PatchModelling Steps Modelling Steps1. Decompose patch into regular elemental segments2. Develop Multi-port Network Models of each segment3. Synthesise each segment to reconstruct original patch structure 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 36 36LWl1w1l2l2w2w2HolePatchFeedpointl2l2W Wsegmentsegment1 212segmentsegmentStep 1: Patch Decomposed into 4 Segments Step 1: Patch Decomposed into 4 Segments12/27/09 12/27/09 Michael Elsdon Michael Elsdon 37 37

c ports1segmentl2Wp portspport s1segmentl1w2cport s++==Step 2: Alpha and Beta Sections RecombinedStep 2: Alpha and Beta Sections Recombined to form gamma segmentto form gamma segment ]]]

]]]

01121 cp ccpc pp pZ ZZ Z Zl3 = L - l2l2w2segment1pportspportsp port]]]]]]]

pnpn pn p pn ppnp p p p ppnp p p p pppZ Z ZZ Z ZZ Z ZZ...... ... ... .........2 12 2 2 2 11 1 2 1 1]]]]]]]

pncn cn p cn ppnc c p c ppnc c p c ppcZ Z ZZ Z ZZ Z ZZ...... ... ... .........2 12 2 2 2 11 1 2 1 1]]]]]]

cncn cn c cn ccnc c c c ccnc c c c cccZ Z ZZ Z ZZ Z ZZ...... ... ... .........2 12 2 2 2 11 1 2 1 1]]]]]]]

cnpn pn c pn ccnp p c p ccnp p c p ccpZ Z ZZ Z ZZ Z ZZ...... ... ... .........2 12 2 2 2 11 1 2 1 112/27/09 12/27/09 Michael Elsdon Michael Elsdon 38 38

++ + 2 /2 /2 /2 /0 022 20) cos( ) cos( ) cos( ) cos(wp ypwp ypwc ycwc ycm nyn xmc p c yn c xm p yn p xmn mc ppck k kdW dW y k x k y k x kW abW h jZInteraction between ports Interaction between portspport s1s egm entl1w2c port s]]]]]]]

pncn cn p cn ppnc c p c ppnc c p c ppcZ Z ZZ Z ZZ Z ZZ...... ... ... .........2 12 2 2 2 11 1 2 1 112/27/09 12/27/09 Michael Elsdon Michael Elsdon 39 39

c ports1segmentl2Wp portspport s1segmentl1w2cport s++==Step 2: Alpha and Beta Sections RecombinedStep 2: Alpha and Beta Sections Recombined to form gamma segmentto form gamma segment ]]]

]]]

01121 cp ccpc pp pZ ZZ Z Zl3 = L - l2l2w2segment1pportspportsp port]]]]]]

0 0 0 1 1 0 0 00 0 1 0 0 1 0 00 1 0 0 0 0 1 01 0 0 0 0 0 0 11]]]]]]

0 0 0 1 1 0 0 00 0 1 0 0 1 0 00 1 0 0 0 0 1 01 0 0 0 0 0 0 12]]]]]]

0 0 0 0 0 0 0 00 0 0 0 0 0 0 00 0 0 0 0 0 0 00 0 0 0 0 0 0 0012/27/09 12/27/09 Michael Elsdon Michael Elsdon 40 40LWl1w1l2l2w2w2s eg me n tl3 = L - l2l2w2segment1c portsc portsp portl2l3 = L - l2w2segment2c portsc portsp port++==]]]

]]]

01121 cp ccpc pp pZ ZZ Z ZStep 3: Gamma Segments Recombined Step 3: Gamma Segments Recombinedto form original patch structure to form original patch structure12/27/09 12/27/09 Michael Elsdon Michael Elsdon 41 41

Real Input Impedance v Frequency01002003004005006007002.8 2.82 2.84 2.86 2.88 2.9 2.92 2.94 2.96 2.98 3Frequency, GHzReal Input Impedance,Imaginary Input Impedance v Frequency-400-300-200-10001002003004002.8 2.82 2.84 2.86 2.88 2.9 2.92 2.94 2.96 2.98 3Frequency, GHzImaginary Input Impedance,Simulated and Practical ResultsSimulated and Practical Results0010 11log 20Z ZZ ZSinin+Simulated SimulatedMeasured Measured1 101 10) ( 1120) ( 11+dB SdB SVSWR*Z0=50ZinVSWRBW = 1.32%BW = 1.25%Res. FreqImag(Zin)=012/27/09 12/27/09 Michael Elsdon Michael Elsdon 42 42Simulated and Practical ResultsSimulated and Practical ResultsModellingTechniqueResonantFrequency(GHz)InputImpedance()VSWR BW%(2:1)Segmentation 2.836 650 1.25Practical 2.856 625 1.32Reasons for Differences Reasons for Differences Manufacturing Tolerances Approximation of fringing field extension Dielectric properties of PCB not accurately defined12/27/09 12/27/09 Michael Elsdon Michael Elsdon 43 43

Effect of Slot Dimensions on Antenna DesignImportant Performance Characteristics: (from circuit viewpoint) OperatingFrequency InputImpedance BandwidthImportant Performance Characteristics: (from far-field viewpoint) Radiation Pattern Polarisation Gain BeamwidthFOCUS OF THIS INVESTIGATION12/27/09 12/27/09 Michael Elsdon Michael Elsdon 44 44

LWLsws/2xsysws/2syLmWmDefinition of Slot ParametersSlot Length (Ls),Slot Width (Ws), Slot Position (Xs), SlotSlot Length (Ls),Slot Width (Ws), Slot Position (Xs), Slot Position (Ys) Position (Ys)12/27/09 12/27/09 Michael Elsdon Michael Elsdon 45 45

Real Input Impedance v Frequency01002003004005006007008002.772 2.82 2.868 2.916 2.964Frequency, GHzLs = 4mmLs = 8mmLs = 12mmReal Input Impedance510602683Effect of Increasing Slot Length KEYFEATURES SMALL frequency reduction of 0.1GHzIncreased Input Impedance12/27/09 12/27/09 Michael Elsdon Michael Elsdon 46 46

Return Loss v Frequency-40-35-30-25-20-15-10-502.78 2.828 2.876 2.924Frequency, GHzReturn Loss, dBLs = 4mmLs = 8mmLs = 12mmBW = 0.962%BW = 0.845%BW = 0.712%KEYFEATURE KEYFEATURE SMALL bandwidthSMALL bandwidth reduction reduction 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 47 47Real Input Impedance v Frequency01002003004005006002.76 2.832 2.904 2.976 3.048 3.12 3.192Frequency, GHzWs = 4mmWs = 8mmWs = 12mmReal Input Impedance345406527Effect of Increasing Slot WidthKEYFEATURES KEYFEATURESSIGNIFICANT Frequency reduction ofSIGNIFICANT Frequency reduction of 0.3GHz 0.3GHzSIGNIFICANTLY increased inputSIGNIFICANTLY increased input ImpedanceImpedance 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 48 48Return Loss v Frequency-45-40-35-30-25-20-15-10-502.76 2.832 2.904 2.976 3.048 3.12 3.192Frequency, GHzReturn Loss, dBWs = 4mmWs = 8mmWs = 12mmBW = 1.5%BW = 1.318%BW = 0.968%KEYFEATURE KEYFEATURESIGNIFICANT bandwidth reduction SIGNIFICANT bandwidth reduction 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 49 49Effect of Increasing Slot Position (Xs)Real Input Impedance v Frequency01002003004005006002.9 2.948 2.996 3.044 3.092 3.14 3.188 3.236Frequency, GHzXs = 3mmXs = 7mmXs = 11mmXs = 15mmReal Input Impedance

427505521470KEYFEATURES KEYFEATURESSIGNIFICANT frequency reduction ofSIGNIFICANT frequency reduction of 0.24GHz 0.24GHzMARGINAL effect on input Impedance MARGINAL effect on input Impedance 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 50 50

Return Loss v Frequency-45-40-35-30-25-20-15-10-502.92 2.968 3.016 3.064 3.112 3.16Frequency, GHzReturn Loss, dBXs = 3mmXs = 7mmXs = 11mmXs = 15mmBW = 1.65%BW = 1.299% BW = 1.202%BW = 1.083%KEYFEATURE KEYFEATURESIGNIFICANT bandwidth reduction SIGNIFICANT bandwidth reduction 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 51 51Real Input Impedance v Frequency01002003004005006002.8 2.848 2.896 2.944 2.992 3.04 3.088 3.136 3.184Frequency, GHzsy = 0mmsy = 5mmsy = 10mmReal Input Impedance

390470500Effect of Increasing Slot Position (Ys)KEYFEATURES KEYFEATURESSMALL frequency reduction of 0.1GHz SMALL frequency reduction of 0.1GHzSIGNIFICANTLY increased inputSIGNIFICANTLY increased input Impedance Impedance12/27/09 12/27/09 Michael Elsdon Michael Elsdon 52 52Return Loss v Frequency-40-35-30-25-20-15-10-502.8 2.848 2.896 2.944 2.992 3.04 3.088Frequency, GHzReturn Loss, dBsy = 0mmsy = 5mmsy = 10mm

BW = 1.311%BW = 1.083% BW = 0.978%KEYFEATURE KEYFEATURESMALL bandwidth reductionSMALL bandwidth reduction 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 53 53

Variable Frequency Zin BandwidthWs f01 Zin01 BW01Ls(Ls < L/2) (L/2 < Ls < 3L/4) (Ls > 3L/4)f01 f01 f01 Zin01Zin01Zin01BW01BW01BW01xs(xs < L/4)(L/4 < xs < L/2)(L/2 < xs < 3L/4)(xs > 3L/4) f01f01f01f01Zin01Zin01Zin01Zin01BW01BW01BW01BW01ys(ys < L/2)

(ys < L/2) f01f01Zin01Zin01BW01BW01

SUMMARYEffect of Slot Parameters on Performance of TM01 Mode12/27/09 12/27/09 Michael Elsdon Michael Elsdon 54 54Major OutcomesOperation Operation Placement of Slot effects different TMmn modes Slot width largely effects characteristics of TM0n modes Slot length has most effect on TMm0modesMost Significant Trade-Offs Most Significant Trade-Offs Increased Input Impedance difficulty in feeding Reduced Bandwidth12/27/09 12/27/09 Michael Elsdon Michael Elsdon 55 55Design of Reduced Size Patch Antennas Design Goals Design GoalsMaximum Frequency reduction for a given patch sizeMaintain Input Impedance of practical valueMaximise Impedance Bandwidth Challenges ChallengesSignificant trade-offs between these performance parameters Not possible to simultaneously optimise each oneDesigner must therefore achieve BEST patch structure for given application 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 56 56BASIC PATCH ANTENNA: Current Distribution of TM01 modeDesign based on modification of TM01 mode12/27/09 12/27/09 Michael Elsdon Michael Elsdon 57 57

12/27/09 12/27/09 Michael Elsdon Michael Elsdon 58 58LWLsws/2xsysws/2syswfFeed pointFinal DesignFinal Design12/27/09 12/27/09 Michael Elsdon Michael Elsdon 59 59ProposedDesign Reference Antenna*ResonantFrequency, GHz 2.45 2.45Size Reduction, % 55 0Return Loss, dB -23 -29VSWR Bandwidth, % 1.22 1.904Input Impedance, 50 330Measured Gain, dB 5.8 6.1Patch Length L mm 30 39.4Practical ResultsPractical Results*Reference Antenna: Conventional Rectangular PatchPerformance Summary Performance Summary55% Size ReductionInput Impedance of 50 Reduced VSWR Bandwidth 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 60 60Previous design Previous design Operates by modification of TM01mode Limitation: Limitation: Impedance matching network is requiredNew Structure: New Structure: Operates by creating an additional TM0 modeAdvantages: Advantages: Has input impedance of 50 Can use direct feed No impedance matching required Design based on Creation of TM0 mode12/27/09 12/27/09 Michael Elsdon Michael Elsdon 61 61Two New Antenna DesignsFeedpointLWl1w1ssl1w1ErhDesign A Design ADESIGN A DESIGN ACreates new TM Creates new TM0 0 mode bymode by insertionof two slots close toinsertionof two slots close to non-radiating edge non-radiating edgeSlot dimensions and positionSlot dimensions and position control frequency and inputcontrol frequency and input impedance impedance12/27/09 12/27/09 Michael Elsdon Michael Elsdon 62 62Typical Current PathsTM01 mode (f=3.19GHz) TM0 mode (f=2.86GHz)TM TM0 0 mode has different current path to TM mode has different current path to TM01 01 mode modeTM TM0 0 mode has different frequency and impedancemode has different frequency and impedance response response12/27/09 12/27/09 Michael Elsdon Michael Elsdon 63 63Two New Antenna DesignsDESIGN B DESIGN BIncorporates additional slot inIncorporates additional slot in centre centreIncreases current path of TM Increases current path of TM0 0 mode modeGreater Size Reduction Greater Size ReductionFeedpointLWl1w1s1s1l1w1l2w2ErhsFeedpointLWl1w1ssl1w1ErhDesign A Design ADesign B Design BDESIGN A DESIGN ACreates new TM Creates new TM0 0 mode bymode by insertionof two slots close toinsertionof two slots close to non-radiating edge non-radiating edgeSlot dimensions and positionSlot dimensions and position control frequency and inputcontrol frequency and input impedance impedance12/27/09 12/27/09 Michael Elsdon Michael Elsdon 64 64Key Design FeaturesPrimary Performance Goals: Primary Performance Goals:Resonant frequency Resonant frequencyInput impedance Input impedanceBandwidth BandwidthGeneral Conclusions on patch design: General Conclusions on patch design:Slot Separation:results more predictable when slots this isSlot Separation:results more predictable when slots this is kept low kept lowSlot Width:for a given slot length, Zin increases with slotSlot Width:for a given slot length, Zin increases with slot width widthThus Zin Ws should be small Thus Zin Ws should be smallSlot Length: Controls resonant frequency and input impedance Slot Length: Controls resonant frequency and input impedanceControllingParameters: ControllingParameters:Slot Length Slot LengthSlot Width Slot WidthSlot Position Slot PositionNO UNIQUE SOLUTION FOR PATCH DESIGNNO UNIQUE SOLUTION FOR PATCH DESIGN12/27/09 12/27/09 Michael Elsdon Michael Elsdon 65 65Design ADesign BFinal DesignsFinal Designs12/27/09 12/27/09 Michael Elsdon Michael Elsdon 66 66-40-35-30-25-20-15-10-502.32.352.38 2.412.46 2.53 2.632.722.772.782.832.882.953.053.15 3.25Freq, GHzreturn loss, dBDesign BDesign AReferencePractical ResultsPractical Results*Reference Antenna: Conventional Rectangular Patchwith impedance matching network12/27/09 12/27/09 Michael Elsdon Michael Elsdon 67 67DesignA DesignB Reference AntennaResonantFrequency, GHz 2.778 2.338 3.15Size Reduction, % 12 40 NAReturn Loss, dB -16.5 -35 -35VSWR Bandwidth, % 1.25 1.4 1.904Input Impedance, 50 50 330Measured Gain, dB 4.2 3.7 6.1Practical ResultsPractical Results*Reference Antenna: Conventional Rectangular Patchwith impedance matching networkPerformance Summary Performance Summary12% and 40% Size Reduction respectively No Impedance matching n/w required Reduced VSWR BandwidthReduced Gain 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 68 68EXTENSION: Planar Fed Dual Frequency DesignLWw1s1l1w1wflfZins12/27/09 12/27/09 Michael Elsdon Michael Elsdon 69 69Practical Resultsf1GHzf2GHzResonant Frequency, GHz 3.18 3.51Return Loss, dB -38 -18.6VSWR Bandwidth, % 1.57 0.41Input Impedance, 50 50Gain, dB 5.9 5.112/27/09 12/27/09 Michael Elsdon Michael Elsdon 70 70Practical Results-45-40-35-30-25-20-15-10-5033.063.123.183.243.33.363.423.483.543.63.663.723.783.843.93.96Freq, GHzReturn Loss, dBf1f2Dual Frequency Operation achieved by operating using TM01 and TM0 modesImpedance Matching at both frequencies achieved using inset feed12/27/09 12/27/09 Michael Elsdon Michael Elsdon 71 71Reduced Size Designs with Circular Reduced Size Designs with Circular PolarisationPolarisationApplication of Slot Loading to Nearly Square CP PatchApplication of Slot Loading to Nearly Square CP Patch Antenna Antenna EMANIM.lnk EMANIM.lnk12/27/09 12/27/09 Michael Elsdon Michael Elsdon 72 72Linear and Circular PolarisationLinear and Circular Polarisation( )z yt E E sin2Linear Polarisation Linear PolarisationCircular Polarisation Circular Polarisation( )z xt E E sin1( ) + z yt E E sin2yxzE2Amplitude of yAmplitude of y fields fieldsPhase shift in zPhase shift in z direction directionPhase difference between E Phase difference between E1 1 and E and E2 2For CP For CPE E1 1 = E = E2 2 = 90 = 900 012/27/09 12/27/09 Michael Elsdon Michael Elsdon 73 73Generation of Circular PolarisationGeneration of Circular PolarisationDual FeedDual FeedLLPatchAntennaFeed NetworkPrinciple of Operation Principle of Operation Two adjacent sides of square patch are fed to excite TM Two adjacent sides of square patch are fed to excite TM01 01 and TM and TM10 10modes modesFeed network ensures equal amplitude split and 90 Feed network ensures equal amplitude split and 900 0 phasephase difference between two modes difference between two modesLLPatchAntennaFeed NetworkEMANIM.lnk EMANIM.lnk12/27/09 12/27/09 Michael Elsdon Michael Elsdon 74 74Generation of Circular PolarisationGeneration of Circular PolarisationSingle FeedSingle FeedPrinciple of Operation Principle of Operation TM TM01 01 and TM and TM10 10 modes having slightly different frequencies modes having slightly different frequencies TM TM01 01 mode leads by +45 mode leads by +450/0/ TM TM10 10 mode lags by -45 mode lags by -450 0dl is controls phase shift between two modes dl is controls phase shift between two modes12/27/09 12/27/09 Michael Elsdon Michael Elsdon 75 75Basic Reduced Size CP Patch Antenna DesignDesign Goals Design Goals Maximum Frequency ReductionInput Impedance MatchingWide Impedance BandwidthMinimize Axial RatioMaximise Axial Ratio BandwidthMaximise perturbation segmentTrade-offs with sizeTrade-offs with size reduction reductionReduced perturbation size (dl)Increased input impedanceReduced axial ratio bandwidthl1w1LL+dlFeedpointBasic Slot Loaded Design12/27/09 12/27/09 Michael Elsdon Michael Elsdon 76 76l2w2l1w1LL+dll3FeedpointDesign 1Improved Reduced Size CP Patch Antenna Design12/27/09 12/27/09 Michael Elsdon Michael Elsdon 77 77l1mmdlmm FrequencyGHzInputImpedanceCPBW%0 0.81 2.95 245 1.54 0.81 2.94 250 1.48 0.71 2.826 290 1.212 0.51 2.643 330 1.116 0.41 2.409 475 1.1l1 mmdlmm FrequencyGHzInputImpedanceCPBW%0 0.71 2.95 310 1.24 0.71 2.925 330 0.928 0.61 2.805 400 0.712 0.41 2.639 750 0.5916 0.21 2.396 1200 0.49New DesignReference AntennaAdvantages Advantages Larger Perturbation segmentRelaxed TolerancesGreater Axial Ratio bandwidthLower Input ImpedanceGreater Practical Size reduction12/27/09 12/27/09 Michael Elsdon Michael Elsdon 78 78ContributionsContributionsRigorous Investigation of Slot Loaded PatchRigorous Investigation of Slot Loaded Patch Antennas AntennasApplication of segmentation modelling to these structuresApplication of segmentation modelling to these structures Determined relationship between slot parameters andDetermined relationship between slot parameters and antenna performance antenna performanceHighlighted associated trade-offs Highlighted associated trade-offsProposed, Designed and Implemented new PlanarProposed, Designed and Implemented new Planar Fed Reduced Size Antenna Design Fed Reduced Size Antenna DesignLinear Polarised Antenna using TM Linear Polarised Antenna using TM01 01 modemode Linear Polarised Antenna using TM Linear Polarised Antenna using TM0 0 mode modeCircular Polarised Antenna using TM Circular Polarised Antenna using TM01 01 / TM / TM10 10 mode modeDual Frequency LP antenna using TM Dual Frequency LP antenna using TM01 01 and TM and TM0 0 modes modes12/27/09 12/27/09 Michael Elsdon Michael Elsdon 79 79Publications and Presentations:1. M. Elsdon, A. SambellandS. Gao, InsetMicrostrip-lineFedDualFrequency MicrostripPatchAntenna,12thInternationalConferenceonAP, Exeter, England,No. 491, Volume1, pp28-30, 31stMarch 3rd April 20032. M. Elsdon, A. SambellandS. Gao, NovelCompactHarmonic-SuppressedPlanar-FedMicrostripAntenna, 5th EuropeanPersonalMobileCommunicationsConference, Glasgow, Scotland, No. 492, pp1-4, 22nd 25th April2003 3. M. Elsdon, A. Sambell, S. GaoandY. Qin, CompactCircularPolarisedPatchAntennawithRelaxedManufacturingToleranceandImprovedAxialRatioBandwidth, IEEElectronicLetters, Volume39, No. 18, p1296-1298, 4th September2003 4. Y. Qin, S. Gao, A. Sambell, E. KorolkewiczandM. Elsdon, BroadbandPatchAntennawithRingSlotCoupling, IEEElectronicLetters, Volume40, No. 1, pp5-6, 8th January 20045. M. Elsdon, A. Sambell, S. GaoandY. Qin, PlanarFedCompactCircularPolarisedMicrostripAntennawithTriangularSlotLoading, MicrowaveandOpticalTechnologyLetters, Issue41:3, pp226-228, 5th May 20046. D. Smith, M. Leach, M. Elsdon and S. J. Foti, Using Invisible Region Wave Vectors For Determining The Properties Of Microwave Antennas And Imaging Fields, 4th Int. Symp. On Communication Systems, Networks And Digital Signal Processing, CSNDSP-04, Newcastle UK, pp. 248-251, July 2004.12/27/09 12/27/09 Michael Elsdon Michael Elsdon 80 80Publications and Presentations:7. D. Smith, M. Leach, M. Elsdon and S. J. Foti, Imaging Of Concealed Objects From Scalar Microwave Holograms, RF and Microwaves Conf., RFM-04 Malaysia, pp. 127-131, Oct. 2004.8. D. Smith, M. Leach, M. Elsdon and S. J. Foti, Holographic Reconstruction of Dish Antenna Measurements, Int. Symp. On Antennas, JINA-04, Nice France, pp. 308-309, Nov. 2004.9. L.S.K. Dampanaboina, D. Smith, M. Leach, M. Elsdon, S.J. Foti, Microwave Antenna Imaging for Medical Diagnostics, Britains Top Young Engineers Competition, House of Commons, LONDON, 14th Dec. 2004.10.Y. Qin, S. Gao, M. ElsdonandA. Sambell, BroadbandhighefficiencyactiveantennaforRFFront-Endapplication, IEEEAsiaPacificMicrowaveConference2005.11. D. Smith, M. Leach, M. Elsdon and S. J. Foti, ImagingDielectricObjectsfromScalarIntensityPatternsbymeansofIndirectHolography, IEEEAP-SInternationalSymposiumandUSNC / URSINationalRadioScienceMeeting, pp?-?, July200512. M. Elsdon, A. Sambell, andY. Qin, ReducedSizeDirectPlanarFedPatchAntenna, IEEElectronicLetters, Volume41, No. 16, p884-886, 4th Aug. 2005 12/27/09 12/27/09 Michael Elsdon Michael Elsdon 81 81Publications and Presentations:13. D. Smith, M. Leach, M. Elsdon, M.J. Fernando and S. J. Foti, Imaging Of Dielectric Objects Reconstructed Using Indirect Holographic Intensity Patterns, 9th International Conference on Electromagnetics in Advanced Applications (ICEAA 05), pp401-404, Sept. 12-16, 2005, Torino, Italy 14. M. Elsdon,Microwave Imaging using Indirect SyntheticReference Beam Holography, InvitedLecture, Calgary University, December2005.15.M. J. FDO, M. Elsdon, M. Leach, D. Smith, S.J. Foti, Breast Cancer Detection using Microwave Holographic Imaging, Britains Top Young Engineers Competition, House of Commons, LONDON, Dec. 2005.16. Y. Qin, S. Gao, A. Sambell, M. Elsdon, andE. Korelkiewicz, DesignofaBroadbandSquareRingSlotCoupledPatchAntenna, MicrowaveandOpticalTechnologyLetters, Issue47:5,200517. M. Elsdon, D. Smith, M. Leach. S. Foti, Microwave ImagingofConcealedMetalObjectsusingaNovelIndirectHolographicMethod, MicrowaveandOpticalTechnologyLetters, Issue47:6, December 200518. M. Elsdon, M. Leach, D. Smith, S. Foti, Microwave Imaging at Northumbria University, MIAS-IRC Spring School, OxfordUniversity, 19 24th March 2006.12/27/09 12/27/09 Michael Elsdon Michael Elsdon 82 82Publications and Presentations:19. M. Elsdon, D. Smith, M. Leach. S. Foti, Experimental Investigation of Breast Tumor Imaging Using Indirect Microwave Holography, MicrowaveandOpticalTechnologyLetters, Issue48:3, March 200620. D. SmithandM. Elsdon, BreastCancerdetectionusingMicrowaveHolography, InvitedLecture, NewcastleUniversityMedicalSchool, May15th 2006.21. M. Elsdon, andY. Qin, Dual Frequency PlanarFedMicrostrip PatchAntenna, MicrowaveandOpticalTechnologyLetters, Issue48:6, pp1053-1054, June 200622. D. Smith, M. Leach, M. Elsdon, S.J. Foti, Indirect Holographic Techniquesfor Determining Antenna Radiation Characteristics and Imaging Aperture Fields, IEEEAntennasandPropagationMagazine, accepted, 200623. M. Leach, M. Elsdon, S.J. Foti and D.Smith, Imaging Dielectric ObjectsUsing a Novel Synthetic Off-Axis Holographic Technique, Microwave and Optical Technology Letters, accepted 200624. M. Elsdon, M. Leach, M.J. FDO, S.J. Foti, D. Smith, Early Stage Breast Cancer Detection using Indirect Microwave Holography, EuropeanMicrowave Conference, Manchester,pp?-?, September 10-15 200612/27/09 12/27/09 Michael Elsdon Michael Elsdon 83 83Publications and Presentations:25. D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S. J. Foti, 3DMicrowave Imaging for Medical and Security Applications, InternationalRFandMicrowaveConference,

pp?-?, Malaysia,Sept. 12-14 200626.D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S. J. Foti, Medical Imaging using a Microwave Indirect Holographic Technique, Mediterranean Microwave Symposium, Genoa, pp?-?,September 19-21 200627. M.J. Fdo, M. Elsdon, M. Leach, D. Smith, S.J. Foti, A Holographic Solution forConcealed Object Detection, The Mediterranean Journal of Computers andNetworks, Vol. 4, No. 2, pp. 160-165, October 2006. 28. D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S. J. Foti, A Method for 3D Breast Cancer Imaging Using Microwave Holography, InternationalSymposiumonAntennas andPropagation, Singapore,pp?-?,November 1-4 200629. D. Smith, M. Elsdon, M. Leach, M.J. Fdo, S. J. Foti, A Microwave Indirect Holographic System for Security and Medical Imaging Applications, European ConferenceonAntennasandPropagation, France, pp?-?,November 6-10200612/27/09 12/27/09 Michael Elsdon Michael Elsdon 84 84AcknowledgementsAcknowledgementsProf. A Sambell: Director of Studies Prof. B. Cryan: 2nd SupervisorDr. D. Smith: 2nd SupervisorProf. S. Foti: for advice and fruitful discussions12/27/09 12/27/09 Michael Elsdon Michael Elsdon 85 85Thank You for Your Thank You for Your AttentionAttention12/27/09 12/27/09 Michael Elsdon Michael Elsdon 86 86ResonantResonant Frequency FrequencyInput Impedance at Resonance Input Impedance at ResonanceImportant Design Important Design ConsiderationsConsiderations rinGZ212 221

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