design of dielectric probe for near-field measurement
design of dielectric probe for near-field measurement
design of dielectric probe for near-field measurement
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DESIGN OF DIELECTRIC PROBE FORNEAR-FIELD MEASUREMENTQian Qiaoyuan and Wen Mo *Shanghai Spaceflight Institute <strong>of</strong> TT&C and TelecomShanghai, China
OutlineIntroductionPattern CharacteristicsRCS CharacteristicsCross-Polarization DesignDielectric Probe with Waveguide FeedSummarySHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
1. Introduction (Ⅱ)The <strong>probe</strong> should have• Low RCS -- Lower multiple reflection error• Same E/H plane pattern -- Uni<strong>for</strong>m response <strong>for</strong> waves fromdifferent directions• Low cross-polarization -- Only one scan is needed <strong>for</strong> onepolarization <strong>measurement</strong>SHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
2. Pattern Characteristics (Ⅰ)The Dielectric Rod ProbeDielectric Rod ConfigurationSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
2. Pattern Characteristics (Ⅱ)00E pl aneE pl ane-5H pl ane-5H pl aneAmpl i t ut e ( dB)-10-15-20Ampl t ude ( dB)-10-15-20c-25-25-30- 60 - 40 - 20 0 20 40 60Azi mut h ( deg)Far-Field Pattern <strong>of</strong> theDielectric Probe, E/H plane cut (18 GHz)-30- 60 - 40 - 20 0 20 40 60Azi mut h ( deg)Far-Field Pattern <strong>of</strong> theDielectric Probe , E/H plane cut (20 GHz)SHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
2. Pattern Characteristics (Ⅲ)Far-Field Pattern <strong>of</strong> the Dielectric Probe (Taper Edged Waveguide)SHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
3. RCS Characteristics (Ⅰ)• Lower multiple reflection error → Low RCS <strong>of</strong> <strong>probe</strong>• RCS control:• Proper Material -- Dielectric material• Proper Shape and Dimension -- Rod ShapeSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
3. RCS Characteristics (Ⅱ)(a) E Plane(b) H PlaneRCS SimulationRCS Simulation Result <strong>of</strong>the Dielectric Probe (18GHz)SHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
3. RCS Characteristics (Ⅳ)The Dielectric Rod Probe with Rectangular EdgeThe Dielectric Rod Probe with Tapered EdgeSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
3. RCS Characteristics (Ⅴ)RCS Measurement Result <strong>of</strong> the Dielectric Probe(Tapered Edge Waveguide)Black line - waveguide only without <strong>dielectric</strong> rodBlue line - complete <strong>probe</strong> with <strong>dielectric</strong> rodSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
3. RCS Characteristics (Ⅵ)Gated OutPosition <strong>of</strong> Time-GateSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
4. Polarization Design (Ⅰ)With no cross-polarization <strong>of</strong> the <strong>probe</strong>→ Only one scan is needed <strong>for</strong> a single-polarization antenna<strong>measurement</strong>v v v vE( θ, ϕ) E′ ( θ, π- ϕ)- E( θ, ϕ) E ′( θ, π- ϕ)=θ θ ϕ ϕ∞ ∞ rC cosθexp( jkz cosθ) g P ( )exp( jkx si nθcosϕ+jky si nθsi n ϕ)dx dy∫ ∫0−∞ −∞B 0 0 0 0 0SHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
4. Polarization Design (Ⅱ)EM Field Changes vs. StructureChange <strong>of</strong> the WaveguideEM Field Changes at the Feed<strong>of</strong> the Dielectric RodEM Field changes at the End<strong>of</strong> the WaveguideSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
4. Polarization Design (Ⅲ)Far-<strong>field</strong> amplitude <strong>of</strong> 8x8G test20060103Probe-1.nsiFar-<strong>field</strong> amplitude <strong>of</strong> 8x8G test20060103Probe-1.nsi0main polcross pol0main polcross pol-5-5-10-10-15-15Amplitude (dB)-20-25-30Amplitude (dB)-20-25-30-35-35-40-40-45-45-50-50 -25 0 25 50Elevation (deg)-50-50 -25 0 25 50Azimuth (deg)(a) E plane(b) H planeMain/Cross Polarization Pattern<strong>of</strong> the Dielectric ProbeSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
5. Dielectric Probe with Waveguide Feed (Ⅰ)50-526GHz30GHz36GHz5-526GHz36GHz30GHzAplitute (dB)-10-15-20-25-30-3540GHzAmpi t ut e ( dB)-15-25-35-4540GHz-40- 180 - 150 - 120 - 90 - 60 - 30 0 30 60 90 120 150 180-55- 180 - 150 - 120 - 90 - 60 - 30 0 30 60 90 120 150 180Azi mut h ( deg)Azi mut h ( deg)Dielectric Rod Probe Fed byRectangular Waveguide(a) E planePattern <strong>of</strong> Dielectric Rod ProbeFed by Rectangular Waveguide(b) H planeSHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
5. Dielectric Probe with Waveguide Feed (Ⅱ)(a) E plane(b) H planeCross-polarization Pattern Simulation Results (30GHz)SHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
6. Summary• The square waveguide fed <strong>dielectric</strong> <strong>probe</strong> has low RCS, symmetricpattern, relatively high gain and low cross-polarization pattern.• Its only disadvantage is that the deep drops in the front pattern,which needs to be improved by further optimal work.• Another rectangular <strong>probe</strong> <strong>design</strong> is also good at low RCS and lowcross-polarization.SHANGHAI SPACEFLIGHT INSTITUTE OF TT&C AND TELECOM, CHINA
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