Modeling of a Half-wave Monopole Antenna - Educypedia
Modeling of a Half-wave Monopole Antenna - Educypedia
Modeling of a Half-wave Monopole Antenna - Educypedia
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<strong>Modeling</strong> <strong>of</strong> a <strong>Half</strong> <strong>wave</strong><br />
<strong>Monopole</strong> <strong>Antenna</strong> on a<br />
Florida EME Research Lab<br />
portable radio<br />
S. L. Ooi<br />
Motorola Florida Corporate Research Labs<br />
8000 West Sunrise Blvd<br />
Plantation<br />
FL 33324<br />
sooliam.ooi sooliam ooi@motorola motorola.com .com<br />
Motorola Confidential Proprietary 3 November 2000
Why <strong>Antenna</strong> <strong>Modeling</strong>?<br />
Predict the antenna characteristics<br />
• radiation pattern<br />
• impedance<br />
SL Ooi<br />
Opportunity for improvement<br />
• find the best matching<br />
• re-tuning the antenna<br />
• effect <strong>of</strong> placement <strong>of</strong> surrounding mechanical parts,<br />
e.g. shields, speaker, chassis length,etc.<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 2
Summary<br />
Modeled the whip antenna on both ground plane and<br />
chassis.<br />
Accurate S11 prediction was obtained.<br />
Challenges<br />
• Geometry information on drawing incomplete.<br />
• Material property information not readily available.<br />
• minimum information obtained from vendor.<br />
• Information obtained by breaking down samples.<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 3
New Radio, new <strong>Antenna</strong><br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 4
New <strong>Antenna</strong> for New Band<br />
SL Ooi<br />
• Old Frequency 806 - 870 MHz<br />
• New Frequencies 765 - 870 MHz<br />
• Center frequency 815 MHz.<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 5
Proposed sample longer than original<br />
SL Ooi<br />
Original length=170 mm<br />
Reducing the center frequency<br />
Adding length = new tooling = $$$$$ + Cycle Time<br />
Proposed length= 180 mm<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 6
<strong>Antenna</strong> Design<br />
SL Ooi<br />
Feeding coil<br />
<strong>Half</strong>-<strong>wave</strong> whip, enclosed in polyurethane jacket.<br />
Polycarbonate cylinder<br />
Conductive tape around<br />
the feeding coil.<br />
Circular<br />
holder<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 7
antenna model<br />
SL Ooi<br />
Polyurethane<br />
coating<br />
εr=3.6<br />
Polycarbonate<br />
housing with<br />
tuning<br />
conductive<br />
tape<br />
Steel cable<br />
Base-loading<br />
coil<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 8
First Stage<br />
SL Ooi<br />
Model the existing antenna<br />
sample on ground plane<br />
to establish correlation.<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 9
Model on ground plane<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 10
Dummy Cylinders to enhance meshing<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 11
Feeding Structure - port and cap<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 12
Matching conductive tape<br />
Modeled by PEC boundary condition<br />
SL Ooi<br />
on the polycarbonate cylinder.<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 13
Impedance on ground plane(S11)<br />
SL Ooi<br />
Ground plane MeasuredSimulated<br />
Center frequency 805.2 806.1<br />
Lower S11@-10dB 770.7 772.1<br />
Higher S11@-10dB 841.8 838.4<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 14
Stage 2<br />
SL Ooi<br />
Model the antenna on the<br />
radio chassis.<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 15
Radio model<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 16
Full model<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 17
Radio chassis S11<br />
SL Ooi<br />
Chassis MeasuredSimulated<br />
Center frequency 813.6 816.3<br />
Lower S11@-10dB 760 775.5<br />
Higher S11@-10dB 852.2 845<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 18
Measured S11 on Chassis<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 19
Feeding, knobs and switches<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 20
Radiation patterns<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 21
Stage 3<br />
SL Ooi<br />
Use the original length <strong>of</strong> 170 mm,<br />
conduct parametric sweep<br />
varying the width <strong>of</strong> the<br />
conductive tape.<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 22
Varying the width <strong>of</strong> the conductive tape.<br />
<strong>Antenna</strong> at original length <strong>of</strong> 170 mm.<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 23
Final, production version<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 24
Final products - XTS2500 Radios<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 25
Benefit<br />
• Complete understanding <strong>of</strong> the<br />
antenna.<br />
• Track changes, and possible drift in<br />
performance.<br />
• Check for impact <strong>of</strong> future changes <strong>of</strong><br />
radio mechanics and metal part<br />
placement.<br />
SL Ooi<br />
Ans<strong>of</strong>t HF Workshop 25th Feb 2002 26
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