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Antennas -- in 60 Minutes or Less!

Antennas -- in 60 Minutes or Less!. Cynthia Furse Department of Electrical and Computer Engineering University of Utah cfurse@ece.utah.edu. Antennas 101. Size / current distribution Radiation Pattern (“far”fields) Directivity Gain Side Lobes Polarization Near Fields Mutual Coupling

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Antennas -- in 60 Minutes or Less!

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  1. Antennas -- in 60 Minutes or Less! Cynthia Furse Department of Electrical and Computer Engineering University of Utah cfurse@ece.utah.edu

  2. Antennas 101 • Size / current distribution • Radiation Pattern (“far”fields) • Directivity • Gain • Side Lobes • Polarization • Near Fields • Mutual Coupling • Specific Absorption Rate (SAR) • Input Impedance (matching) • Link Budget

  3. Dipole Antenna Current distribution From:http://www.qth.com/antenna/dipole.gif,plot.gif

  4. Radiation Pattern Direction of Maximum Dipole Radiation Direction of Maximum IsotripicRadiation Radiation Pattern Of an ISOTROPIC Radiator (that doesn’t Exist) Directivity = Pmax dipole / Pmax Isotropic = 1.67 Gain = Directivity * Efficiency

  5. Why do we care about Gain? Link Budget

  6. 3dB (1/2 Power Point) Half Power Beam Width (HPBW) Half Power Beam Width (HPBW)

  7. Monopole Antenna Capacitive Load Monopole Helix Ground From:http://www.letstalk.com//Images/5-a.gif

  8. Specific Absorption Rate (SAR) FCC (ANSI/IEEE) Regulation SAR (1g average) <1.6 W/kg

  9. Cellular Telephones SAR Distribution in Adult - 835 MHz - Simplified Phone Model - l /4 antenna Pandit,McDermott,Lazzi,Furse,Gandhi, “Electrical Energy Absorption in the Human Head,” presented at IEEE Visualization ‘96, S.F., CA 1996

  10. SAR Distributions - 835 MHz (adult, 10 year old, 5 year old) 10 year old Adult 5 year old From: Gandhi, Lazzi, Furse, IEEE Trans. MTT 44(10) 1996

  11. Folded Dipole From:http://www.qth.com/antenna/fdipole.gif

  12. Monopole Antenna above Ground =Dipole Antenna Ground

  13. MEANDER LINE ANTENNAS

  14. RADIATION PATTERN OF MEANDER LINE ANTENNA

  15. Microstrip Antenna(Slot of Same Size would give identical results From: http:// www.centurion.com

  16. Genetic Algorithm • Choose “Gene” Parameters • Randomly create population • “Survival of the Fittest” • Gene “Crossover” and “Mutation” • Statistically Optimal N

  17. Planar Inverted “F” Antenna (PIFA) From: “FDTD Analysis of PIFA diversity antennas on a hand-held transreceiver unit” by Michael A. Jensen and Yahya Rahmat-Samii

  18. From: “Integrated Antennas for Hand-held Telephones with low Absorption’’ by Gert Frolund Rendersen, Jorgen Bach Andersen

  19. |Reflection Coefficient| = (Zo – ZL)/(Zo+ZL) Zo=50 ohms R=50 ohms? Resonant Frequency X PIFA ImpedanceZ = R + jX

  20. |S11| = |Reflection Coefficient Γ| (Less than half of the power is Reflected within this bandwidth) There will ALWAYS Be a higher harmonic Band. Must filter if unwanted. ½ Power Bandwidth

  21. CAPACITIVELY LOADED PIFAs • USUALLY LENGTH IS (L/4). • IT REDUCES IT TO (L/8). From: “A capacitively loaded PIFA for compact mobile telephone Handsets’’ by Corbett R. Powell, Student Member IEEE, and R.D. Murch, Member IEEE

  22. DUAL BAND PIFA 1

  23. TRIPLE BAND PIFA

  24. PIFA WITH MEANDER LINES

  25. DIVERSITY ANTENNAS(ie. MIMO)

  26. BPFA

  27. BPFA RADIATION PATTERN

  28. COMPARISON of DTSA and MONOPOLE SAR Distribution

  29. Loop Antenna From:http://www.downeastmicrowave.com/graphics/kbloop.gif

  30. Reflector (Dish) Antenna From: http://www.dssdirectv.com/chanmas1.jpg

  31. Arecibo Observatory -- Puerto Rico From: http://www.naic.edu/about/photos/aoviews/tescop.jpg

  32. Arecibo Observatory From:http://www.naic.edu/about/photos/aoviews/wideao.jpg

  33. GPS Antennas From:http://www.lowe.co.uk/gpsant.jpg

  34. Horn Antennas From: http://www.tmo.hp.com/tmo/datasheets/Images/img-HP11966J-1lg.gif From: http://www.afcsat.com/CH14_MOT2.jpg

  35. Antenna Arrays Two Elements -- Pattern adds constructively or destructively Array interaction is necsessary. From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat1.gif

  36. Antenna Arrays More Elements: Higher Directivity Sidelobes From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat2.gif

  37. Scanning Antenna Array Changing the phases on the element feeds can make a scanning array. From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat3.gif

  38. Arrays From:http://www.qth.com/antenna/tiny2rl.gif From: http://cust.iamerica.net/dwhowell/yagimax.jpg

  39. Polarization E E E

  40. HAARP Observatory HAARP (High frequency Active Auroral Research Program) is to be a major Arctic facility for upper atmospheric and solar-terrestrial research. HAARP is being built on a DoD-owned site near Gakona, Alaska. From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ohd.jpg

  41. HAARP Antenna ArrayCrossed Dipoles The HF antenna system to be used for Active Ionospheric Research at the HAARP site will assist other facility instruments in the study the overhead ionosphere. As a result, it too has been designed to optimize or restrict the transmission pattern to lie within a narrow overhead region. To achieve this desirable antenna pattern, the HAARP system uses an "array" of individual antenna elements. The HAARP antenna array is similar or identical to many other types of directive antenna types in use for both military and civilian applications including air traffic control radar systems, long range surveillance systems, steerable communication systems and navigation systems. From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/twr/pan2.jpg

  42. HAARP -- Feed Sytem From:http://server5550.itd.nrl.navy.mil/projects/ HAARP/images/ant/tpile.jpg

  43. HAARP -- Matching Networks From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/amu.jpg

  44. Corner Reflector Antenna Reflector acts like A “mirror” and produces Virtual antennas. From: http://www.northcountryradio.com/crfigs.htm

  45. Anything Radiates …Fan-tenna From:http://www.qth.com/antenna/fanfull.gif

  46. So .. Where do we go from here with MIMO? • Define Specifications (easier said than done) • Maximum size • Frequency and bandwidth • What does the “output” of the antenna set need to be to achieve optimal communication? • What antenna parameters affect that? • What antenna is optimal? • Parametric Studies • GA or direct optimization

  47. Antenna References on the Web General: http://www.ee.surrey.ac.uk/Personal/D.Jefferies/antennas.html GPS Antennas Lowe Industries :http://www.lowe.co.uk/antrev2.htmlhttp://www.lowe.co.uk/antrev2.html Antenna Calibration: http://gracie.grdl.noaa.gov/GRD/GPS/Projects/ANTCAL/index.shtml Ham: North Country Radio: http://www.northcountryradio.com/techtips.htm Antenna Elmer: http://www.qth.com/antenna/antenna.htm HAARP Observatory: http://server5550.itd.nrl.navy.mil/projects/HAARP/ant3.html Arecibo Obervatory: http://www.naic.edu/aboutao.htm

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