Pertemuan 5 - 7  PANDU GELOMBANG Umiatin, M.Si Jurusan Fisika Fakultas Matematika dan Ilmu Pengetahuan Alam
<ul><li>Pandu gelombang : </li></ul><ul><li>modus TE, TM, dan TEM pada pandu gelombang berbentuk persegi </li></ul><ul><li...
CAHAYA,  light <ul><li>Aliran partikel yang dalam pemancarannya memenuhi hukum optik    reflection & refraction,  snell l...
Rambatan Cahaya Gelombang merambat secara spheric If didekat sumber Gelombang merambat secara planar If relatif jauh dari ...
Matematika Gelombang <ul><li>Cahaya dapat dianggap gelombang  yang mempunyai polarisasi linear ataupun elliptik. Polarisas...
Rambatan GEM Polarisasi bisa linear ataupun elliptical / circular tergantung nilai medan E dan H. 02/02/11 ©  2010 Univers...
Polarisasi <ul><li>Dengan asumsi bahwa cahaya merupakan gelombang EM, maka ada phenomena “POLARISASI” </li></ul><ul><li>LI...
Mode  <ul><li>Pattern atau bentuk pola rambatan sinyal EM atau cahaya terhadap penampang lintang saluran transmisi. </li><...
Penampang WG 02/02/11 ©  2010 Universitas Negeri Jakarta  |  www.unj.ac.id  |
Modes <ul><li>Waves can propagate in various ways </li></ul><ul><li>Time taken to move down the guide varies with the mode...
Propagasi Multimode 02/02/11 ©  2010 Universitas Negeri Jakarta  |  www.unj.ac.id  |
Mode Designations <ul><li>TE: transverse electric </li></ul><ul><ul><li>Electric field is at right angles to direction of ...
Rectangular Waveguides <ul><li>Dominant mode is TE 10 </li></ul><ul><ul><li>1 half cycle along long dimension (a) </li></u...
Mode TE transverse electric (TE) mode:  A  mode  whose  electric field  vector is normal to the direction of  propagation ...
Cutoff Frequency <ul><li>cutoff mode: The highest order  mode  that will propagate in a given  waveguide  at a given  freq...
Cutt0ff wavelength cutoff wavelength: 1.  The  wavelength  corresponding to the  cutoff frequency . ( 188 )  2.  In an unc...
Usable Frequency Range <ul><li>Single mode propagation is highly desirable to reduce dispersion  </li></ul><ul><li>This oc...
Mode TM transverse magnetic (TM) mode:  A  mode  whose magnetic  field  vector is normal to the direction of  propagation ...
Mode TEM transverse electric and magnetic (TEM) mode:  A  mode  whose electric and magnetic  field  vectors are both norma...
Example Waveguide <ul><li>RG-52/U </li></ul><ul><li>Internal dimensions 22.9 by 10.2 mm </li></ul><ul><li>Cutoff at 6.56 G...
TERIMA KASIH 02/02/11 ©  2010 Universitas Negeri Jakarta  |  www.unj.ac.id  |
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Teori Medan Elektromagnet (5 - 7) pandu_gelombang

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Teori Medan Elektromagnet (5 - 7) pandu_gelombang

  1. 1. Pertemuan 5 - 7 PANDU GELOMBANG Umiatin, M.Si Jurusan Fisika Fakultas Matematika dan Ilmu Pengetahuan Alam
  2. 2. <ul><li>Pandu gelombang : </li></ul><ul><li>modus TE, TM, dan TEM pada pandu gelombang berbentuk persegi </li></ul><ul><li>modus TE, TM, dan TEM pada pandu gelombang berbentuk silinder </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  3. 3. CAHAYA, light <ul><li>Aliran partikel yang dalam pemancarannya memenuhi hukum optik  reflection & refraction, snell law . </li></ul><ul><li>Radiasi gelombang elektromagnetik (fresnel, maxwell) dengan diffraction, interference dan pengubahan polarisasi selain mengalami reflection & refraction. </li></ul><ul><li>Pendekatan “ray” yang juga dapat mengalami diffraction, interference dan pengubahan polarisasi selain mengalami reflection & refraction. </li></ul><ul><li>Arah rambat cahaya dari sumbernya dapat diasumsikan gelombang spheric ataupun plane </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  4. 4. Rambatan Cahaya Gelombang merambat secara spheric If didekat sumber Gelombang merambat secara planar If relatif jauh dari sumber 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  5. 5. Matematika Gelombang <ul><li>Cahaya dapat dianggap gelombang yang mempunyai polarisasi linear ataupun elliptik. Polarisasi tergantung pada kondisi vektor medan E dan H. </li></ul><ul><li>Sebagaimana gelombang EM, cahaya mempunyai konstanta propagasi, dengan notasi k. </li></ul><ul><li>Agar merambat, medan E dan H membentuk vektor yang orthogonal agar terjadi transverse wave. </li></ul><ul><li>Mode perambatan cahaya di serat optik, secara umum mengikuti hukum perambatan gelombang EM yang diturunkan oleh MAXWELL. </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  6. 6. Rambatan GEM Polarisasi bisa linear ataupun elliptical / circular tergantung nilai medan E dan H. 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  7. 7. Polarisasi <ul><li>Dengan asumsi bahwa cahaya merupakan gelombang EM, maka ada phenomena “POLARISASI” </li></ul><ul><li>LINEAR (Vertical - Horizontal) </li></ul><ul><li>ELLIPTICAL (circular, RHCP, LHCP) </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  8. 8. Mode <ul><li>Pattern atau bentuk pola rambatan sinyal EM atau cahaya terhadap penampang lintang saluran transmisi. </li></ul><ul><li>Contoh : </li></ul><ul><li>Mode TE dan TM terjadi pada saluran transmisi dan WG </li></ul><ul><li>Mode TEM hanya terjadi di udara </li></ul><ul><li>Dalam fiber hitungan TE, merupakan pendekatan termudah </li></ul><ul><li>Monomode dan multimode merupakan istilah yang mengacu pada jumlah gelombang yang merambat dalam setiap “kanal”. </li></ul><ul><li>Laser Multimode adalah laser yang dapat mengirim banyak “lambda” dalam waktu yang sama. </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  9. 9. Penampang WG 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  10. 10. Modes <ul><li>Waves can propagate in various ways </li></ul><ul><li>Time taken to move down the guide varies with the mode </li></ul><ul><li>Each mode has a cutoff frequency below which it won’t propagate </li></ul><ul><li>Mode with lowest cutoff frequency is dominant mode </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  11. 11. Propagasi Multimode 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  12. 12. Mode Designations <ul><li>TE: transverse electric </li></ul><ul><ul><li>Electric field is at right angles to direction of travel </li></ul></ul><ul><li>TM: transverse magnetic </li></ul><ul><ul><li>Magnetic field is at right angles to direction of travel </li></ul></ul><ul><li>TEM: transverse electromagnetic </li></ul><ul><ul><li>Waves in free space are TEM </li></ul></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  13. 13. Rectangular Waveguides <ul><li>Dominant mode is TE 10 </li></ul><ul><ul><li>1 half cycle along long dimension (a) </li></ul></ul><ul><ul><li>No half cycles along short dimension (b) </li></ul></ul><ul><ul><li>Cutoff for a =  c/2 </li></ul></ul><ul><li>Modes with next higher cutoff frequency are TE 01 and TE 20 </li></ul><ul><ul><li>Both have cutoff frequency twice that for TE 10 </li></ul></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  14. 14. Mode TE transverse electric (TE) mode: A mode whose electric field vector is normal to the direction of propagation . Note: TE modes may be useful modes in waveguides. In an optical fiber , TE and TM modes correspond to meridional rays . meridional ray: In fiber optics , a ray that passes through the optical axis of an optical fiber (in contrast with a skew ray , which does not). 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  15. 15. Cutoff Frequency <ul><li>cutoff mode: The highest order mode that will propagate in a given waveguide at a given frequency . </li></ul><ul><li>For TE 10 mode in rectangular waveguide with a = 2 b </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  16. 16. Cutt0ff wavelength cutoff wavelength: 1. The wavelength corresponding to the cutoff frequency . ( 188 ) 2. In an uncabled single-mode optical fiber , the wavelength greater than which a particular waveguide mode ceases to be a bound mode . ( 188 ) Note 1: The cutoff wavelength is usually taken to be the wavelength at which the normalized frequency is equal to 2.405. Note 2 : The cabled cutoff wavelength is usually considered to be a more functional parameter because it takes into consideration the effects of cabling the fiber. 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  17. 17. Usable Frequency Range <ul><li>Single mode propagation is highly desirable to reduce dispersion </li></ul><ul><li>This occurs between cutoff frequency for TE 10 mode and twice that frequency </li></ul><ul><li>It’s not good to use guide at the extremes of this range </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  18. 18. Mode TM transverse magnetic (TM) mode: A mode whose magnetic field vector is normal to the direction of propagation . Note: TM modes may be useful in waveguides. In an optical fiber , TE and TM modes correspond to meridional rays . 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  19. 19. Mode TEM transverse electric and magnetic (TEM) mode: A mode whose electric and magnetic field vectors are both normal to the direction of propagation . Note: The TEM mode is the most useful mode in a coaxial cable or Radio propagation. 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  20. 20. Example Waveguide <ul><li>RG-52/U </li></ul><ul><li>Internal dimensions 22.9 by 10.2 mm </li></ul><ul><li>Cutoff at 6.56 GHz </li></ul><ul><li>Use from 8.2-12.5 GHz </li></ul>02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |
  21. 21. TERIMA KASIH 02/02/11 © 2010 Universitas Negeri Jakarta | www.unj.ac.id |

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