Theory Antenna Cppaste | Antenna (Radio)

Please download to get full document.

View again

of 312
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Information Report
Category:

Documents

Published:

Views: 10 | Pages: 312

Extension: DOCX | Download: 0

Share
Related documents
Description
teoria de antenas
Transcript
  http://www.antenna-theory.com/spanish/antena.php Introduction to  Antennas In the 1890s, there were only a few antennas in the world. These rudimentary devices were primarly a part of eperiments that demonstrated the transmission of electroma!netic waves. y #orld #ar II, antennas had $ecome so u$i%uitous that their use had transformed the lives of the avera!e person via radio and television reception. The num$er of antennas in the &nited 'tates was on the order of one per household, representin! !rowth rivalin! the auto industry durin!the same period. y the early (1st century, than)s in lar!e part to mo$ile phones, the avera!e  person now carries one or more antennas on them wherever they !o *cell phones can have multiple antennas, if +' is used, for instance. This si!nificant rate of !rowth is not li)ely to slow, as wireless communication systems $ecome a lar!er  part of everyday life. In addition, the stron! !rowth in I devices su!!ests that the num$er of antennas in use may increase to one antenna per o$ect in the world *product, container, pet, $anana, toy, cd, etc.. This num$er would dwarf the num$er of antennas in use today. 2ence, learnin! a little *or a lar!e amount a$out of antennas couldn3t hurt, and will contri$ute to one3s overall understandin!of the modern world.  4 50-meter dish antenna. art of 64'43s 7et ropulsion a$oratory *7 communication system.  Antenna Theory History #hat is the ori!in of the antenna I3m rulin! out such early devices as compasses, $ecause while they in some sense receive a ma!netic field, it is not an electroma!netic field. en ran)lin3s )ite eperiment wasn3t %uite an antenna, as that captured li!htnin! dischar!e, which is a direct current path where the ener!y is not transferred independent of the medium it travels. The human eye of course receives hi!h fre%uency electroma!netic waves *li!ht, to the layman.  Technically the eye could $e classified as an antenna however since it can3t transmit waves, it is really a sensor, so I3ll eclude that as well. The first eperiments that involved the couplin! of electricity and ma!netism andshowed a definitive relationship was that done $y araday somewhere around the18;0s. 2e slid a ma!netic around the coils of a wire attached to a !alvanometer. In movin! the ma!net, he was in effect creatin! a time-varyin! ma!netic field, which as a result *from <awell3s =%uations, must have had a time-varyin! electric field. The coil acted as a loop antenna and received the electroma!netic radiation, which was received *detected $y the !alvanometer - the wor) of an antenna. Interestin!ly, the concept of electroma!netic waves had not even $een thou!ht up at this point. 4 paintin! of <ichael araday. ein! a !reat eperimentalist, he naturallyda$$led in chemistry, shown here.2einrich 2ert> developed a wireless communication system in which he forced an electrical spar) to occur in the !ap of a dipole antenna. 2e used a loop antennaas a receiver, and o$served a similar distur$ance. This was 188?. y 1901, <arconi was sendin! information across the atlantic. or a transmit antenna, he used several vertical wires attached to the !round. 4cross the 4tlantic @cean, the receive antenna was a (00 meter wire held up $y a )ite A1B.  In 190?, Colum$ia &niversity had an =perimental #ireless 'tation where they used a transmittin! aerial ca!e. This was a ca!e made up of wires and suspended in the air, resem$lin! a ca!e A(B. 4 rou!h outline of some maor antennas and their discovery/fa$rication dates are listed:   Da!i-&da 4ntenna, 19(0s   2orn antennas, 19;9. Interestin!, the early antenna literature discussed wave!uides as Ehollow metal pipesE.  4ntenna 4rrays, 19F0s   ara$olic eflectors, late 19F0s, early 19G0s 7ust a !uess.   atch 4ntennas, 1950s.    I4, 1980s.Current research on antennas involves metamaterials *materials that have en!ineered dielectric and ma!netic constants, that can $e simultaneously ne!ative, allowin! for interestin! properties li)e a ne!ative inde of refraction. @ther research focuses on ma)in! antennas smaller, particularly in communications for personal wireless communication devices *e.!. cell phones. 4 lot of wor) is $ein! performed on numerical modelin! of antennas, so that their properties can $e predicted $efore they are $uilt and tested. eferencesA1B alanis, Constantine. E4ntenna Theory: 4 eviewE, roceedin!s of the I===,vol. 80, 7anuary 199(.A(B #(4== 4ntenna 2istory. 4rthur <. Hay *, scanned $y 4lan Crosswell. http://www.w(aee.colum$ia.edu/history/antenna-history.html  Antenna Basics Antenna Fundamentals ets !et ri!ht down to the study of antennas and Antenna Basics . 'uppose one day you3re wal)in! down the street and a )ind $ut impatient person runs up and as)s you to desi!n an antenna for them. E'ureE, you %uic)ly reply, addin! Ewhat is the desired fre%uency, !ain, $andwidth, impedance, and polari>ationE
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks