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====== π-box - How to build an antenna ======

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===== Material =====

{{ :documentation:400px-ANTENNA.jpeg|frame|none]]

∏-Box Antenna Ready to Broadcast   * One Coaxial T {{ :documentation:CoaxTbis.jpg?nolink |}}   * One Coaxial female adaptor {{ :documentation:CoaxFabis.jpg?nolink |}}

  * 2 Coaxial Telescopic Antennas {{ :documentation:CoaxAntbis.jpg?nolink |}}
  * Coaxial RG 174 wire {{ :documentation:Wirebis.jpg?nolink |}}
  * 1 GPIO Jumper (needs only 2 slots) {{ :documentation:JumperGPIO.jpg?nolink |}}

===== Other Needs =====

  * soldering station
  * tape

===== Tutorial =====

First, prepare the Wire, connect the wire to the coaxial female adaptator.

{{ :documentation:TTEr2.jpg?nolink |}}

{{ :documentation:TTEr5.jpg?nolink |}}

Connect the wire to the GPIO Jumper.

{{ :documentation:TTEr4.jpg?nolink |}}

Add some tape.

{{ :documentation:TTEr3.jpg?nolink |}}

The wire is ready, now let's make the antenna

open the coaxial T, take off the balloon, disconnect one output, break the cover of the side coaxial output.

{{ :documentation:OpenTBis.jpg?nolink |}}

cover it back with tape, open slightly the male plug so it can host one telescopic antenna then connect the wire.

{{ :documentation:GPIOs.png|frame|none]]

last, connect the Antenna to the Rasperri Pi on GPIO 4 (ports 7) & GROUND (ports 9)

{{ :documentation:Antennafinish.jpg?nolink |}}



{{ :documentation:AntennaRady.jpg?nolink |}}

Ready for transmission !
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===== Measure =====

{{ :documentation:800px-DipoleAlu.jpg?nolink |}}

Test transmission with pi-box + dipole antenna made with rigid aluminium tube

{{ :documentation:800px-Dipolecuivrecable.jpg?nolink |}}

Test transmission with pi-box + dipole antenna made with flexible copper cable

{{ :documentation:800px-SansAntenne.jpg?nolink |}}

Test transmission with pi-box without antenna

{{ :documentation:800px-Velo.jpg?nolink |}}

Test transmission with transmitter 5 watts (?) with an antenna fixed to a bike (a bike as antenna)

===== Theorical ressources =====

==== Understand and measure antennas ====

  * http://wiki.electrolab.fr/Projets:Lab:2015:Tuto_VNWA:Les_Antennes_introduction
  * http://wiki.electrolab.fr/Projets:Lab:2015:Tuto_VNWA:Les_Antennes

==== Technical ressources ====

  * Simple dipole antenna by Tetsuo Kogawa https://anarchy.translocal.jp/radio/micro/howtomakeantenna200708.pdf
  * Antenne dipole http://www.petoindominique.fr/php/antenne.php
  * Antennas types and calculs http://exam2ham.free.fr/donnees/antennes.html
  * How to calculate the lenght of a 1/4 wave or 1/2 wave antenne ? http://www.bmweb.fr/radio/mat_antennes.php
  * Basics of the antennas [[BAsicsOnAntennas-an-00500.pdf|BAsicsOnAntennas-an-00500.pdf]]
  * Build a low tech antenna with agricultural material https://www.instructables.com/id/Low-Power-FM-Transmitter-Antenna-From-Agricultural/ For example, to build a dipôle antenna for 108 MHz frequency, with 2 tubes of coper, the global lenght of the antenna will be 1389 mm, if we let 1 cm of space between the 2 tubes of coper, then each tube must mesure ~ 68,9 cm {{ :documentation:IMG_2919.redim.jpg?nolink |}}

==== Pre built antennas ====
  * [https://www.passion-radio.com/fr/antennes/antenne-ant500-74.html](https://www.passion-radio.com/fr/antennes/antenne-ant500-74.html](télescopic (hackrf antenna))
  * more expensive https://www.passion-radio.com/fr/fixe/super-discone-264.html
  * pro [http://radiotelevision.free.fr/index1.html http://radiotelevision.free.fr/index1.html http://www.broadcast-eletec.com/equipement-fm/antenne-demission-fm/]