[NSRCA-discussion] 2,4 Module

[Keith Black]

Re: [NSRCA-discussion] 2,4 ModuleThank goodness the 72Mhz setups can use 1/4 wave antennas. Sure would look funny to see a flight line of four meter long antennas! ;-)

Keith Black
  ----- Original Message ----- 
  From: Mark Atwood 
  To: General pattern discussion 
  Sent: Thursday, May 08, 2008 10:19 AM
  Subject: Re: [NSRCA-discussion] 2,4 Module


  The antenna's we used on the 72mhz band were 1/4 wave antenna's.  Approx 1 m.  The 72Mhz wavelength is 416cm for a full wave (varying some for which specific frequency you were on.

  The 2.4Ghz wavelength is only 12.4cm or about 4.8in.   So an equivalent quarter wave antenna will only be about 1.2in in length.

  -M

  PS for those that care, wavelength (in cm) = speed of light (in cm) / Frequency (in cycles per second)


  On 5/8/08 10:54 AM, "rcmaster199 at aol.com" <rcmaster199 at aol.com> wrote:


    ***When you realize all this from that measley little 4" antenna, it's almost jaw-dropping.  ***

     
    Basically, the length of the antenna is related to frequency of the transmission. 2.4 gig freq is made up of small wavelength. If you remember High School Physics, the relation between Freq and Wavelength... ie- it's an inverse relationship. As Freq goes up, WL becomes small. At 72 meg, WL is fairly long, hence the reason for the longer antenna; at 27 meg, wl is even longer. Those who used 27 meg equipment a bunch of moons ago, will remember that Tx and RX antennas were pretty long and only represented 1/2 the WL (I think it was 1/2)
     
    Dean Pappas, Ed Alt and Jim Oddino can explain further if needed
     
    BTW, tuning a pipe on a 2 stroke requires similar understanding between rpm (base frequency) and tuning length (wavelength of the exhaust pressure front and type of exhaust) to achieve the desired resonance....similar to electrical antennas. QED
     
    MattK
     
     



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