[NSRCA-discussion] 2,4 Module

[Jay Marshall]

In free space.  Wire and dielectric will alter this somewhat. <grin>

 

Jay Marshall 

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Mark Atwood
Sent: Thursday, May 08, 2008 11:20 AM
To: General pattern discussion
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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