antenna length

 Posts: 3
 Joined: Tue Sep 17, 2002 1:01 am
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antenna length
what is the formula for figuring antenna length
Re: antenna length
c = 3x10^8 m/s (300,000,000 m/s)<p>1/4 wave whip antenna<p>length = c/(4*f) meters<p>example:<p>2.4 GHz  (3x10^8)/(4*(2.4x10^9)) = 3.125 cm<p>900 MHz  (3x10^8)/(4*(9x10^8)) = 8.333 cm<p>27 MHz  (3x10^8)/(4*(2.7x10^7)) = 2.778 m

 Posts: 3
 Joined: Tue Sep 17, 2002 1:01 am
 Contact:
Re: antenna length
I don't understand the math but maybe you can help.Can you give me the lengths on quarter wave
320 mgz
460 mgz
800 mgz
125 mgz
75 mgz
320 mgz
460 mgz
800 mgz
125 mgz
75 mgz
Re: antenna length
bobsRAC has just presented the standard formula in a slightly different way  try this<p>Radio Waves travel at 300,000,000 metres/second
If you have the frequency (f) and you want to know wavelength in metres(m) then you just divide 300,000,000 by the frequency eg:
wavelength = 300,000,000/320,000,000 (320MHz)
wavelength = 0.9375 metres or if you prefer 93.75cm hope not!
a 1/4 wavelength is 93.75/4 =23.44cm.<p>Conversely take your 0.9375m and divide your speed of light the 300,000,000 by 0.9375 and hey presto you have converted wavelength back into frequency.<p>Bobs example only looks strange because he used the short hand way of expressing numbers as 10 to the power of; and he included the divide by 4 in one go.<p>[ October 30, 2002: Message edited by: bodgy ]</p>
If you have the frequency (f) and you want to know wavelength in metres(m) then you just divide 300,000,000 by the frequency eg:
wavelength = 300,000,000/320,000,000 (320MHz)
wavelength = 0.9375 metres or if you prefer 93.75cm hope not!
a 1/4 wavelength is 93.75/4 =23.44cm.<p>Conversely take your 0.9375m and divide your speed of light the 300,000,000 by 0.9375 and hey presto you have converted wavelength back into frequency.<p>Bobs example only looks strange because he used the short hand way of expressing numbers as 10 to the power of; and he included the divide by 4 in one go.<p>[ October 30, 2002: Message edited by: bodgy ]</p>
On a clear disk you can seek forever.
Re: antenna length
Hello, Most antennas are dipoles and the formula
is as follows, I = 468 / frequency in MHZ
example 468 divided by 75 Megahertz is 6.24 feet
is the length overall. With a dipole, each side
would be 3.12 feet. hope this helps.
is as follows, I = 468 / frequency in MHZ
example 468 divided by 75 Megahertz is 6.24 feet
is the length overall. With a dipole, each side
would be 3.12 feet. hope this helps.
Re: antenna length
My brother had a 16 ga. bellwire dipole in the
eaves of the house. On L.I., he rcvd. Maryland
stations in clear stereo(5gang Realistic tuner).
But I'd be more interested in the equations for..
Reactance of a wire antenna based on its parallel distance from the gnd.plane, and..
How to determine coil dimentions on an extended
whip. ( Like Nextel's 5db gain trunk mount).
Whip out those calculus books !!!!!
eaves of the house. On L.I., he rcvd. Maryland
stations in clear stereo(5gang Realistic tuner).
But I'd be more interested in the equations for..
Reactance of a wire antenna based on its parallel distance from the gnd.plane, and..
How to determine coil dimentions on an extended
whip. ( Like Nextel's 5db gain trunk mount).
Whip out those calculus books !!!!!
Can't we end all posts with a comical quip?
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