Vertical Dipole Antenna INFO WANTED

Vertical Dipole Antenna INFO WANTED

Post by Bill Hans » Tue, 24 Feb 2004 08:18:48

I am looking for a good source of information on Vertical Dipole
Antennas and their construction.  I you know of a good book or web
site, please email me.

Thanks,
Bill
= = = = = = =

Check our NEW EUROPEAN GLAMOUR photos

Click on this link: http://RoyaltyFreePhotos.com
Then do a search for: GLAMOUR
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Vertical Dipole Antenna INFO WANTED

Post by Activesignals.c » Tue, 24 Feb 2004 10:16:01




Quote:> I am looking for a good source of information on Vertical Dipole
> Antennas and their construction.  I you know of a good book or web
> site, please email me.

> Thanks,
> Bill
> = = = = = = =

> Check our NEW EUROPEAN GLAMOUR photos

> Click on this link: http://RoyaltyFreePhotos.com
> Then do a search for: GLAMOUR
> **************************************
> **************************************

here is a site for you

http://www.n2aqs.com/facts.html
--
**********************************************
*      Check out www.activesignals.com       *
*   It has LIVE CHAT and a forum board for   *
*   shortwave, amateur, and scanner radios   *
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Vertical Dipole Antenna INFO WANTED

Post by Fran » Tue, 24 Feb 2004 20:23:46

That's absurd.

Frank

 
 
 

Vertical Dipole Antenna INFO WANTED

Post by Fran » Tue, 24 Feb 2004 20:42:42


^ I am looking for a good source of information on Vertical Dipole
^ Antennas and their construction.

Sorry but I can't point you to a source but I can give you details here. The
construction of a receive-only dipole is very simple. All you need is some
coax of practically any type and two pieces of wire, also of almost any type.
Separate and expose the two conductors of the coax and attach one piece of
wire to each conductor. Cut each wire to the same length, the length
calculated for a frequency near the center of the listening area and as per
the following formula:

  LENGTH IN METERS = 75 / MEGAHERTZ

For example, if I'm listening to VHF civil aircraft frequencies, roughly
118MHz to 136MHz, I'll cut the wires for roughly 120MHz with the formula:

  75/120 = 0.625 meters

The orientation of the feedline, the coax, is not important. Just tape the
wire that is attached to the shielding back along the coax and leave the
other wire coming straight out. You can tape the whole thing to a wood,
plastic, fiberglass, or other non-conductive stick for stiffness.

Since this is a receive-only radio group these instructions are for a
receive-only antenna. The antenna does not need to be matched to a
transmitter so a matching transformer is not necessary.

Frank

 
 
 

Vertical Dipole Antenna INFO WANTED

Post by Tom Sevar » Wed, 25 Feb 2004 03:44:02


Quote:> I am looking for a good source of information on Vertical Dipole
> Antennas and their construction.  I you know of a good book or web
> site, please email me.

They're pretty simple & easy to build.  Here's one I built for 10 meters:

http://www.geocities.com/n2uhc_2/10m_dipole.html

--
Tom Sevart N2UHC
Frontenac, KS
http://www.geocities.com/n2uhc

 
 
 

Vertical Dipole Antenna INFO WANTED

Post by Tom Sevar » Wed, 25 Feb 2004 03:51:56


Quote:

>   LENGTH IN METERS = 75 / MEGAHERTZ

> For example, if I'm listening to VHF civil aircraft frequencies, roughly
> 118MHz to 136MHz, I'll cut the wires for roughly 120MHz with the formula:

>   75/120 = 0.625 meters

Or, to put that in American, L in feet = 468/MHz.

468/120 = 3.9 feet.  This is, of course, the length of the entire dipole.
For each leg, you'd use 234/120 = 1.95 feet, or simply divide the 3.9 by 2.

To convert the tenths of feet into inches, multiply by 12.  .9 X 12 = 10.8
inches.

--
Tom Sevart N2UHC
Frontenac, KS
http://www.geocities.com/n2uhc

 
 
 

Vertical Dipole Antenna INFO WANTED

Post by Fran » Wed, 25 Feb 2004 09:40:37



^ >
^ >   75/120 = 0.625 meters
^
^ Or, to put that in American, L in feet = 468/MHz.

I did use Amurican. Amurica is part of the international community and the
meter is the international standard measurement of length. Besides, it's much
easier to measure 0.625 meters on a bilingual yardstick, or meter stick, then
it is to measure 2.05 feet. It's also easier then doing the additional math
that you suggest.

^ 468/120 = 3.9 feet.  This is, of course, the length of the entire dipole.
^ For each leg, you'd use 234/120 = 1.95 feet, or simply divide the 3.9 by 2.

Note that the formula I gave produces the length of each leg. The
relationship is that electromagnetic energy travels at three hundred million
meters per second (300,000,000 m/s) and a megahertz is one million cycles per
second (1,000,000 1/s). To find meters (the length of one cycle) divide
3,000,000 by the frequency in MHz:

  300,000,000 m/s
-------------------
  120,000,000 1/s

The seconds divide out and 'm/1' becomes just 'm', and the resulting value is
the length of one wave in meters. Note that the 000,000 also divides out so
the math can be abbreviated as 300/120. To find a half or quarter wavelength
it is generally easier to first divide the 300 by two (150) or four (75),
which are easily remembered, then it is to perform the second division on the
resulting value.

To be more precise the resulting value for a quarter wavelength would be
multiplied by the velocity factor of the wire being used, but since these
antennas are normally intended for receiving a wide frequency range such
precision is generally wasted effort.

Frank

 
 
 

Vertical Dipole Antenna INFO WANTED

Post by Tom Sevar » Wed, 25 Feb 2004 14:36:20


Quote:> Besides, it's much
> easier to measure 0.625 meters on a bilingual yardstick, or meter stick,
then
> it is to measure 2.05 feet. It's also easier then doing the additional
math
> that you suggest.

Yes, but I don't have a tape measure that reads in meters.

Tom

 
 
 

Vertical Dipole Antenna INFO WANTED

Post by Volker Ton » Thu, 26 Feb 2004 02:39:52

Tom Sevart schrieb:

Quote:

> Yes, but I don't have a tape measure that reads in meters.

Poor boy. Or only just lazy?
Just make some additinal markings on a measuring stick you have...
....or do some maths. 1 inch is 2.54cm.

odo

PS: This was not meant rude in any way. Maybe somewhat sarcastic anyway:-)

 
 
 

Vertical Dipole Antenna INFO WANTED

Post by Tom Sevar » Thu, 26 Feb 2004 17:42:18


Quote:

> Tom Sevart schrieb:

> > Yes, but I don't have a tape measure that reads in meters.

> Poor boy. Or only just lazy?
> Just make some additinal markings on a measuring stick you have...
> ....or do some maths. 1 inch is 2.54cm.

They tried that here in the early 1980's, didn't work.  We're too used to
feet, inches, & miles.  No use for centimeters, hetimeters or kilometers.

Tom