Original article from: Wayne Sarosi 
 Reposted by Rob Dennis,Moderator HAM_TECH,for use of the FIDO HAM_TECH echo.
  THIS POST/SERIES NOT TO BE USED IN ANY CDROM COMPILATIONS FOR COMMERCIAL
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SUBJECT:  Wire antennaas - part 2
 In this posting,we'll look at long wires and random wire misconceptions.
 Placing an undertermined length of wire out to a tree or supporting mast is
*not* a long wire antenna.
 This is a random wire antenna which most of the amateur community calls a
`longwire' antenna. This misconception leads to many discouraging ideas about
longwires. A long wire antenna is an antenna that is at least 5 wave lengths
at the lowest frequency. After 5 wave lengths,the SWR becomes insignificant 
o
the xcvr for a properly tuned long wire.
 Five wave lengths you say. Yes,- 5 - wave lengths.
 So,at 3.75 MHz the length of a minimum long wire would be:
 (984/fMHz) X 5 or 1312-ft.
 Not an antenna you can slap in most backyards unless you are a rancher.
 When it comes to VHF and above,the longwire antenna can be easily outclassed
by numerous other designs,but at low HF frequencies the other designs become
too cumbersome to use and the longwire fills the niche.
 Let's take a look at the random wire antenna used by so many of us hams.
 A tuner is a must for any work with a random wire antenna.
 These antennas usually consist for a wire stretched between here and there.
 Dissapointed hams soon find that the easy way out isn't the answer.
 That 75-ft wire is not going to get them the performance they invisioned.
 Random wires are good for SWLing provided a tuner is used with the antenna.
 They're cheap to construct and cheap to buy. But a 75-ft wire in a standard
size lot is not much of an antenna for amateur radio use.
 Granted,it maybe all you can afford or be able to set-up at your QTH,but a
ham can do better for transceiving.
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 Longwires can provide nearly 3dB of gain over a dipole at 4 wave lengths
provided the antenna is sufficiently placed above the ground and the wave
angle of the antenna is correct.
 Five wave lengths is minimal for best results.
 The formula for longwire length is:
  Length in ft= 984(N-0.0250)/fMHz where N is the number of wavelengths.
 The longwire is a fixed antenna,so care should be taken where the antenna is
to be placed.
 Your favorite RF stomping grounds such as Europe or the Far East,etc should
be kept in mind.
 Next posting will have some additional information on longwires and other
wire antennas for standard size lots.
-WS
--- GoldED 2.42.G1219
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