[Elecraft] Portable 60-80m wire antennas

[Scott Ellington]

I've always been a fan of end-fed half wave wires for portable 
operation, as they don't require a ground system, nor do they require a 
balun or feedline.  The inverted L configuration works well, as the high 
current point is a quarter wave from the fed end.  Make that as high as 
you can.  The horizontal part of the wire radiates much like a dipole.  
It will also work, perhaps not quite as effectively, simply sloping up 
from the feedpoint.  Note that this is antenna NOT the same as the usual 
quarter wave inverted L, which has maximum current at the feedpoint, and 
works more like a vertical.

The downside is that the feedpoint impedance is very high, perhaps 2,000 
Ohms, which may be beyond the range of the KX1 tuner.  It is, however, 
very easy to build an L network to match it.  (I can provide L and C 
values.)   I'd also attach a couple short wires to the radio ground to 
act as a counterpoise, though it may not make much difference.  A couple 
6 foot wires should work for 80 and above.

This kind of antenna will work on any band for which it is a multiple of 
a half wavelength, though the radiation pattern will be like a long wire 
at higher frequencies.  On 10 and 15 meters, if you can get a half 
wavelength wire nearly vertical, it will act like a half wave vertical, 
which may be better for low radiation angles.  I used one of those a few 
years ago in the 10 Meter contest from KP2 and, in spite of a terrible 
location, a bunch of people heard me.

73,

Scott  K9MA

>> On Mar 15, 2016, at 12:59 PM, Bruce Nourish <w0mbt at w0mbt.net> wrote:
>>
>> Hi folks,
>>
>> For 40m, 30m, and 20m, the KX1 docs recommend a ~24' length of
>> sorta-vertical #24 wire with shorter counterpoises as a good field antenna.
>> I've set that up for my KX1 and KX3, and (unsurprisingly) it works well on
>> both.
>>
>> For 80m, the KX1 docs recommend a resonant antenna, and I'm considering my
>> options. Most of what's written out there about low band antennas seems to
>> be about durable (and heavy) mobile or home installations. Does anyone have
>> any experience they'd like to share with backpackable lower band antennas?
>>
>> Options and questions I'm considering include:
>>
>> * Build a coil big enough to load up my 24' vertical on 80m, with a tap for
>> 60m. Will that be a long enough radiator?
>>
>> * Figure out the kite-vertical thing, fly a wire close enough to l/4 that
>> the KX1 can tune it. How bulky would that be?
>>
>> * Will #24 wire be a decent radiator for the lower bands, or should I eat
>> the (not-inconsiderable) weight of a bigger gauge?
>>
>> * Does anyone have any tips on constructing backpackable (minimum weight)
>> coils? What's the smallest wire and lightest insulator?
>>
>> * I'm planning a vertical, as this would seem to require strictly less wire
>> and coils than any dipole or inverted vee, but am I missing some other
>> offsetting advantage?
>>
>> Cheers,
>> Bruce
>> ______________________________________________________________
>>

-- 
Scott Ellington  K9MA
Madison, Wisconsin, USA

k9ma at sdellington.us