[Antennas] CUSHCRAFT ANTENNAS

Sat, 9 Mar 2002 15:59:31 -0000

Subject: Re: [Antennas] CUSHCRAFT ANTENNAS
> At 03:43 PM 3/8/2002 +0000, you wrote:
> >
> >
> >Subject: Re: [Antennas] CUSHCRAFT ANTENNAS
> >
> >
> >> Why does a half wave antenna become less efficient by turning it on end
> >> (vertical ve horizontal half wave)
> >> -bob
> >
> >It doesn't...
>> Well, if you are interested, the folks at Butternut have a long, well
> documented and learned engineering report that in minute detail answers
the
> question put above.

 Butternut are a commercial organisation, who make a pretty good
product...I have a homebrew HF2 vertical myself..
> In a nutshell from my perspective the answer is
> simple:

When it comes to antennae, the answers are RARELY simple...!
> The "no radials" half wave vertical is not a half wave on most
> bands

Any half wave vertical can only be a half wave on ONE frequency (band)...
If you're referring to the R5/R7 Cushcraft, then it's a multiple 1/2 w/l
trapped dipole...except it's not centre fed. In fact a better analogy is
that of a trapped Windom antenna, stood on one end....The 49ins radials
equating to the short end of the Windom. It uses (pretty much) the same feed
system as well..i.e a 4:1 voltage balun fed by a 1:1 current (choke) balun.
(In the case of the Carolina Windom, the choke balun is mounted some
distance down the feeder.)
>and is not generally placed 1/2 wave above a good ground on the
> subject band in most cases.

An assumption...but probably true.(in my experience)
 > Anyhow, write Butternut and ask for the
> report.

 It's in my library for quite a while..
>Many people choose to believe that the "no radials" verticals are
> great antennas.

And some people believe that nominally 1/4 Lamda base loaded verticals over
a mediocre lossy ground systems are "the business"....AND THEY ARE....If
that's the only option they have...!!!
> That is your option if you choose it BUT the laws of
> physics are not subject to interpretation. Compared to a real antenna
> these are low in efficiency.

What's a " Real antenna"????
Efficiency is the ratio of the radiation resistance of an antenna, to it's
feedpoint impedance..no more...no less.
In the real World, Effectiveness, is as important as efficiency...e.g. A
typical HF mobile whip...efficient?? definately not..Effective?? yes.
> And I might add very expensive.

Only if you use the commercial variety....ALL my antennae are homebrew, and
cost little or nothing.
As it happens, I have a variety of verticals...one vertical dipole for 160m,
a pair of phased vertical dipoles on 80m, a 40m horizontal dipole, an HF2
ground mounted vertical (1/4 Lamda on 80/40m),
and a homebrew copy of the Cushcraft R7 (40 thru' 10m) mounted 20ft over
ground.
On 40m I can compare the horizontal dipole with the Butternut and Cushcraft
copies...
The comparisons are fairly predictable...
 On the close in stuff..UK and EU, the horizontal beats out both
verticals...
On DX, both verticals are equal on TX generally speaking. The R7 is
usually quieter on RX than the HF2.
in other words they are both very effective on 40m. However, the R7 is
easier to deploy, as a ground system is not mandatory, whereas with the HF2,
it definitely is...
 My ground mat consists of 40 x 60ft radials 10 x 30ft radials, and 8 x
130ft radials....Not perfect, but reasonably adequate.
 If I had to get rid of either the HF2 or the R7, I would get rid if the
HF2... because the R7 gives me all the other HF bands as well as 40m, and it
takes up the least space of any other antenna that I have.
Obviously, I don't give valuable space to antennae that DON'T WORK....! The
fact that I have them means that they are EFFECTIVE...Whether they're
EFFICIENT or not....??? 'Tell you what..I DON'T CARE....!!!
73
 John EI7BA
>> Bill k6erq
> >
> >>
> >> GoJolly wrote:
> >>
> >> > I have been casually reading all the posts about the Cushcraft
Verticals
> >> > with amusement.
> >> >
> >> > First thing is a "half wave vertical" with no radials is about the
same
> >as
> >> > putting a 100W lightbulb on the end of you coax and putting it on a
> >fence
> >> > post. The laws of physics are not subject to interpretation. The
> >> > efficiency is about 15%. So, if you are satisfied with 15W out, then
of
> >> > course the verticals work great. Lot of money to pay for that. ANY
> >kind
> >> > of wire antenna would be better with a little tweaking. And with the
> >poor
> >> > customer support that is reported...
> >> >
> >> > Seems like it's time to re-think using these products :-)
> >> >
> >> > My 2 cents worth.
> >> >
> >> > Bill K6ERQ
> >> > - - -
> >> >
> >> > Your moderator for this list is:
> >> > Larry Wilson KE1HZ [email protected]
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> >> >
> >> >
> >> >
> >>
> >>
> >> - - -
> >>
> >> Your moderator for this list is:
> >> Larry Wilson KE1HZ [email protected]
> >> _______________________________________________
> >> Antennas mailing list
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> >> http://mailman.qth.net/mailman/listinfo/antennas
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> >>
> >
>>