TAK-TENNA
patrick.obrien47
Has anyone bought this small TAK-tenna HF Aerial
? or know anyone that has?
Just wonder how they got on with it.?
Patrick GW1SXN
Frank
"patrick.obrien47" <patrick....@virgin.net> wrote in message
news:xg7Qj.34259$B83....@newsfe3-gui.ntli.net...
Just for curiosity I once ran a NEC simulation of the "TAK-tenna" on 7 MHz
at 30 ft
above an average ground. The input impedance at resonance is 3.4 ohms, and
radiation efficiency just under 9%. Using 50 ft of RG-213 the input
impedance
is 5.4 + j 12.4 ohms, and line loss 1.72 dB. Maximum gain, at a 30 degree
take-off
angle, shows -7.7 dbi. Nulls off each end are -14 dbi.
With the above results an input power of 100 W radiates 6 W. I believe they
claim
a low input VSWR. Have no idea how they achieve it without a matching
network.
73,
Frank
(VE6CB)
Frank
> Just for curiosity I once ran a NEC simulation of the "TAK-tenna" on 7 MHz
> at 30 ft
> above an average ground. The input impedance at resonance is 3.4 ohms,
> and
> radiation efficiency just under 9%. Using 50 ft of RG-213 the input
> impedance
> is 5.4 + j 12.4 ohms, and line loss 1.72 dB. Maximum gain, at a 30 degree
> take-off
> angle, shows -7.7 dbi. Nulls off each end are -14 dbi.
>
> With the above results an input power of 100 W radiates 6 W. I believe
> they claim
> a low input VSWR. Have no idea how they achieve it without a matching
> network.
Running more models, and accounting for the coaxial shield, indicates a
dramatic
improvement in radiation efficiency. Resonances are noted to have a much
better match under these conditions, and are highly dependant on coaxial
cable length and position. The NEC code below shows one version
with an indicated efficiency of 76% and a gain in the region of -1 dbi.
With a modified version of the code, including 29 ft of
vertical transmission line, the input impedance was observed to be
near 25 ohms, and resonant at 7.6 MHz. Probably playing around
with various combinations of antenna taps, transmission line length,
and position would achieve something better. Typically the program
takes 2 minutes to run, so optimizing is very tedious.
It appears that many of these ultra compact antenna designs
rely on radiation from the transmission line.
73,
Frank
CM Tek-Tenna
CE
GH 1 203 6.75 0 5 15 0.03205 0.03205 1
GM 0 0 90 90 0 0 0 0
GM 1 1 0 0 0 0 30 0
GM 100 0 0 0 0 0 0 360
GW 3 30 -6.0428 0 360.704 -6.0428 30 360.704 0.03205
GW 4 1 -300 14 1 -300 15 1 0.03205
GW 5 424 -6.0428 15 360.704 -300 14 1 0.03205
GS 0 0 0.025400
GE 1 -1 0
GN 2 0 0 0 13.0000 0.0050
FR 0 21 0 0 14 0.1
EX 0 4 1 0 1 0
TL 3 15 4 1 50.00 16.317575 ! RG-58C #20 Flex
LD 5 0 0 0 5.8001E7
RP 0 1 361 1000 60 0 1.00000 1.00000
EN
Ken Halliwell
>
> It appears that many of these ultra compact antenna designs
> rely on radiation from the transmission line.
>
Thus, the reason folks who attempt to use a balun, feedline choke or
balanced line appear to have performance problems with the Tak-tenna
-- according to eham.com reviews of the antenna.
Ken - WA8FCI
stufir...@gmail.com
Steer clear of the so called TAK-tenna site, you won't get your antenna. So, all in all, can't tell you how it works.
Helmut Wabnig
wrote:
I once ordered a direction finding antenna from USA for 100$
plus 50 $ postage plus 20$ customs, and all I got was some bent wire
with loose connectors. The coax cable was not even soldered or
crimped on the BNC central pin!
I am Austrian, the other guy is Australian, not far away :-)
Ceterum Censeo, USA must be punished.
w.
W5DXP
--
73, Cecil, w5dxp.com
Jeff Liebermann
-.dotat> wrote:
>>On Friday, April 25, 2008 7:50:21 AM UTC+10, patrick.obrien47 wrote:
>>> HI
>>> Has anyone bought this small TAK-tenna HF Aerial
>>> ? or know anyone that has?
moron who gets his jollies reposting old messages.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Ralph Mowery
"W5DXP" <w5...@hotmail.com> wrote in message
news:c4f377d1-35c3-4f96...@googlegroups.com...
of the past.
It is often cheaper just to buy something already made. Say I was going
to put up something like the G5RV. I have to buy some wire. The wire is
just over 100 feet. That might mean buying 500 feet on a roll or ordering
it with the postage. Then need some ladder line. Need about 35 feet. Have
to get either 50 or 100 feet if I can find it locally, probably not any
around now as most TV sets use cable or coax. Also insulators and coax to
locate. Things start to add up. Or I could get it all in one 'kit' for much
less.
Not all hams have a place to store supplies or build things that are large.
I sometimes build and sometimes buy. I just bought something to program
some radios off ebay. It was a circuit board with the parts on it. I did
have to put it in a box. The board only had 1 IC and a few capacitors and
leds on it. Two boards shipped was only $ 7.99. The shiping could have
more than that at some places. I was going to order a VHF preamp kit but
the postage put me off. They wanted $ 12.00 for postage. I could have put
50 of those kits in the $ 5.50 UPS mailing box. The kit was about the same
as the postage.
