Twinlead antenna
 

I needed an indoor HF antenna recently and had a 40 ft roll of Radio
Shack twinlead. I cut down the middle about 16.5 feet, hung one end at
one side of the room and the other end at the other side of the room and
fed it into the balanced line input on my tuner. It tunes easily. I
have no ground set up, so I ran another 16.5 foot wire from the ground
port. Making contacts is a bit of a struggle, from my QTH in Michigan
I've worked Nevada and Arizona on PSK and during the DX contest today in
limited operation near sunset I worked Barbados and the Dominican
Republic with about 50W (probably a bit of a high level of RF radiation,
I know). The question I have is what the downside of this is. I have
seen many websites that show various antennas fed with twinlead, but
I've never seen my approach (the twinlead used for both the antenna and
feedline). Since I got this roll of twinlead on clearance from Radio
Shack for 38 cents, this is a cheap antenna indeed.

73,
Paul, N8HM

Twinlead antenna
 

"Paul R. Stoetzer" wrote in message
...
I needed an indoor HF antenna recently and had a 40 ft roll of Radio Shack
twinlead. I cut down the middle about 16.5 feet, hung one end at one side
of the room and the other end at the other side of the room and fed it into
the balanced line input on my tuner. It tunes easily. I have no ground set
up, so I ran another 16.5 foot wire from the ground port. Making contacts
is a bit of a struggle, from my QTH in Michigan I've worked Nevada and
Arizona on PSK and during the DX contest today in limited operation near
sunset I worked Barbados and the Dominican Republic with about 50W
(probably a bit of a high level of RF radiation, I know). The question I
have is what the downside of this is. I have seen many websites that show
various antennas fed with twinlead, but I've never seen my approach (the
twinlead used for both the antenna and feedline). Since I got this roll of
twinlead on clearance from Radio Shack for 38 cents, this is a cheap
antenna indeed.

73,
Paul, N8HM
Paul,
Should work fine on the higher frequencies. But it may have limited utility
on 160, 80, and 40
since it is only about 10 meters long. I assume your contacts were on 20
meters. where your
balanced line might be near 72 ohms.

If it is truly balanced you should not need a ground. Assuming
that the high RF in your room does not bother your rig/setup and assuming
that no one gets burned
by coming in contact with the antenna while you are operating, you should be
ok.

Ed, N5EI

Twinlead antenna
 

Paul R. Stoetzer wrote:
I have
seen many websites that show various antennas fed with twinlead, but
I've never seen my approach (the twinlead used for both the antenna and
feedline).

Balanis illustrates exactly that idea on page 18 of
"Antenna Theory, Analysis and Design", 2nd edition.
It is a very old idea. 50+ years ago, when I was a
Novice, it was standard practice to tie a knot in zip
cord 1/4WL from the end, unzip the cord down to the
knot, use the unzipped part for the 1/2WL antenna,
and use the rest for balanced feedline. It worked
like a charm in spite of the feedline losses.
--
73, Cecil http://www.qsl.net/w5dxp