In a message dated 9/2/01 9:51:58 AM Pacific Daylight Time, teamw@quixnet.net
writes:
<<
I agree with AA2MF regarding the need for more info on simple, unique or
creative antennas for hams with small lots. We need to realize that,
regardless of original intent, this is no longer a USA-only reflector but
due to the nature of the web is world wide in readership.
In addition to those in the US, there are countless thousands of hams, or
potential hams overseas in densely populated environments who cannot get on
the air due to space limitations, possibly allied with a lack of small
antenna know-how.
I have a horse laugh when contributors comment that they "only" have a 100ft
x 50ft lot and can "only" get up a 50 ft tower etc.
Try an industrial revolution era terraced house with front and rear yards
measuring 15 x 15 ft each. Probably heavily developed by the XYL with
concrete path, flower beds, a tiny pond and a microscopic lawn. I have a
retiree friend in Europe with such a situation and he is by no means unique.
I designed a squashed rectangular quad for 15 mtrs to fit into his attic
space which is 12 x 10 ft and 8 ft high. It works quite well but he would
sure like to get on 20m to work me occasionally. For some other bands he
uses a covert 22 awg invisible end fed wire going across the street but
without an RF ground system. This naturally has mediocre performance.
Another caveat is that many such residences, especially in Europe, are owned
by the city and rented to the tenants and therefore can be subject to what
are essentially deed restrictions.
On this reflector there is a tendency for most of the discussions to be
associated with high end stations with stacked beams, Big 4-squares,
multiple towers and beverages hundreds of feet long. Discussion is heavily
slanted towards systems requiring lots of space and a healthy bank account.
Perhaps this is reasonable since this is an adjunct of a contest oriented
web site. However the reflector has developed into a great source of general
information for that essential system which lives outside the window.
There are many contributors highly qualified and experienced in antenna
theory and practice. It would be a great service to large numbers of the
world wide ham population if some of these antenna gurus would consider
dreaming up some solutions to this universal problem or airing their
experiences here. Maybe we could get some more P5's etc on the air as a
result?
Thanks to all who have made this reflector one of the more useful and
enjoyable.
John AB4ET
teamw@quixnet.net
>>
You hvae very good points. No matter how small the lot the idea I suggested
of using a small deridgible to hold up a 1/2 wave wire fed j-pole fed on
160-40M is a simple solution and--it doesn't require all those radials. It's
great for contests on 160M anywhere. The 1/4 wave J gets it's major field up
off the ground a 1/2 wave. You could go ever higher.
You can also run a "Green Insulated Wire" along fence lines of the neigbors
for a Beverage. Match it with an L network. It even works on xmit. The top
wire of fences can be put into service (at night) with small insulators with
a little creativity. You can use the ground side of the 110 VAC for recieve
also on the BC band-40M. Use a series .1 ufd and then a 3 gang BC variable
for peaking. There are some very strong LF singals "down under." Years past
the receiver manuals showed a wire from a ground rod connected to the "G"
terminal and a 75' wire connected to the "A" terminal. I found out in the
30's they had it all wrong on the BC band and a bit higher. Connect the
ground lead to the "A" terminal with the series BC 3 gang variable. You can
still do it now in 2001. I had a 25' wire going to a buried oil tank for a
ground. It worked very well on recieve on 160M so I gave it a try on xmit
with my IC-720. It tuned to a 1.2:1 SWR. It should tune with most tuners in
the rigs now. At 7 PM in the evening in the fall I worked a W6 in the Bay
area from Seattle with a S7 report. I told him I was working him "ground
wave" and I had to explain.
Another trick that works is to run 136 of wire 10' off the ground on the
property boundries around a corner if necessary on small lots to a very good
ground (bury an old oil tank or a copper sheet of about 9 sq ft 6' udner the
ground horizontal). The Lo-Z there on all bands reflects back to the end of
the wire (1/2 wave multiple on all bands) for an easy match. Make it 160'
for BC SW listening from 3 MHz. Use the BC variable for peaking. For those
that don't know what a BC variable is and there are many, it's the 3 gang
variable used in BC radios years ago with 365 uufd capacity in each gang--tie
them together. They can still be found in flee markets. There are a few
left--I haven't purchased them all as yet. They work great in 100W L
networks and don't arc with Zloads less than about 1000 ohms. If you remove
plates in a "certain stagered manner" it becomes about 60 uufd per section
and can be used in transmitter finals up to about 500W and L networks with
Hi-Z loads.
One ham lived next to a water tower and gamma matched it. I have one 1 mile
away out in the county (with burried power lines) and have visions of a
beverage to it and using it as a 600 ohm termination. It would create a new
kind of "Fire Water" to the farm yards. The cattle would do a new type of
"SSB Fire Water Dance" after a drink and have a "certain glow" over them.
Would you believe that Iron wood and silver maple trees can be gamma matched
by bending down a limb fir a "LimbOmatch." That's even shown in some Army
Manuals. The root radial system is all right there. Pine trees tend to make
"Log Periodics" for high angle. k7gco
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