Hi all, I am just about to get my Foundation licence and am contemplating a
multiband vertical. Many plan talks about "radials" being needed, now I just
happen to have a house with a nice tin roof. Can I make use of the whole
roof as a ground plain or do I need radials cut to resonance for each band?

Thank

Andre (vk3 - almost got it!!!)

"Andre & Sharon Walker" wrote in
:

Hi all, I am just about to get my Foundation licence and am
contemplating a multiband vertical. Many plan talks about "radials"
being needed, now I just happen to have a house with a nice tin roof.
Can I make use of the whole roof as a ground plain or do I need
radials cut to resonance for each band?


Do you mean a trapped vertical or the like, or are you planning to use an
unloaded vertical on multiple bands.

If it is a trapped vertical, it probably comes with instructions. For
example, http://www.dxengineering.com/pdf/hus...5btv_instl.pdf
details the installation instructions for the Huster verticals.

You could read the instructions / manual after it doesn't work properly,
or you could read them beforehand.

Not all verticals require a substantial ground system, it depends on the
design. The tin roof might well provide a sufficient counterpoise for
some trapped verticals, depending on its size and location of the
antenna.

Short verticals are invariably quite narrow band on low bands, often as
little as 20kHz on 80m.

Also, keep in mind that verticals are relatively noisy in city
environments.

You might be well served with a simple coax fed dipole for one band (40m)
initially. Gain some experience, and note how many others are using
trapped verticals or the like. Do try to resist the end fed long wire
(though it is more correctly described as an end fed random length wire)
that seems so popular with FLs.

Owen

Owen Duffy wrote:
You might be well served with a simple coax fed dipole for one band (40m)
initially.

A similar antenna, but one step closer to multiband operation
would be a simple dipole for one band (40m) fed with a multiple
of 1/2 wavelengths of ladder-line. At the resonant frequency,
it is hard to tell from a coax-fed dipole and an antenna
tuner will allow coverage of the entire band. The bonus is
that such an antenna can be made to work well on all ham
frequencies above the design frequency. If one is willing
to vary the length of the ladder-line, one can get by
without a conventional antenna tuner. Info at:

http://www.w5dxp.com/notuner.htm
--
73, Cecil http://www.w5dxp.com

I was hoping to get away from traps, but i dont think its possible :-(. I
only have a smallish yard, with just 30m from the chimmny (brick ) to the
back of the yard, so i think a decent wire antenna is out...but i am open to
suggestions. I guess the other considerstion is to keep "she inside" happy .

Andre
"Andre & Sharon Walker" wrote in message
...
Hi all, I am just about to get my Foundation licence and am contemplating
a multiband vertical. Many plan talks about "radials" being needed, now I
just happen to have a house with a nice tin roof. Can I make use of the
whole roof as a ground plain or do I need radials cut to resonance for
each band?

Thank

Andre (vk3 - almost got it!!!)

Andre & Sharon Walker wrote:
I was hoping to get away from traps, but i dont think its possible :-(. I
only have a smallish yard, with just 30m from the chimmny (brick ) to the
back of the yard, so i think a decent wire antenna is out...but i am open to
suggestions. I guess the other considerstion is to keep "she inside" happy .

A 1/2WL dipole is 20m on 40m and can be made to work on
all HF bands 40m-10m. That's probably what I would do
and then do something romantic to keep the XYL happy.
--
73, Cecil http://www.w5dxp.com

My antenna is similar to yours, but slightly longer. I have a 110 feet
dipole running between my chimney and a tree at the back of the lot. The
dipole is at a height of 30 feet and is fed with open-wire. I use an antenna
tuner and the antenna works fairly well on all bands 80 through 10 meters.

John, N9JG

"Cecil Moore" wrote in message
.. .
Andre & Sharon Walker wrote:
I was hoping to get away from traps, but i dont think its possible :-(. I
only have a smallish yard, with just 30m from the chimmny (brick ) to the
back of the yard, so i think a decent wire antenna is out...but i am open
to
suggestions. I guess the other considerstion is to keep "she inside"
happy .

A 1/2WL dipole is 20m on 40m and can be made to work on
all HF bands 40m-10m. That's probably what I would do
and then do something romantic to keep the XYL happy.
--
73, Cecil http://www.w5dxp.com

John, N9JG wrote:
My antenna is similar to yours, but slightly longer. I have a 110 feet
dipole running between my chimney and a tree at the back of the lot. The
dipole is at a height of 30 feet and is fed with open-wire. I use an antenna
tuner and the antenna works fairly well on all bands 80 through 10 meters.

Your dipole is 8 feet longer than the G5RV length which
is a positive for 80m operation. For your favorite bands,
there is probably an optimum length of feedline. EZNEC
allows one to model different lengths of feedline. I
wrote a compiled BASIC DOS program that will estimate
the optimum lengths of feedline at:

http://www.w5dxp.com/imax.exe
--
73, Cecil http://www.w5dxp.com

What do you mean by optimum length since open-wire feedline has minimal
loss? When I moved into this property last July, I just strung the longest
wire that would fit into the lot, and reeled out the amount of feedline that
would reach between the tuner and my shack on the second floor. I can not
make the feedline appreciably shorter, and if I made it longer I would have
to figure out how to support the additional feedline. I estimate the
feedline has a length of 70 feet.

John, N9JG

"Cecil Moore" wrote in message
et...
John, N9JG wrote:
My antenna is similar to yours, but slightly longer. I have a 110 feet
dipole running between my chimney and a tree at the back of the lot. The
dipole is at a height of 30 feet and is fed with open-wire. I use an
antenna tuner and the antenna works fairly well on all bands 80 through
10 meters.

Your dipole is 8 feet longer than the G5RV length which
is a positive for 80m operation. For your favorite bands,
there is probably an optimum length of feedline. EZNEC
allows one to model different lengths of feedline. I
wrote a compiled BASIC DOS program that will estimate
the optimum lengths of feedline at:

http://www.w5dxp.com/imax.exe
--
73, Cecil http://www.w5dxp.com

Cecil Moore wrote in
:

Andre & Sharon Walker wrote:
I was hoping to get away from traps, but i dont think its possible
:-(. I only have a smallish yard, with just 30m from the chimmny
(brick ) to the back of the yard, so i think a decent wire antenna is
out...but i am open to suggestions. I guess the other considerstion
is to keep "she inside" happy .

A 1/2WL dipole is 20m on 40m and can be made to work on
all HF bands 40m-10m. That's probably what I would do
and then do something romantic to keep the XYL happy.

Cecil, Andre will not have access to most HF bands, just 80, 40, 15, and
10m.

It takes about 6 hours to train and assess a Foundation Licencee, so your
tunerless concept is perhaps more complex than Andre's current knowledge
base.

For example, I worked a FL chap a couple of days ago on 40m with a 80m
half wave dipole fed with a long run of coax, and he was confident that
his antenna worked real well, despite my expectation that it was likely
that well less than 10% of his permitted 10W PEP was radiated. It was
impossible to tell this chap that if he cut the dipole to half the length
it would work better on 40m.

It is no good telling people that an antenna isn't likely to work real
good, they will cite all the contacts that they have had with it, and as
we know, anything "works", doesn't it. However, most people listen to the
positive suggestion that with change, and antenna will work better (and
in the above case, more than 10 times the EIRP).

Andre, keep it simple. A coax fed half wave dipole is easy to get going
will limited knowledge and experience, and you should have a high
confidence that you will be able to deliver a suitable load to your
transmitter (ie it will deliver its rated power), and the antenna will be
quite efficient (ie that most of your 10W PEP transmitter power is
radiated). It will also work well on receive.

If you hear strong FL signals around, they have good antennas, and / or
are flaunting the power limit. It is easy to do the latter, but if you
get the antenna right, you still have the room for improvement when you
upgrade to the higher power limit.

Owen

Wow..looks like I opened a can of worms here!
Thanks to all for the many links and advice..much food for thought. I think
ill have to re assess I was considering end fed longwire also, but an
inverted V might be a better option. Anyway, should be on the air within 4
weeks...the licence is the easy bit, diverting funds for the radio from the
XYL is the tricky part!!! But ive been offered a FT101z , inc Yaseu Desk mix
+ spare set of finals ( is too early to rember the number of the tubes off
hand...just finished night shift), so ill have wind the wick WAY back to
start with. I don't care what they say at the club...I like boat anchors!!
( I'd love to replace the Murphy B40 I sold 10 years ago :-( )

Cheers

Andre
"Owen Duffy" wrote in message
...
Cecil Moore wrote in
:

Andre & Sharon Walker wrote:
I was hoping to get away from traps, but i dont think its possible
:-(. I only have a smallish yard, with just 30m from the chimmny
(brick ) to the back of the yard, so i think a decent wire antenna is
out...but i am open to suggestions. I guess the other considerstion
is to keep "she inside" happy .

A 1/2WL dipole is 20m on 40m and can be made to work on
all HF bands 40m-10m. That's probably what I would do
and then do something romantic to keep the XYL happy.

Cecil, Andre will not have access to most HF bands, just 80, 40, 15, and
10m.

It takes about 6 hours to train and assess a Foundation Licencee, so your
tunerless concept is perhaps more complex than Andre's current knowledge
base.

For example, I worked a FL chap a couple of days ago on 40m with a 80m
half wave dipole fed with a long run of coax, and he was confident that
his antenna worked real well, despite my expectation that it was likely
that well less than 10% of his permitted 10W PEP was radiated. It was
impossible to tell this chap that if he cut the dipole to half the length
it would work better on 40m.

It is no good telling people that an antenna isn't likely to work real
good, they will cite all the contacts that they have had with it, and as
we know, anything "works", doesn't it. However, most people listen to the
positive suggestion that with change, and antenna will work better (and
in the above case, more than 10 times the EIRP).

Andre, keep it simple. A coax fed half wave dipole is easy to get going
will limited knowledge and experience, and you should have a high
confidence that you will be able to deliver a suitable load to your
transmitter (ie it will deliver its rated power), and the antenna will be
quite efficient (ie that most of your 10W PEP transmitter power is
radiated). It will also work well on receive.

If you hear strong FL signals around, they have good antennas, and / or
are flaunting the power limit. It is easy to do the latter, but if you
get the antenna right, you still have the room for improvement when you
upgrade to the higher power limit.

Owen