I am seriously lusting over the concept of putting together a
foursquare array of 40M verticals.

I found the http://www.zerofive-antennas.com/ website and the antenna
part looks do-able. If a bit heavy-duty!

I think I have the space in the yard to put down the radials. The
house gets in the way of one direction but I think I can put down at
least quarter-wavelength radials from each base in all directions and
half-wavelength or longer in some other directions.

I have some old ARRL antenna handbooks with articles by Roy Lewallen
about phasing arrays and measurements. I also have EZNEC. Is there
something I can do to prove to myself that having my house on one side
of the array and the edge of my lot on the other side of the array,
resulting in a radial plane that's not radial but more like a
rectangle, won't mess up the whole concept?

And if I draw things out it looks like an 80M foursquare array would
be possible but my house would be in the middle of it :-). Is this a
recipe for disaster or would it actually work? (Not that I could
afford four 75-foot vertical radiators from zerofive, but I can
imagine!)

Tim.

On Mon, 15 Oct 2007 08:47:16 -0700, Tim Shoppa
wrote:

I think I can put down at
least quarter-wavelength radials from each base in all directions and
half-wavelength or longer in some other directions.

Hi Tom,

Radials, on/in the ground, do not need to be fractional wavelength
multiples (eighth, quarter, half...). Length = radiator height is
fine, shorter and more is roughly equivalent.

Is there
something I can do to prove to myself that having my house on one side
of the array and the edge of my lot on the other side of the array,
resulting in a radial plane that's not radial but more like a
rectangle, won't mess up the whole concept?

No, probably not. And if it proved anything, what could you do about
it anyway?

And if I draw things out it looks like an 80M foursquare array would
be possible but my house would be in the middle of it :-). Is this a
recipe for disaster or would it actually work?

No, not a disaster. It probably might/might-not work.

Radials are for matching and efficiency. They do impact lobe shape,
but in the scheme of things (a four-square) you are already managing
that detail and the lobe offsets probably average out anyway.

What I mean is that if you located each element in the corner of your
lot (hypothetical, as set-backs for neighbors and guying will probably
force another configuration); then you would have a radial field at
each one that could only fill 90 degrees of the circle expected at
each (for a pristine, factory guaranteed installation). The lack of
3/4ths of those radials would bring loss. The lack of 3/4ths of those
radials would reduce signal strength in those un-radialed directions.

However, you have three others that do point in those directions
filling in all 4/4ths - as an average. You still suffer the ground
loss, true, but the ground coverage you do have probably stiffens the
system sufficiently to exhibit the expected beam forming - I presume
this is the feature you are after.

73's
Richard Clark, KB7QHC

Let me second Richard's comments about radials needing to be some
specific fraction of a wave - not....
Just put down the radials you can manage... If it isn't a perfect
circle around the antenna, don't even think about it, put the radials
down and enjoy your antenna..
Don't measure them, just pace them out from the antenna, cut and
secure the end, step sideways, secure another end and pace back to the
antenna, repeat... Whatever you get down will work...
Read, K3LR's comments about putting up a low 160 inverted L for an
impromptu contest while on vacation, having just two 1/4W radials and
working 40 some states and a bunch of countries...
So, assuming you can get down 20 or more radials under each vertical,
the 4 square will work...
If you could get down lots more radials the 4 square will work a bit
better on weak signals (strong signals won't notice how many radials
you have down)
If you could get down 120 'full wave' radials, the 4 square will work
the very best it can be (roughly 2 ohms series resistance on the
ground circuit)...
But after 50 radials of random length, you will be hard pressed to
tell any difference between that and the 120 radial 'perfect' ground
plane...

cheers ...
denny/k8do

On 16 Oct, 04:16, Denny wrote:
Let me second Richard's comments about radials needing to be some
specific fraction of a wave - not....
Just put down the radials you can manage... If it isn't a perfect
circle around the antenna, don't even think about it, put the radials
down and enjoy your antenna..
Don't measure them, just pace them out from the antenna, cut and
secure the end, step sideways, secure another end and pace back to the
antenna, repeat... Whatever you get down will work...
Read, K3LR's comments about putting up a low 160 inverted L for an
impromptu contest while on vacation, having just two 1/4W radials and
working 40 some states and a bunch of countries...
So, assuming you can get down 20 or more radials under each vertical,
the 4 square will work...
If you could get down lots more radials the 4 square will work a bit
better on weak signals (strong signals won't notice how many radials
you have down)
If you could get down 120 'full wave' radials, the 4 square will work
the very best it can be (roughly 2 ohms series resistance on the
ground circuit)...
But after 50 radials of random length, you will be hard pressed to
tell any difference between that and the 120 radial 'perfect' ground
plane...

cheers ...
denny/k8do

Exactly! All you are doing is providing a low impedance
to ground so the return current gets back to transmitter ground
instead of the travelling up the outside of the coax.
Myths are really hard to put down
Art

On Oct 16, 2:50?pm, art wrote:
On 16 Oct, 04:16, Denny wrote:





Let me second Richard's comments about radials needing to be some
specific fraction of a wave - not....
Just put down the radials you can manage... If it isn't a perfect
circle around the antenna, don't even think about it, put the radials
down and enjoy your antenna..
Don't measure them, just pace them out from the antenna, cut and
secure the end, step sideways, secure another end and pace back to the
antenna, repeat... Whatever you get down will work...
Read, K3LR's comments about putting up a low 160 inverted L for an
impromptu contest while on vacation, having just two 1/4W radials and
working 40 some states and a bunch of countries...
So, assuming you can get down 20 or more radials under each vertical,
the 4 square will work...
If you could get down lots more radials the 4 square will work a bit
better on weak signals (strong signals won't notice how many radials
you have down)
If you could get down 120 'full wave' radials, the 4 square will work
the very best it can be (roughly 2 ohms series resistance on the
ground circuit)...
But after 50 radials of random length, you will be hard pressed to
tell any difference between that and the 120 radial 'perfect' ground
plane...

cheers ...
denny/k8do

Exactly! All you are doing is providing a low impedance
to ground so the return current gets back to transmitter ground
instead of the travelling up the outside of the coax.
Myths are really hard to put down
Art- Hide quoted text -

- Show quoted text -

Hi Tm
I have a 40 meter 4 square special on my web site if you would like to
check it out.
I also have guyed 80 meter verticals ,They are 1/2 the cost of the
freestanding ones.
Contact me if you have any questions.

TOM
N9ZV