Bruno wrote:
Hi all,

I've had a planning application for a tower turned down which is a real
pain. My options are now very limited. I'm in a bungalow with a roof apex
height of 18 feet and I'm not allowed to put up anything much above this
roof line it transpires, so inverted vees that need to be mounted high up
at the feed point like G5RVs are not possible for me. My garden
boundaries limit the length of any wire antenna I might wish to put up to
about 120 feet overall. On the plus side, though, the QTH is several
hundred feet ASL close to the top of the hill and am not overshadowed by
any trees or buildings to speak of.
What's my best choice for an HF antenna under these circs? (I mostly do
CW on 20m & 40m, but would like a bit more band choice ideally if poss).
Many thanks.

Many thanks.

Verticals; if you have a lot of area, phased vertical arrays.


--
Jim Pennino

On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote:

Verticals; if you have a lot of area, phased vertical arrays.

Aren't verticals more inclined to generate interference?
BTW, my plot is 120' by 90' so I think an array at HF will be impossible.
The feed point will be pretty much central to the plot, though.

Bruno wrote:
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote:

Verticals; if you have a lot of area, phased vertical arrays.

Aren't verticals more inclined to generate interference?

No.

BTW, my plot is 120' by 90' so I think an array at HF will be impossible.
The feed point will be pretty much central to the plot, though.

A 40M four square would be a push, but a 20M a slam dunk.

DXEngineering has a lot of stuff and info for building various vertical
arrays with phased feeding.

The simplest array is 3 verticals about .23 lambda tall spaced at about
..34 lambda with just the center one fed.

With the other two undrounded, you get a typical, omnidirectional vertical
pattern.

If you ground the outer two (think remote relays) you get a broadside
pattern like a dipole with about 3.5 dBi gain.

Of course your ground will make a difference and likely the more radials
you can bury the better it will be unless you live in a swamp.

Verticals want a good ground, horizontals want a better than .5 lambda
height.



--
Jim Pennino

On Sunday, January 18, 2015 at 4:08:31 PM UTC-6, Bruno wrote:
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote:

Verticals; if you have a lot of area, phased vertical arrays.

Aren't verticals more inclined to generate interference?
BTW, my plot is 120' by 90' so I think an array at HF will be impossible.
The feed point will be pretty much central to the plot, though.

I would probably string up parallel coax fed dipoles and have them at
the low height. IE: 18-20 feet off the ground if that's all you can do.
They will still work fairly well overall. Say if you can stick a short
1-2 ft stub mast on the roof, run dipoles from it, and feed with a single
coax for both bands. Run the legs out to wherever you can tie them off.
IE: trees, or short masts in the back yard/garden, etc.
Won't be a gang buster DX setup, but plenty good enough for general use.
With 40 and 20 dipoles, you would also have 15 meters, running the
40 legs. And you can feed more dipoles from the same coax if you
want more bands.
Using the coax as a feed line, no tuner required and low system losses.
And also no need to worry about laying out radials.

wrote:
On Sunday, January 18, 2015 at 4:08:31 PM UTC-6, Bruno wrote:
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote:

Verticals; if you have a lot of area, phased vertical arrays.

Aren't verticals more inclined to generate interference?
BTW, my plot is 120' by 90' so I think an array at HF will be impossible.
The feed point will be pretty much central to the plot, though.

I would probably string up parallel coax fed dipoles and have them at
the low height. IE: 18-20 feet off the ground if that's all you can do.
They will still work fairly well overall. Say if you can stick a short
1-2 ft stub mast on the roof, run dipoles from it, and feed with a single
coax for both bands. Run the legs out to wherever you can tie them off.
IE: trees, or short masts in the back yard/garden, etc.
Won't be a gang buster DX setup, but plenty good enough for general use.
With 40 and 20 dipoles, you would also have 15 meters, running the
40 legs. And you can feed more dipoles from the same coax if you
want more bands.
Using the coax as a feed line, no tuner required and low system losses.
And also no need to worry about laying out radials.

At that height most of the energy goes straight up, so it will be a
NVIS antenna mostly suited for short ranges.


--
Jim Pennino

On Sunday, January 18, 2015 at 8:16:04 PM UTC-6, wrote:
wrote:
On Sunday, January 18, 2015 at 4:08:31 PM UTC-6, Bruno wrote:
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote:

Verticals; if you have a lot of area, phased vertical arrays.

Aren't verticals more inclined to generate interference?
BTW, my plot is 120' by 90' so I think an array at HF will be impossible.
The feed point will be pretty much central to the plot, though.

I would probably string up parallel coax fed dipoles and have them at
the low height. IE: 18-20 feet off the ground if that's all you can do.
They will still work fairly well overall. Say if you can stick a short
1-2 ft stub mast on the roof, run dipoles from it, and feed with a single
coax for both bands. Run the legs out to wherever you can tie them off.
IE: trees, or short masts in the back yard/garden, etc.
Won't be a gang buster DX setup, but plenty good enough for general use.
With 40 and 20 dipoles, you would also have 15 meters, running the
40 legs. And you can feed more dipoles from the same coax if you
want more bands.
Using the coax as a feed line, no tuner required and low system losses.
And also no need to worry about laying out radials.

At that height most of the energy goes straight up, so it will be a
NVIS antenna mostly suited for short ranges.


--
Jim Pennino

Sure. But it will still be able to work some DX, particularly on 20m,
and 15m using the 40 legs.
I guess it depends a lot on the type of operating he does.
If he wants general purpose, and maybe more leaning to NVIS for 40m
rag chewing, I'd go the dipole.
If he wants DX over NVIS, he may well be better off with a vertical.
But even a low dipole can be fairly good on the higher bands.
I remember camping once with a 40m dipole about 8-10ft off the ground,
and having no trouble working JA's on 15m using the same low antenna.
For 40m NVIS within 500 miles or so, the low dipole will likely smoke
most verticals.

I've run so many low dipoles, I can't count them all. Never had trouble
operating with any of them. And the setup is fairly simple.
The thing about verticals, they tend to be fairly lackluster for closer
in work on the lower bands. And I work much more rag chew NVIS type stuff
than DX. I'm actually not interested in DX much at all any more.
Been there, done that.. So it's kind of boring to me these days..

I tend to mostly jibber jabber to people I know these days, and work mostly
close in 160/80/40.. Which for my type of operating, the dipoles usually do
a good bit better than the verticals, even if fairly low.

I guess he'll have to decide what he wants to lean to. Whatever he decides
is unlikely to excel at both, and will be a compromise.

wrote:
On Sunday, January 18, 2015 at 8:16:04 PM UTC-6, wrote:
wrote:
On Sunday, January 18, 2015 at 4:08:31 PM UTC-6, Bruno wrote:
On Sun, 18 Jan 2015 21:28:07 +0000, jimp wrote:

Verticals; if you have a lot of area, phased vertical arrays.

Aren't verticals more inclined to generate interference?
BTW, my plot is 120' by 90' so I think an array at HF will be impossible.
The feed point will be pretty much central to the plot, though.

I would probably string up parallel coax fed dipoles and have them at
the low height. IE: 18-20 feet off the ground if that's all you can do.
They will still work fairly well overall. Say if you can stick a short
1-2 ft stub mast on the roof, run dipoles from it, and feed with a single
coax for both bands. Run the legs out to wherever you can tie them off.
IE: trees, or short masts in the back yard/garden, etc.
Won't be a gang buster DX setup, but plenty good enough for general use.
With 40 and 20 dipoles, you would also have 15 meters, running the
40 legs. And you can feed more dipoles from the same coax if you
want more bands.
Using the coax as a feed line, no tuner required and low system losses.
And also no need to worry about laying out radials.

At that height most of the energy goes straight up, so it will be a
NVIS antenna mostly suited for short ranges.


--
Jim Pennino

Sure. But it will still be able to work some DX, particularly on 20m,
and 15m using the 40 legs.
I guess it depends a lot on the type of operating he does.
If he wants general purpose, and maybe more leaning to NVIS for 40m
rag chewing, I'd go the dipole.
If he wants DX over NVIS, he may well be better off with a vertical.
But even a low dipole can be fairly good on the higher bands.
I remember camping once with a 40m dipole about 8-10ft off the ground,
and having no trouble working JA's on 15m using the same low antenna.
For 40m NVIS within 500 miles or so, the low dipole will likely smoke
most verticals.

Of course it will as all the energy will go straight up while the
vertical main lobe is at about 30 degrees.

The important factor is the height in wavelengths, not feet. As the
height drops below a half wavelength the main lobe goes vertical
on a dipole (or any horizontal antenna) rapidly.

I've run so many low dipoles, I can't count them all. Never had trouble
operating with any of them. And the setup is fairly simple.
The thing about verticals, they tend to be fairly lackluster for closer
in work on the lower bands. And I work much more rag chew NVIS type stuff
than DX. I'm actually not interested in DX much at all any more.
Been there, done that.. So it's kind of boring to me these days..

I tend to mostly jibber jabber to people I know these days, and work mostly
close in 160/80/40.. Which for my type of operating, the dipoles usually do
a good bit better than the verticals, even if fairly low.

I guess he'll have to decide what he wants to lean to. Whatever he decides
is unlikely to excel at both, and will be a compromise.

If local communications is your goal, then an NVIS antenns is what you
want. However as the frequency increases above about 8 MHz the
probablity for success decreases and drops to near zero at 30 MHz. For
20 meters it is a crap shoot with less than good sunspot activity.

I don't really see how a dipole requiring three supports, two at best,
can be considered simpler than a vertical with one support.


--
Jim Pennino

On Monday, January 19, 2015 at 12:31:04 AM UTC-6,
For 40m NVIS within 500 miles or so, the low dipole will likely smoke
most verticals.

Of course it will as all the energy will go straight up while the
vertical main lobe is at about 30 degrees.

The important factor is the height in wavelengths, not feet. As the
height drops below a half wavelength the main lobe goes vertical
on a dipole (or any horizontal antenna) rapidly.

Sure, but there is still enough at the low angles to make some DX
contacts. And he'll have a decent signal to the stations not so far
away on 40m.




I guess he'll have to decide what he wants to lean to. Whatever he decides
is unlikely to excel at both, and will be a compromise.

If local communications is your goal, then an NVIS antenns is what you
want. However as the frequency increases above about 8 MHz the
probablity for success decreases and drops to near zero at 30 MHz. For
20 meters it is a crap shoot with less than good sunspot activity.

The performance at low angles won't be quite as grim as you might expect.
IE: I had no trouble working 15m DX with a -10 ft high dipole. 20 ft up is
nearly a 1/2 on 15m. And a 20m dipole at 20 ft will be quite decent for
average use being over a 1/4 wave up. Will be good stateside, and usable
for DX. I like converted CB ground planes for 10m. Good space wave for
local, and good for DX. Not much close in sky wave stuff to work on that
band.


I don't really see how a dipole requiring three supports, two at best,
can be considered simpler than a vertical with one support.

A vertical generally needs radials unless it's a "1/2 wave" type
design. And even good verticals can be quite lackluster for close
in work compared to a low dipole on 40m. Good at night to DX though.
But like I say, he's gotta decide what he wants to concentrate on,
and go from there.

If he has trees to tie dipole legs to, he really only needs one
support for the apex. And one can also string them between trees
to where no man made supports are needed at all.
But I don't know what trees he has available.

I usually have one mast for the apex, and tie off to trees or whatever.
At the dirt patch, I use a oak tree as the apex support, and tie
off to other trees. I shoot a weighted line up into the apex tree,
and run it over a tall branch. Then I pull the dipole and coax back
up into the tree with the wire I shot over the tall branch.
When I go home, I let the wire loose, and back down it all falls.
I used to leave it there all the time, but the critters were eating
my coax into shreds, so I had to quit that. :/

And the tuner/ladder line fed dipoles is another option if one wants
all bands with one antenna.