I have a 6BTV that I'm about to install. It will primarily be used for
80/40/30 meters. Some questions:

I could elevate it, if it would improve performance. The manual says not to
ground the radials or the antenna base, so I could mount the unit on an
insulated mast, and string the radials at a 45 degree angle....

Or I could place it near the ground, or try a metal mast, or....

Any experience/suggestions?

Gary K5QT

My 2 cents -- my experience with 1/4 wave verticals with ground radials has
been pretty miserable. With many many radials and good ground would probably
be Ok.

When I put the 1/4 wave up on the roof with four radials slightly
drooping -- wow what an improvement.

Also I have had good luck with the Cushcraft end fed antennas with no
radials

Your radiation may vary - hi hi

--
Lamont Cranston

The Shadow Knows
"AA5QT" wrote in message
...
I have a 6BTV that I'm about to install. It will primarily be used for
80/40/30 meters. Some questions:

I could elevate it, if it would improve performance. The manual says not
to
ground the radials or the antenna base, so I could mount the unit on an
insulated mast, and string the radials at a 45 degree angle....

Or I could place it near the ground, or try a metal mast, or....

Any experience/suggestions?

Gary K5QT

"Bill Turner" wrote -
Performance will be best if it's up in the air, away from ground. RF
does best when flowing through metal, not dirt. Earth is lossy and
should be avoided for transmitting. If you were receiving only, the
loss could be made up by more gain in the receiver, but when power is
lost during transmitting, it's gone forever.

If for some reason you 'had' to mount the vertical at ground level, you
should install enough radials that the antenna does not 'see' the earth
at all, only the radials. To do this, the generally accepted number of
radials is about 120, 1/4 wave long.

===============================

Fine on your comments Bill except for the oft-repeated number of 120 which
must have been originated by Marzipan the Magician. It is far too
extravagant.

For amateur purposes 32 radials are 'enough'. And that only because it's
twice 16, which is twice 8 - - - - down to 2 which is twice 1.

Over a wide range of soil resistivities and radial lengths, the
electrode-to-ground resistance of 32 radials is only about 1.3 times that of
a solid copper disk of the same radius laid flat on the ground.

The electrode-to-ground resistance of 1 radial is about 6 or 7 times that of
32 radials so unless immersed in salt water it may be well worth while
increasing to 4, 8, 16 or even 32.

In average soils and with radial lengths of around 20 metres, the electrode
resistance of 32 radials will already be as low as 3 ohms which is perfectly
good enough for less than a 1/4-wave or 5/8-wave vertical and far better
than necessary for a 1/2-wave vertical. To increase to 120 or more radials
is just a waste of good copper plus a lot of hard labour.

The following table is for a typical ground resistivity = 200 ohm-meters
(conductivity = 5 milli-Siemens), radial length = 66 feet, wire diameter =
14 awg, buried depth = 1 inch.

Radials ohms
--------- -------
1 24.6
2 13.6
4 8.0
8 5.3
16 4.2
32 3.3
64 2.8
128 2.7
Disk 2.5

For a 1/4-wave vertical I wouldn't bother with more than 16 radials with
which efficiency is of the order of 90 percent. Or an undetectable 1/12 of
an S-unit less than perfection.

If ground resistivity is not known, as it nearly always isn't, then a
logical way to proceed is to keep doubling up the number of radials until
the received signal strength of not too distant stable transmissions stops
increasing. Then add 2 or 3 more for luck. But I doubt whether the new magic
number of 32 will be exceeded.

Regarding length of radials. The propagation velocity along wires buried in
the ground is very much smaller than in free space. When lying on the
surface of the ground it about half the free space value. So surface
radials need never be longer than 1/8 wavelengths.

Furthermore, the loss along buried wires is very high. Of the order of 8 dB
per 1/4-wavelength at their own velocity. So there's little point in having
buried wires much longer than 10 meters or 33 feet on the 160m band, and
progressively shorter lengths at higher frequencies. At distances where
there's no current flowing in the wires there's no point in them being
there. Nobody uses ground radials for 15 and 10 meters anyway.

Do I hear anybody shouting "Heretic" ? ;o)
----
Reg, G4FGQ.

If I interpreted the manual correctly, it indicates one should insulate the
antenna base from a pole or tower that is nearing 1/4 wavelength. It didn't
seem to caution against conventional mounting if the tower or support pole was a
different length....

The manual seems to provide reasonable information regarding the use of radials
at 45 degree droop, recommending their use if possible. Ground mounting is
generally noted as being less desirable than roof or elevated mount with 45
degree radials...

I have a 5BTV and the antenna on the higher bands (10, 15, 20, 40) has
reasonable bandwidth, but on 75 meters the bandwidth is extremely narrow, do
much so it is nearly useless unless you have a single frequency you normally
use... Sitting on the ground, using two radials per band provides acceptable
performance on 10-40m, but on 80, it took 4 radials to get the swr down to
1.5:1, and even then, the bandwidth between the 2.0 swr points is only about 60
khz at best. You really need to pick your operating frequency for 80m. In a
few weeks I'm going to try to roof mount it to see if I can get a wider
bandwidth on 80m.

Good Luck!

--Rick AH7H


AA5QT wrote:

I have a 6BTV that I'm about to install. It will primarily be used for
80/40/30 meters. Some questions:

I could elevate it, if it would improve performance. The manual says not to
ground the radials or the antenna base, so I could mount the unit on an
insulated mast, and string the radials at a 45 degree angle....

Or I could place it near the ground, or try a metal mast, or....

Any experience/suggestions?

Gary K5QT

Damn!!
I thought I was reading a paper from K2RIW!!!!
Lots of good stuff hear!!
73

Reg Edwards wrote:

"Bill Turner" wrote -
Performance will be best if it's up in the air, away from ground. RF
does best when flowing through metal, not dirt. Earth is lossy and
should be avoided for transmitting. If you were receiving only, the
loss could be made up by more gain in the receiver, but when power is
lost during transmitting, it's gone forever.

If for some reason you 'had' to mount the vertical at ground level, you
should install enough radials that the antenna does not 'see' the earth
at all, only the radials. To do this, the generally accepted number of
radials is about 120, 1/4 wave long.

===============================

Fine on your comments Bill except for the oft-repeated number of 120 which
must have been originated by Marzipan the Magician. It is far too
extravagant.

For amateur purposes 32 radials are 'enough'. And that only because it's
twice 16, which is twice 8 - - - - down to 2 which is twice 1.

Over a wide range of soil resistivities and radial lengths, the
electrode-to-ground resistance of 32 radials is only about 1.3 times that of
a solid copper disk of the same radius laid flat on the ground.

The electrode-to-ground resistance of 1 radial is about 6 or 7 times that of
32 radials so unless immersed in salt water it may be well worth while
increasing to 4, 8, 16 or even 32.

In average soils and with radial lengths of around 20 metres, the electrode
resistance of 32 radials will already be as low as 3 ohms which is perfectly
good enough for less than a 1/4-wave or 5/8-wave vertical and far better
than necessary for a 1/2-wave vertical. To increase to 120 or more radials
is just a waste of good copper plus a lot of hard labour.

The following table is for a typical ground resistivity = 200 ohm-meters
(conductivity = 5 milli-Siemens), radial length = 66 feet, wire diameter =
14 awg, buried depth = 1 inch.

Radials ohms
--------- -------
1 24.6
2 13.6
4 8.0
8 5.3
16 4.2
32 3.3
64 2.8
128 2.7
Disk 2.5

For a 1/4-wave vertical I wouldn't bother with more than 16 radials with
which efficiency is of the order of 90 percent. Or an undetectable 1/12 of
an S-unit less than perfection.

If ground resistivity is not known, as it nearly always isn't, then a
logical way to proceed is to keep doubling up the number of radials until
the received signal strength of not too distant stable transmissions stops
increasing. Then add 2 or 3 more for luck. But I doubt whether the new magic
number of 32 will be exceeded.

Regarding length of radials. The propagation velocity along wires buried in
the ground is very much smaller than in free space. When lying on the
surface of the ground it about half the free space value. So surface
radials need never be longer than 1/8 wavelengths.

Furthermore, the loss along buried wires is very high. Of the order of 8 dB
per 1/4-wavelength at their own velocity. So there's little point in having
buried wires much longer than 10 meters or 33 feet on the 160m band, and
progressively shorter lengths at higher frequencies. At distances where
there's no current flowing in the wires there's no point in them being
there. Nobody uses ground radials for 15 and 10 meters anyway.

Do I hear anybody shouting "Heretic" ? ;o)
----
Reg, G4FGQ.

Damn!!
I thought I was reading a paper from K2RIW!!!!
Lots of good stuff here!!
73

Reg Edwards wrote:

"Bill Turner" wrote -
Performance will be best if it's up in the air, away from ground. RF
does best when flowing through metal, not dirt. Earth is lossy and
should be avoided for transmitting. If you were receiving only, the
loss could be made up by more gain in the receiver, but when power is
lost during transmitting, it's gone forever.

If for some reason you 'had' to mount the vertical at ground level, you
should install enough radials that the antenna does not 'see' the earth
at all, only the radials. To do this, the generally accepted number of
radials is about 120, 1/4 wave long.

===============================

Fine on your comments Bill except for the oft-repeated number of 120 which
must have been originated by Marzipan the Magician. It is far too
extravagant.

For amateur purposes 32 radials are 'enough'. And that only because it's
twice 16, which is twice 8 - - - - down to 2 which is twice 1.

Over a wide range of soil resistivities and radial lengths, the
electrode-to-ground resistance of 32 radials is only about 1.3 times that of
a solid copper disk of the same radius laid flat on the ground.

The electrode-to-ground resistance of 1 radial is about 6 or 7 times that of
32 radials so unless immersed in salt water it may be well worth while
increasing to 4, 8, 16 or even 32.

In average soils and with radial lengths of around 20 metres, the electrode
resistance of 32 radials will already be as low as 3 ohms which is perfectly
good enough for less than a 1/4-wave or 5/8-wave vertical and far better
than necessary for a 1/2-wave vertical. To increase to 120 or more radials
is just a waste of good copper plus a lot of hard labour.

The following table is for a typical ground resistivity = 200 ohm-meters
(conductivity = 5 milli-Siemens), radial length = 66 feet, wire diameter =
14 awg, buried depth = 1 inch.

Radials ohms
--------- -------
1 24.6
2 13.6
4 8.0
8 5.3
16 4.2
32 3.3
64 2.8
128 2.7
Disk 2.5

For a 1/4-wave vertical I wouldn't bother with more than 16 radials with
which efficiency is of the order of 90 percent. Or an undetectable 1/12 of
an S-unit less than perfection.

If ground resistivity is not known, as it nearly always isn't, then a
logical way to proceed is to keep doubling up the number of radials until
the received signal strength of not too distant stable transmissions stops
increasing. Then add 2 or 3 more for luck. But I doubt whether the new magic
number of 32 will be exceeded.

Regarding length of radials. The propagation velocity along wires buried in
the ground is very much smaller than in free space. When lying on the
surface of the ground it about half the free space value. So surface
radials need never be longer than 1/8 wavelengths.

Furthermore, the loss along buried wires is very high. Of the order of 8 dB
per 1/4-wavelength at their own velocity. So there's little point in having
buried wires much longer than 10 meters or 33 feet on the 160m band, and
progressively shorter lengths at higher frequencies. At distances where
there's no current flowing in the wires there's no point in them being
there. Nobody uses ground radials for 15 and 10 meters anyway.

Do I hear anybody shouting "Heretic" ? ;o)
----
Reg, G4FGQ.

"Steve" wrote
Damn!!
I thought I was reading a paper from K2RIW!!!!
Lots of good stuff here!!
73

===============================

I am not familiar with what K2RIW has to say about ground systems, sets of
ground radials, etc. You must be familiar yourself. I would like to learn
more about what he has to say. Could you please direct me into the right
K2RIW channels?

and oblige Reg, G4FGQ

Rick,
I suspect that '60 Khz' was a slip of the typing
fingers, 'cuz that ain't bad for a 5btv on 80 meters.
Most commercial vertical antennas that cover 80 meters
(and some on 40 meters) have a very narrow range. The
5BTV is no exception...
'Doc

Bill has overstated the "generally accepted" number of radials. AM broadcast
stations will have 120 radials but I've never met a ham with that many and
many thousands of us have worked the world with a lot fewer. It depends
greatly on the quality of ground you have and that's not easy to determine
before you begin. But after 8 radials, improvements with each additional
radial become much smaller.

My advice, Gary, is to start with a few radials for each band and try it
out. Here's the irony: if that works well, you will probably see an
improvement if you double the number of radials. If it doesn't work well at
all, you might try a different approach because adding more radials will not
be too effective.

Nature is full of these ironies. My favorite is that when bread and crackers
are exposed to the same environment, the bread becomes hard and the crackers
become soft! (Posted on someone's door at Stanford Research Institue back in
the 60's.)

Chuck

"Bill Turner" wrote in message
...
On 20 Jun 2004 13:52:17 GMT, (AA5QT) wrote:

I have a 6BTV that I'm about to install. It will primarily be used for
80/40/30 meters. Some questions:

I could elevate it, if it would improve performance. The manual says not
to
ground the radials or the antenna base, so I could mount the unit on an
insulated mast, and string the radials at a 45 degree angle....

Or I could place it near the ground, or try a metal mast, or....

Any experience/suggestions?

Gary K5QT

__________________________________________________ _______

Performance will be best if it's up in the air, away from ground. RF
does best when flowing through metal, not dirt. Earth is lossy and
should be avoided for transmitting. If you were receiving only, the
loss could be made up by more gain in the receiver, but when power is
lost during transmitting, it's gone forever.

If for some reason you 'had' to mount the vertical at ground level, you
should install enough radials that the antenna does not 'see' the earth
at all, only the radials. To do this, the generally accepted number of
radials is about 120, 1/4 wave long.

--
Bill, W6WRT
QSLs via LoTW

Bill has overstated the "generally accepted" number of radials. AM broadcast
stations will have 120 radials but I've never met a ham with that many and
many thousands of us have worked the world with a lot fewer. It depends
greatly on the quality of ground you have and that's not easy to determine
before you begin. But after 8 radials, improvements with each additional
radial become much smaller.

My advice, Gary, is to start with a few radials for each band and try it
out. Here's the irony: if that works well, you will probably see an
improvement if you double the number of radials. If it doesn't work well at
all, you might try a different approach because adding more radials will not
be too effective.

Nature is full of these ironies. My favorite is that when bread and crackers
are exposed to the same environment, the bread becomes hard and the crackers
become soft! (Posted on someone's door at Stanford Research Institue back in
the 60's.)

Chuck

"Bill Turner" wrote in message
...
On 20 Jun 2004 13:52:17 GMT, (AA5QT) wrote:

I have a 6BTV that I'm about to install. It will primarily be used for
80/40/30 meters. Some questions:

I could elevate it, if it would improve performance. The manual says not
to
ground the radials or the antenna base, so I could mount the unit on an
insulated mast, and string the radials at a 45 degree angle....

Or I could place it near the ground, or try a metal mast, or....

Any experience/suggestions?

Gary K5QT

__________________________________________________ _______

Performance will be best if it's up in the air, away from ground. RF
does best when flowing through metal, not dirt. Earth is lossy and
should be avoided for transmitting. If you were receiving only, the
loss could be made up by more gain in the receiver, but when power is
lost during transmitting, it's gone forever.

If for some reason you 'had' to mount the vertical at ground level, you
should install enough radials that the antenna does not 'see' the earth
at all, only the radials. To do this, the generally accepted number of
radials is about 120, 1/4 wave long.

--
Bill, W6WRT
QSLs via LoTW