45' high, 25.8 sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded.

Predicted Radiation Resistance: 25.8 ohms, very good ground (rich pastoral,
midwest).

With no radials, I get a flat 50 ohm match at 3595 khz. Obviously this would
indicate ground losses of approximately 25 ohms, if I'm thinking about this
right. Also, predicted efficiency would then be 50 % (25/(25+25), indicating
a 3 dB loss. Forgetting about fresnel region losses, this seems to be better
than I had expected. 2:1 vswr bandwidth is very broad....broader than what I
get with EZnec 4.x with a 25 ohm load in the base.

This means one of two things to me:

Either my ground losses are much higher than the 25 ohms I'm indirectly
calculating, or I have made some sort of conceptual error in thinking about
what the implications are of a 25 or 26 ohm feedpoint. All my references
point toward a 25 ohm radiation resistance for my 42' vertical x 25.8 ft
inverted L (with sloping top wire instead of flat top wire). What is wrong
with my logic here? If the R(rad) is 25 ohms, and I measure a flat VSWR (on
two other meters) at 3600 khz, then isn't the remaining 25 ohms, ground
loss?

I also show about 37 ohms resistance and 0 ohms reactance at 3600 khz with
my MFJ-269, which is really confusing, in that if I have 25 ohms for Rrad,
then I have 13 ohms of ground losses. Further, 37 ohms is around 1.3 to 1.
So I have two other vswr meters showing 1:1 at 3600, and the MFJ showing 37
ohms. This is a pretty large percentage difference.

I would be inclined to believe the 25.8 ohms predicted by both EZnec 4 and
the Low Band DX'rs Handbook. In any case, I'll put out 4 radials tomorrow
morning and repeat all my measurements, looking for narrowing bandwidth and
lowered input Z as my ground losses decrease.

Ultimately, I'm going to put down 16, 66' radials, in steps of four, taking
measurements of input Z (mfj-269) and vswr bandwidth for 2:1, at 0,4,8 and
16 radials. I'll report what happens as I go along.

Anywho, without any radials at all there are quite a few distant signals on
80m this evening, that are consistently louder on the newly installed
inverted L, than on my Carolina Windom at 45'. Most signals as one pans the
band, are louder (at 2 hours after sunset) on the C. Windom than on the
radial-less inverted L, but ones from several states away are equal or
better on the radial-less inverted L. Both seem to make good sense at this
point. I sure will be interested to see the effects of 4 and then 8 and on
up radials, but that is going to take a few days, because I don't want to
make radial changes unless I have access to low angle signals, which only
happens at night or just before sunrise.

Tomorrow is radial day. I will be laying out 4 radials 65' long to begin
with. I have resistance and reactance measurements every 50 khz as a
baseline, before installing radials. 4 in the early morning, 4 more just
before sunset, then 4 more the next morning, and the final 4 the next
evening. #14 THHN stranded insulated copper wire for the radials, btw.

Depending on what I end up seeing for "effect" I'll go to 24 or 32 radials
by winter....but only if the improvement is both measurable and "observable
on the air"...radials are a pain in the rear (or more accurately, the knees)
to put in.

What fun!

....hasan, N0AN

Starting point for the inverted L with sloping top loading wire.

45' high, 25.8' sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded. Mounted 7" above the earth, directly
to a 3' ground rod (strictly for mechanical support, as I had a prefab mount
with 3/8x24 on one end and SO-29 on the other)

Predicted Radiation Resistance (Devoldere): 25.8 ohms, very good ground
(rich pastoral, midwest).


I see I had confused feedpoint impedance and radiation resistance (after
reading some more in Devoldere's "Low-Band DX'ing")

According to Figure 9-94, the radiation resistance for my inverted L is
approximately 25 ohms. According to EZnec 4.1, source data says:

Impedance = 25.58 + J 1.872 ohms at 3600 khz.

When I measure the antenna with the MFJ-269, I get:

R=37 and X=0

If Devoldere and EZNEC are correct (although EZNEC may or may not be
measuring radiation resistance), then my radial-less inverted L is showing
ground losses of 37-25=12 ohms. If so, then my efficiency, without radials
is:
25/(25+12) or 25/37 or approximately 67%.

Before installing radials this morning, I just want to make sure I'm looking
at the right variables and interpreting them properly. 4 radials, laying on
the ground, will be ready to install when the sun comes up. 4 more later in
the day, etc., up to a total of 16 (the amount of wire I have ready to go).
Each time I put down 4, I'll take another measurement with the 269. For
kicks, I might take a measurement with just one or two first.

....hasan, N0AN

At what point in the system are you making your measurements?

hasan schiers wrote:

45' high, 25.8 sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded.

Predicted Radiation Resistance: 25.8 ohms, very good ground (rich pastoral,
midwest).

With no radials, I get a flat 50 ohm match at 3595 khz. Obviously this would
indicate ground losses of approximately 25 ohms, if I'm thinking about this
right. Also, predicted efficiency would then be 50 % (25/(25+25), indicating
a 3 dB loss. Forgetting about fresnel region losses, this seems to be better
than I had expected. 2:1 vswr bandwidth is very broad....broader than what I
get with EZnec 4.x with a 25 ohm load in the base.

This means one of two things to me:

Either my ground losses are much higher than the 25 ohms I'm indirectly
calculating, or I have made some sort of conceptual error in thinking about
what the implications are of a 25 or 26 ohm feedpoint. All my references
point toward a 25 ohm radiation resistance for my 42' vertical x 25.8 ft
inverted L (with sloping top wire instead of flat top wire). What is wrong
with my logic here? If the R(rad) is 25 ohms, and I measure a flat VSWR (on
two other meters) at 3600 khz, then isn't the remaining 25 ohms, ground
loss?

I also show about 37 ohms resistance and 0 ohms reactance at 3600 khz with
my MFJ-269, which is really confusing, in that if I have 25 ohms for Rrad,
then I have 13 ohms of ground losses. Further, 37 ohms is around 1.3 to 1.
So I have two other vswr meters showing 1:1 at 3600, and the MFJ showing 37
ohms. This is a pretty large percentage difference.

I would be inclined to believe the 25.8 ohms predicted by both EZnec 4 and
the Low Band DX'rs Handbook. In any case, I'll put out 4 radials tomorrow
morning and repeat all my measurements, looking for narrowing bandwidth and
lowered input Z as my ground losses decrease.

Ultimately, I'm going to put down 16, 66' radials, in steps of four, taking
measurements of input Z (mfj-269) and vswr bandwidth for 2:1, at 0,4,8 and
16 radials. I'll report what happens as I go along.

Anywho, without any radials at all there are quite a few distant signals on
80m this evening, that are consistently louder on the newly installed
inverted L, than on my Carolina Windom at 45'. Most signals as one pans the
band, are louder (at 2 hours after sunset) on the C. Windom than on the
radial-less inverted L, but ones from several states away are equal or
better on the radial-less inverted L. Both seem to make good sense at this
point. I sure will be interested to see the effects of 4 and then 8 and on
up radials, but that is going to take a few days, because I don't want to
make radial changes unless I have access to low angle signals, which only
happens at night or just before sunrise.

Tomorrow is radial day. I will be laying out 4 radials 65' long to begin
with. I have resistance and reactance measurements every 50 khz as a
baseline, before installing radials. 4 in the early morning, 4 more just
before sunset, then 4 more the next morning, and the final 4 the next
evening. #14 THHN stranded insulated copper wire for the radials, btw.

Depending on what I end up seeing for "effect" I'll go to 24 or 32 radials
by winter....but only if the improvement is both measurable and "observable
on the air"...radials are a pain in the rear (or more accurately, the knees)
to put in.

What fun!

...hasan, N0AN

Question: Where was I taking my measurements.

I started out at the actual feedpoint...then put in about 55' of LMR-400,
and started a new set of measurements in the shack. Here is the latest data:

Radials 2:1 Fo 2:1 BW Z VSWR @ Fo
0 3340 3522 3920 580 36,0 1.3
2 3354 3524 3774 420 45,0 1.0
4 3419 3533 3741 322 60,1 1.2
8 3445 3550 3742 297 65,4 1.3

The formatting is bad, but in order, left to right:

Number of Radials
Lower 2:1 vswr point
Resonant Freq point
Upper 2:1 point
Bandwidth in kilohertz
Impedance as shown on the MFJ 269 at resonance.

I'm a bit confused by the rising feedpoint impedance with increasing number
of radials. That seems backwards to me.

73,

....hasan, N0AN

VSWR shown by MFJ 269 at resonance
"Ham op" wrote in message
...
At what point in the system are you making your measurements?

hasan schiers wrote:

45' high, 25.8 sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded.

Predicted Radiation Resistance: 25.8 ohms, very good ground (rich
pastoral, midwest).

With no radials, I get a flat 50 ohm match at 3595 khz. Obviously this
would indicate ground losses of approximately 25 ohms, if I'm thinking
about this right. Also, predicted efficiency would then be 50 %
(25/(25+25), indicating a 3 dB loss. Forgetting about fresnel region
losses, this seems to be better than I had expected. 2:1 vswr bandwidth
is very broad....broader than what I get with EZnec 4.x with a 25 ohm
load in the base.

This means one of two things to me:

Either my ground losses are much higher than the 25 ohms I'm indirectly
calculating, or I have made some sort of conceptual error in thinking
about what the implications are of a 25 or 26 ohm feedpoint. All my
references point toward a 25 ohm radiation resistance for my 42' vertical
x 25.8 ft inverted L (with sloping top wire instead of flat top wire).
What is wrong with my logic here? If the R(rad) is 25 ohms, and I measure
a flat VSWR (on two other meters) at 3600 khz, then isn't the remaining
25 ohms, ground loss?

I also show about 37 ohms resistance and 0 ohms reactance at 3600 khz
with my MFJ-269, which is really confusing, in that if I have 25 ohms for
Rrad, then I have 13 ohms of ground losses. Further, 37 ohms is around
1.3 to 1. So I have two other vswr meters showing 1:1 at 3600, and the
MFJ showing 37 ohms. This is a pretty large percentage difference.

I would be inclined to believe the 25.8 ohms predicted by both EZnec 4
and the Low Band DX'rs Handbook. In any case, I'll put out 4 radials
tomorrow morning and repeat all my measurements, looking for narrowing
bandwidth and lowered input Z as my ground losses decrease.

Ultimately, I'm going to put down 16, 66' radials, in steps of four,
taking measurements of input Z (mfj-269) and vswr bandwidth for 2:1, at
0,4,8 and 16 radials. I'll report what happens as I go along.

Anywho, without any radials at all there are quite a few distant signals
on 80m this evening, that are consistently louder on the newly installed
inverted L, than on my Carolina Windom at 45'. Most signals as one pans
the band, are louder (at 2 hours after sunset) on the C. Windom than on
the radial-less inverted L, but ones from several states away are equal
or better on the radial-less inverted L. Both seem to make good sense at
this point. I sure will be interested to see the effects of 4 and then 8
and on up radials, but that is going to take a few days, because I don't
want to make radial changes unless I have access to low angle signals,
which only happens at night or just before sunrise.

Tomorrow is radial day. I will be laying out 4 radials 65' long to begin
with. I have resistance and reactance measurements every 50 khz as a
baseline, before installing radials. 4 in the early morning, 4 more just
before sunset, then 4 more the next morning, and the final 4 the next
evening. #14 THHN stranded insulated copper wire for the radials, btw.

Depending on what I end up seeing for "effect" I'll go to 24 or 32
radials by winter....but only if the improvement is both measurable and
"observable on the air"...radials are a pain in the rear (or more
accurately, the knees) to put in.

What fun!

...hasan, N0AN

OK, here is my summary table for up to 8 radials, 66 feet long, insulated
wire, laying on the ground: (all measurements at the shack end of 55' of
LMR-400 coax, buried)

Radials 2:1 Fo 2:1 BW Z VSWR @ Fo
0 3340 3522 3920 580 36,0 1.3
2 3354 3524 3774 420 45,0 1.0
4 3419 3533 3741 322 60,1 1.2
8 3445 3550 3742 297 65,4 1.3

The formatting is bad, but in order, left to right:

Number of Radials
Lower 2:1 vswr point
Resonant Freq point
Upper 2:1 point
Bandwidth in kilohertz
Impedance as shown on the MFJ 269 at resonance.

I'm a bit confused by the rising feedpoint impedance with increased radial
numbers, but the narrowing down of the bandwidth indicates decreased losses.
It also indicates (since it continues to decrease), that I should add
another 8 radials to see if I begin approaching the asymptote (sp?). The
rate of change is slowing quite a bit.

Any input as to explanations and the data are most welcome.

....hasan, N0AN

p.s. Performance seems quite good for a VERY limited sample. A w6 this
morning was 2 to 3 S-units stronger on the inverted L than on the 45' high
Carolina Windom 80. An LU6 was coming in S9 with an S5 noise level, and
responded with a 59+ signal report on the first call. A sampling of other
signals prior to or shortly after sunrise is showing a clear superiority of
the inverted L with 8 radials over the CW 80, at distances 1500 km. Less
than that distance and either antenna could have the upper hand until one
gets to within the state of Iowa. I'll have to do more measurements to get a
firm idea as to where the cross-over point is between the two antennas.
"hasan schiers" wrote in message
...
45' high, 25.8 sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded.

Predicted Radiation Resistance: 25.8 ohms, very good ground (rich
pastoral, midwest).

With no radials, I get a flat 50 ohm match at 3595 khz. Obviously this
would indicate ground losses of approximately 25 ohms, if I'm thinking
about this right. Also, predicted efficiency would then be 50 %
(25/(25+25), indicating a 3 dB loss. Forgetting about fresnel region
losses, this seems to be better than I had expected. 2:1 vswr bandwidth is
very broad....broader than what I get with EZnec 4.x with a 25 ohm load in
the base.

This means one of two things to me:

Either my ground losses are much higher than the 25 ohms I'm indirectly
calculating, or I have made some sort of conceptual error in thinking
about what the implications are of a 25 or 26 ohm feedpoint. All my
references point toward a 25 ohm radiation resistance for my 42' vertical
x 25.8 ft inverted L (with sloping top wire instead of flat top wire).
What is wrong with my logic here? If the R(rad) is 25 ohms, and I measure
a flat VSWR (on two other meters) at 3600 khz, then isn't the remaining 25
ohms, ground loss?

I also show about 37 ohms resistance and 0 ohms reactance at 3600 khz with
my MFJ-269, which is really confusing, in that if I have 25 ohms for Rrad,
then I have 13 ohms of ground losses. Further, 37 ohms is around 1.3 to 1.
So I have two other vswr meters showing 1:1 at 3600, and the MFJ showing
37 ohms. This is a pretty large percentage difference.

I would be inclined to believe the 25.8 ohms predicted by both EZnec 4 and
the Low Band DX'rs Handbook. In any case, I'll put out 4 radials tomorrow
morning and repeat all my measurements, looking for narrowing bandwidth
and lowered input Z as my ground losses decrease.

Ultimately, I'm going to put down 16, 66' radials, in steps of four,
taking measurements of input Z (mfj-269) and vswr bandwidth for 2:1, at
0,4,8 and 16 radials. I'll report what happens as I go along.

Anywho, without any radials at all there are quite a few distant signals
on 80m this evening, that are consistently louder on the newly installed
inverted L, than on my Carolina Windom at 45'. Most signals as one pans
the band, are louder (at 2 hours after sunset) on the C. Windom than on
the radial-less inverted L, but ones from several states away are equal or
better on the radial-less inverted L. Both seem to make good sense at
this point. I sure will be interested to see the effects of 4 and then 8
and on up radials, but that is going to take a few days, because I don't
want to make radial changes unless I have access to low angle signals,
which only happens at night or just before sunrise.

Tomorrow is radial day. I will be laying out 4 radials 65' long to begin
with. I have resistance and reactance measurements every 50 khz as a
baseline, before installing radials. 4 in the early morning, 4 more just
before sunset, then 4 more the next morning, and the final 4 the next
evening. #14 THHN stranded insulated copper wire for the radials, btw.

Depending on what I end up seeing for "effect" I'll go to 24 or 32 radials
by winter....but only if the improvement is both measurable and
"observable on the air"...radials are a pain in the rear (or more
accurately, the knees) to put in.

What fun!

...hasan, N0AN

On Fri, 2 Sep 2005 23:29:17 -0500, "hasan schiers"
wrote:

45' high, 25.8 sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded.

Predicted Radiation Resistance: 25.8 ohms, very good ground (rich pastoral,
midwest).

With no radials, I get a flat 50 ohm match at 3595 khz. Obviously this would
indicate ground losses of approximately 25 ohms, if I'm thinking about this
right. Also, predicted efficiency would then be 50 % (25/(25+25), indicating
a 3 dB loss. Forgetting about fresnel region losses, this seems to be better
than I had expected. 2:1 vswr bandwidth is very broad....broader than what I
get with EZnec 4.x with a 25 ohm load in the base.

This means one of two things to me:

Either my ground losses are much higher than the 25 ohms I'm indirectly
calculating, or I have made some sort of conceptual error in thinking about
what the implications are of a 25 or 26 ohm feedpoint. All my references
point toward a 25 ohm radiation resistance for my 42' vertical x 25.8 ft
inverted L (with sloping top wire instead of flat top wire). What is wrong
with my logic here? If the R(rad) is 25 ohms, and I measure a flat VSWR (on
two other meters) at 3600 khz, then isn't the remaining 25 ohms, ground
loss?

I also show about 37 ohms resistance and 0 ohms reactance at 3600 khz with
my MFJ-269, which is really confusing, in that if I have 25 ohms for Rrad,
then I have 13 ohms of ground losses. Further, 37 ohms is around 1.3 to 1.
So I have two other vswr meters showing 1:1 at 3600, and the MFJ showing 37
ohms. This is a pretty large percentage difference.

I would be inclined to believe the 25.8 ohms predicted by both EZnec 4 and
the Low Band DX'rs Handbook. In any case, I'll put out 4 radials tomorrow
morning and repeat all my measurements, looking for narrowing bandwidth and
lowered input Z as my ground losses decrease.

Ultimately, I'm going to put down 16, 66' radials, in steps of four, taking
measurements of input Z (mfj-269) and vswr bandwidth for 2:1, at 0,4,8 and
16 radials. I'll report what happens as I go along.

Anywho, without any radials at all there are quite a few distant signals on
80m this evening, that are consistently louder on the newly installed
inverted L, than on my Carolina Windom at 45'. Most signals as one pans the
band, are louder (at 2 hours after sunset) on the C. Windom than on the
radial-less inverted L, but ones from several states away are equal or
better on the radial-less inverted L. Both seem to make good sense at this
point. I sure will be interested to see the effects of 4 and then 8 and on
up radials, but that is going to take a few days, because I don't want to
make radial changes unless I have access to low angle signals, which only
happens at night or just before sunrise.

Tomorrow is radial day. I will be laying out 4 radials 65' long to begin
with. I have resistance and reactance measurements every 50 khz as a
baseline, before installing radials. 4 in the early morning, 4 more just
before sunset, then 4 more the next morning, and the final 4 the next
evening. #14 THHN stranded insulated copper wire for the radials, btw.

Depending on what I end up seeing for "effect" I'll go to 24 or 32 radials
by winter....but only if the improvement is both measurable and "observable
on the air"...radials are a pain in the rear (or more accurately, the knees)
to put in.

What fun!

Indeed.

Unfortunately, I believe that you are at the mercy of your
instrumentation. I doubt that you can make meaningful measurements of
the differences resulting from the addition of a few radials at a
time.

The fact that you can't get correlation between measurements made on
the -same- antenna with different instruments is a problem. Until you
have two clocks that read the same, you don't know what time it is.

I do have correlation now. The vswr meters and the mfj all read the same
resonant frequency now, Wes. See my post that shows the data for 0,2,4,8
radials. While a given absolute value might be in error (a certainty due to
inexpensive instruments), the trend is sound for bandwidth, but a bit
strange for feedpoint impedance. (BW is narrowing but input Z is going up,
with increasing numbers of radials.)

Ideas?

73,

....hasan, N0AN
"Wes Stewart" wrote in message
...
On Fri, 2 Sep 2005 23:29:17 -0500, "hasan schiers"
wrote:

45' high, 25.8 sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded.

Predicted Radiation Resistance: 25.8 ohms, very good ground (rich
pastoral,
midwest).

With no radials, I get a flat 50 ohm match at 3595 khz. Obviously this
would
indicate ground losses of approximately 25 ohms, if I'm thinking about
this
right. Also, predicted efficiency would then be 50 % (25/(25+25),
indicating
a 3 dB loss. Forgetting about fresnel region losses, this seems to be
better
than I had expected. 2:1 vswr bandwidth is very broad....broader than what
I
get with EZnec 4.x with a 25 ohm load in the base.

This means one of two things to me:

Either my ground losses are much higher than the 25 ohms I'm indirectly
calculating, or I have made some sort of conceptual error in thinking
about
what the implications are of a 25 or 26 ohm feedpoint. All my references
point toward a 25 ohm radiation resistance for my 42' vertical x 25.8 ft
inverted L (with sloping top wire instead of flat top wire). What is wrong
with my logic here? If the R(rad) is 25 ohms, and I measure a flat VSWR
(on
two other meters) at 3600 khz, then isn't the remaining 25 ohms, ground
loss?

I also show about 37 ohms resistance and 0 ohms reactance at 3600 khz with
my MFJ-269, which is really confusing, in that if I have 25 ohms for Rrad,
then I have 13 ohms of ground losses. Further, 37 ohms is around 1.3 to 1.
So I have two other vswr meters showing 1:1 at 3600, and the MFJ showing
37
ohms. This is a pretty large percentage difference.

I would be inclined to believe the 25.8 ohms predicted by both EZnec 4 and
the Low Band DX'rs Handbook. In any case, I'll put out 4 radials tomorrow
morning and repeat all my measurements, looking for narrowing bandwidth
and
lowered input Z as my ground losses decrease.

Ultimately, I'm going to put down 16, 66' radials, in steps of four,
taking
measurements of input Z (mfj-269) and vswr bandwidth for 2:1, at 0,4,8 and
16 radials. I'll report what happens as I go along.

Anywho, without any radials at all there are quite a few distant signals
on
80m this evening, that are consistently louder on the newly installed
inverted L, than on my Carolina Windom at 45'. Most signals as one pans
the
band, are louder (at 2 hours after sunset) on the C. Windom than on the
radial-less inverted L, but ones from several states away are equal or
better on the radial-less inverted L. Both seem to make good sense at
this
point. I sure will be interested to see the effects of 4 and then 8 and on
up radials, but that is going to take a few days, because I don't want to
make radial changes unless I have access to low angle signals, which only
happens at night or just before sunrise.

Tomorrow is radial day. I will be laying out 4 radials 65' long to begin
with. I have resistance and reactance measurements every 50 khz as a
baseline, before installing radials. 4 in the early morning, 4 more just
before sunset, then 4 more the next morning, and the final 4 the next
evening. #14 THHN stranded insulated copper wire for the radials, btw.

Depending on what I end up seeing for "effect" I'll go to 24 or 32 radials
by winter....but only if the improvement is both measurable and
"observable
on the air"...radials are a pain in the rear (or more accurately, the
knees)
to put in.

What fun!

Indeed.

Unfortunately, I believe that you are at the mercy of your
instrumentation. I doubt that you can make meaningful measurements of
the differences resulting from the addition of a few radials at a
time.

The fact that you can't get correlation between measurements made on
the -same- antenna with different instruments is a problem. Until you
have two clocks that read the same, you don't know what time it is.

If your antenna is over a PERFECT ground, an EM mirror, then the
mutually coupled impedance between the antenna and it's image antenna
gets to be a bit difficult to calculate or estimate. The Apex and it's
image are 80 feet apart. That is 107 degree spacing, and the ends are 77
degrees apart. The mutual impedance along the length of the antenna
changes due to the difference in phase shift.

Change from perfect reflecting ground to 'real' ground with varying
conductivity and permittivity as a function of length, width and depth
and the problem becomes much more complicated.

Your measurements, in your location, with your installation indicate, to
me, that your 8 radial solution is starting to converge to best
solution. I say this for two reasons. Your 2:1 VSWR bandwidth is narrow
and your Z is approaching 73 ohms.

I would use the eight radial solution and trim the antenna length to
your desired center frequency. Remember, a 2:1 VSWR indicates that 90%
of your energy is going into the antenna.

For the best analysis of your installation, the soil characteristics
would have to be known and controlled for several wavelengths square and
approximately 1/4 wavelength deep. Your radials [counterpoise] are
simplifying and stabilizing your solution.

Roy Llewellen is much better qualified than I to proceed deeper into the
EM Physics regarding all the possible interactions. If the science of
what's happening is your interest then contact Roy off-line [Roy, sorry
to volunteer you without your consent]. If a brief understanding of
possible contributing EM effects is your desire, then I hope this
contributes to your understanding.

Ham Op

hasan schiers wrote:

Question: Where was I taking my measurements.

I started out at the actual feedpoint...then put in about 55' of LMR-400,
and started a new set of measurements in the shack. Here is the latest data:

Radials 2:1 Fo 2:1 BW Z VSWR @ Fo
0 3340 3522 3920 580 36,0 1.3
2 3354 3524 3774 420 45,0 1.0
4 3419 3533 3741 322 60,1 1.2
8 3445 3550 3742 297 65,4 1.3

The formatting is bad, but in order, left to right:

Number of Radials
Lower 2:1 vswr point
Resonant Freq point
Upper 2:1 point
Bandwidth in kilohertz
Impedance as shown on the MFJ 269 at resonance.

I'm a bit confused by the rising feedpoint impedance with increasing number
of radials. That seems backwards to me.

73,

...hasan, N0AN

VSWR shown by MFJ 269 at resonance
"Ham op" wrote in message
...

At what point in the system are you making your measurements?

hasan schiers wrote:


45' high, 25.8 sloping wire at the top, 29 feet high at the far end. #12
THHN Insulated copper wire, stranded.

Predicted Radiation Resistance: 25.8 ohms, very good ground (rich
pastoral, midwest).

With no radials, I get a flat 50 ohm match at 3595 khz. Obviously this
would indicate ground losses of approximately 25 ohms, if I'm thinking
about this right. Also, predicted efficiency would then be 50 %
(25/(25+25), indicating a 3 dB loss. Forgetting about fresnel region
losses, this seems to be better than I had expected. 2:1 vswr bandwidth
is very broad....broader than what I get with EZnec 4.x with a 25 ohm
load in the base.

This means one of two things to me:

Either my ground losses are much higher than the 25 ohms I'm indirectly
calculating, or I have made some sort of conceptual error in thinking
about what the implications are of a 25 or 26 ohm feedpoint. All my
references point toward a 25 ohm radiation resistance for my 42' vertical
x 25.8 ft inverted L (with sloping top wire instead of flat top wire).
What is wrong with my logic here? If the R(rad) is 25 ohms, and I measure
a flat VSWR (on two other meters) at 3600 khz, then isn't the remaining
25 ohms, ground loss?

I also show about 37 ohms resistance and 0 ohms reactance at 3600 khz
with my MFJ-269, which is really confusing, in that if I have 25 ohms for
Rrad, then I have 13 ohms of ground losses. Further, 37 ohms is around
1.3 to 1. So I have two other vswr meters showing 1:1 at 3600, and the
MFJ showing 37 ohms. This is a pretty large percentage difference.

I would be inclined to believe the 25.8 ohms predicted by both EZnec 4
and the Low Band DX'rs Handbook. In any case, I'll put out 4 radials
tomorrow morning and repeat all my measurements, looking for narrowing
bandwidth and lowered input Z as my ground losses decrease.

Ultimately, I'm going to put down 16, 66' radials, in steps of four,
taking measurements of input Z (mfj-269) and vswr bandwidth for 2:1, at
0,4,8 and 16 radials. I'll report what happens as I go along.

Anywho, without any radials at all there are quite a few distant signals
on 80m this evening, that are consistently louder on the newly installed
inverted L, than on my Carolina Windom at 45'. Most signals as one pans
the band, are louder (at 2 hours after sunset) on the C. Windom than on
the radial-less inverted L, but ones from several states away are equal
or better on the radial-less inverted L. Both seem to make good sense at
this point. I sure will be interested to see the effects of 4 and then 8
and on up radials, but that is going to take a few days, because I don't
want to make radial changes unless I have access to low angle signals,
which only happens at night or just before sunrise.

Tomorrow is radial day. I will be laying out 4 radials 65' long to begin
with. I have resistance and reactance measurements every 50 khz as a
baseline, before installing radials. 4 in the early morning, 4 more just
before sunset, then 4 more the next morning, and the final 4 the next
evening. #14 THHN stranded insulated copper wire for the radials, btw.

Depending on what I end up seeing for "effect" I'll go to 24 or 32
radials by winter....but only if the improvement is both measurable and
"observable on the air"...radials are a pain in the rear (or more
accurately, the knees) to put in.

What fun!

...hasan, N0AN

I'm a bit confused by the rising feedpoint impedance with increasing
number
of radials. That seems backwards to me.

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

SWR increases the further the impedance, either HIGHER or LOWER,
departs from 50 ohms.

The only way to measure antenna input impedance is by means of an
impedance bridge. Try one of the small antenna analysers.
----
Reg.

That is exactly what I'm using Reg, and why I"m puzzled. I'm getting rising
feedpoint impedance with increasing numbers of radials. The 2:1 bandwidth is
getting narrower, as it should, but what accounts for the increasing
feedpoint impedance? MFJ-269 antenna analyzer is what generated the table I
posted earlier.

Very strange?

....hasan, N0AN
"Reg Edwards" wrote in message
...
I'm a bit confused by the rising feedpoint impedance with increasing
number
of radials. That seems backwards to me.

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

SWR increases the further the impedance, either HIGHER or LOWER,
departs from 50 ohms.

The only way to measure antenna input impedance is by means of an
impedance bridge. Try one of the small antenna analysers.
----
Reg.