"John S" wrote in message ...

On 6/29/2015 10:48 AM, Wayne wrote:
As a lead in, I use a 16 ft vertical on 20-10 meters, mounted on a flat
metal roof. The antenna is fed with about 25 feet of RG-8, and there is
a tuner at the transmit end.

While I'm pretty happy with the antenna, I'd like to simplify the
matching.

Thus, the question: what is the purpose of a 1:4 unun on a 43 foot
vertical? ( I assume the "4" side is on the antenna side.)

I'd expect a better coax to antenna match when the antenna feedpoint is
a high Z (example, at 30 meters), but I'd also expect a worse coax to
antenna match when the feedpoint is a low Z (example, at 10 meters).

Is that the way it works, or is there other magic involved?

I think we strayed off the path to answering your original question.

The short answer is that you are correct and there is no magic involved. A
bit longer answer is:

A 43ft vertical will present a feed impedance of 1010 + J 269.2 ohms at 30
meters. Using a 1:4 transformer at the feed point will reduce that to 253 +
J 67 ohms. That is a bit closer to your 50 ohm line.

At 10 meters, the antenna will present a 147 + J 133 ohms impedance. A 1:4
transformer will reduce that to 37 + J 33 ohms.

There are several disclaimers I could include, but I think you understand
that the answers cannot be exact with the info presented.

I hope this helps.

Thanks John.
Yes, we have strayed from the original question, but I have found the
discussion stimulating.
Perhaps a new thread should be started to address those subjects.

If I use EZNEC to model the 43 footer over perfect ground with a 3 inch
diameter radiator, I get impedances in the same ball park as you list.

If I change the "alt SWR Z0" to 200 ohms (presumably what the antenna would
see as a feedline, if a 4:1 unun had 50 ohm coax on the other side), the SWR
plot becomes interesting.

The plot has SWRs of about 2.5:1 to 5:1 over most of the range, with SWR
getting below 2.5:1 around 29 MHz.

Is that a valid approach?

On 7/3/2015 10:37 AM, Wayne wrote:


"John S" wrote in message ...

On 6/29/2015 10:48 AM, Wayne wrote:
As a lead in, I use a 16 ft vertical on 20-10 meters, mounted on a flat
metal roof. The antenna is fed with about 25 feet of RG-8, and there is
a tuner at the transmit end.

While I'm pretty happy with the antenna, I'd like to simplify the
matching.

Thus, the question: what is the purpose of a 1:4 unun on a 43 foot
vertical? ( I assume the "4" side is on the antenna side.)

I'd expect a better coax to antenna match when the antenna feedpoint is
a high Z (example, at 30 meters), but I'd also expect a worse coax to
antenna match when the feedpoint is a low Z (example, at 10 meters).

Is that the way it works, or is there other magic involved?

I think we strayed off the path to answering your original question.

The short answer is that you are correct and there is no magic
involved. A bit longer answer is:

A 43ft vertical will present a feed impedance of 1010 + J 269.2 ohms
at 30 meters. Using a 1:4 transformer at the feed point will reduce
that to 253 + J 67 ohms. That is a bit closer to your 50 ohm line.

At 10 meters, the antenna will present a 147 + J 133 ohms impedance. A
1:4 transformer will reduce that to 37 + J 33 ohms.

There are several disclaimers I could include, but I think you
understand that the answers cannot be exact with the info presented.

I hope this helps.

Thanks John.
Yes, we have strayed from the original question, but I have found the
discussion stimulating.
Perhaps a new thread should be started to address those subjects.

If I use EZNEC to model the 43 footer over perfect ground with a 3 inch
diameter radiator, I get impedances in the same ball park as you list.

If I change the "alt SWR Z0" to 200 ohms (presumably what the antenna
would see as a feedline, if a 4:1 unun had 50 ohm coax on the other
side), the SWR plot becomes interesting.

The plot has SWRs of about 2.5:1 to 5:1 over most of the range, with SWR
getting below 2.5:1 around 29 MHz.

Is that a valid approach?

I have not done what you have done, but it sounds correct. I'll try to
verify what you have done when time permits.

I really think you know what you are doing. Don't forget that EZNEC can
use transmission lines, transformers, inductors, capacitors, resistors
and other stuff to help in your analysis. Although the true answers come
from the physical implementation, it is very helpful to use EZNEC to
gain insight into the situation. And, I think you know that as well.

On 7/3/2015 10:37 AM, Wayne wrote:


"John S" wrote in message ...

On 6/29/2015 10:48 AM, Wayne wrote:
As a lead in, I use a 16 ft vertical on 20-10 meters, mounted on a flat
metal roof. The antenna is fed with about 25 feet of RG-8, and there is
a tuner at the transmit end.

While I'm pretty happy with the antenna, I'd like to simplify the
matching.

Thus, the question: what is the purpose of a 1:4 unun on a 43 foot
vertical? ( I assume the "4" side is on the antenna side.)

I'd expect a better coax to antenna match when the antenna feedpoint is
a high Z (example, at 30 meters), but I'd also expect a worse coax to
antenna match when the feedpoint is a low Z (example, at 10 meters).

Is that the way it works, or is there other magic involved?

I think we strayed off the path to answering your original question.

The short answer is that you are correct and there is no magic
involved. A bit longer answer is:

A 43ft vertical will present a feed impedance of 1010 + J 269.2 ohms
at 30 meters. Using a 1:4 transformer at the feed point will reduce
that to 253 + J 67 ohms. That is a bit closer to your 50 ohm line.

At 10 meters, the antenna will present a 147 + J 133 ohms impedance. A
1:4 transformer will reduce that to 37 + J 33 ohms.

There are several disclaimers I could include, but I think you
understand that the answers cannot be exact with the info presented.

I hope this helps.

Thanks John.
Yes, we have strayed from the original question, but I have found the
discussion stimulating.


Indeed! So have I.


Perhaps a new thread should be started to address those subjects.


Please start one if you feel compelled.


If I use EZNEC to model the 43 footer over perfect ground with a 3 inch
diameter radiator, I get impedances in the same ball park as you list.


Ha! I used 1.5 inches. I will re-do.


If I change the "alt SWR Z0" to 200 ohms (presumably what the antenna
would see as a feedline, if a 4:1 unun had 50 ohm coax on the other
side), the SWR plot becomes interesting.


I've never done that. I will explore this set-up.


The plot has SWRs of about 2.5:1 to 5:1 over most of the range, with SWR
getting below 2.5:1 around 29 MHz.

Are we still considering a 10MHz to 30Mhz frequency sweep?

Is that a valid approach?

You might be ahead of me on this.

"John S" wrote in message ...

On 7/3/2015 10:37 AM, Wayne wrote:


"John S" wrote in message ...

On 6/29/2015 10:48 AM, Wayne wrote:
As a lead in, I use a 16 ft vertical on 20-10 meters, mounted on a flat
metal roof. The antenna is fed with about 25 feet of RG-8, and there is
a tuner at the transmit end.

While I'm pretty happy with the antenna, I'd like to simplify the
matching.

Thus, the question: what is the purpose of a 1:4 unun on a 43 foot
vertical? ( I assume the "4" side is on the antenna side.)

I'd expect a better coax to antenna match when the antenna feedpoint is
a high Z (example, at 30 meters), but I'd also expect a worse coax to
antenna match when the feedpoint is a low Z (example, at 10 meters).

Is that the way it works, or is there other magic involved?

I think we strayed off the path to answering your original question.

The short answer is that you are correct and there is no magic
involved. A bit longer answer is:

A 43ft vertical will present a feed impedance of 1010 + J 269.2 ohms
at 30 meters. Using a 1:4 transformer at the feed point will reduce
that to 253 + J 67 ohms. That is a bit closer to your 50 ohm line.

At 10 meters, the antenna will present a 147 + J 133 ohms impedance. A
1:4 transformer will reduce that to 37 + J 33 ohms.

There are several disclaimers I could include, but I think you
understand that the answers cannot be exact with the info presented.

I hope this helps.

Thanks John.
Yes, we have strayed from the original question, but I have found the
discussion stimulating.


Indeed! So have I.


Perhaps a new thread should be started to address those subjects.


Please start one if you feel compelled.


If I use EZNEC to model the 43 footer over perfect ground with a 3 inch
diameter radiator, I get impedances in the same ball park as you list.


Ha! I used 1.5 inches. I will re-do.


If I change the "alt SWR Z0" to 200 ohms (presumably what the antenna
would see as a feedline, if a 4:1 unun had 50 ohm coax on the other
side), the SWR plot becomes interesting.


I've never done that. I will explore this set-up.


The plot has SWRs of about 2.5:1 to 5:1 over most of the range, with SWR
getting below 2.5:1 around 29 MHz.

Are we still considering a 10MHz to 30Mhz frequency sweep?

Well, I have been running the SWR across 4 to 30 MHz, but mainly looking at
10 MHz and above.

As for EZNEC and transmission lines, I have never done that, but plan to
when I can. I don't follow how to do it. In the few cases I wanted the
info for a single frequency, I just used a Smith chart.

This thread has given me a lot to consider in improving my whip setup, but
details of the possibilities would run the thread off in the weeds

Okay. This data set is for a 43' carbon steel antenna on a perfect
ground fed with 25' of RG8A/U. No transformer.

Freq R X SWR

4.000 2.52 -12.74 21.140
5.000 20.16 20.82 2.977
6.000 28.78 -30.81 2.586
7.000 8.04 -5.76 6.307
8.000 5.68 12.25 9.337
9.000 6.08 30.66 11.344
10.000 8.95 56.02 12.703
11.000 20.21 104.84 13.685
12.000 137.06 277.80 14.297
13.000 126.21 -267.32 14.174
14.000 19.15 -95.40 12.417
15.000 11.09 -43.81 8.067
16.000 17.90 -11.07 2.949
17.000 56.99 -15.98 1.384
18.000 20.29 -31.49 3.568
19.000 9.29 -12.21 5.711
20.000 6.95 3.56 7.236
21.000 6.99 19.13 8.217
22.000 9.03 38.15 8.829
23.000 15.83 67.71 9.161
24.000 48.70 132.94 9.150
25.000 418.45 49.46 8.488
26.000 60.45 -119.25 6.589
27.000 28.69 -45.41 3.465
28.000 46.51 -9.99 1.245
29.000 62.03 -48.79 2.397
30.000 21.38 -41.26 4.116


This data set is the same except with a 1:4 transformer at the antenna.

Freq R X SWR
4.000 4.07 19.59 14.187
5.000 25.57 74.28 6.633
6.000 153.39 -83.56 4.058
7.000 25.51 -38.52 3.333
8.000 15.35 -6.11 3.312
9.000 16.11 18.43 3.567
10.000 26.59 49.05 3.970
11.000 87.00 102.27 4.497
12.000 180.75 -114.05 5.136
13.000 28.87 -72.84 5.814
14.000 11.18 -31.02 6.256
15.000 8.52 -4.23 5.914
16.000 13.30 23.05 4.607
17.000 50.10 61.48 3.196
18.000 107.24 -32.07 2.383
19.000 36.37 -30.20 2.135
20.000 22.85 -5.54 2.222
21.000 22.77 16.08 2.474
22.000 33.85 41.69 2.827
23.000 85.10 73.92 3.268
24.000 165.89 -60.03 3.790
25.000 39.38 -70.12 4.323
26.000 15.47 -31.46 4.605
27.000 12.03 -4.86 4.197
28.000 18.81 20.71 3.175
29.000 54.98 43.57 2.257
30.000 85.50 -14.78 1.786

Is this of any help?

On 7/4/2015 1:34 AM, John S wrote:
Okay. This data set is for a 43' carbon steel antenna on a perfect
ground fed with 25' of RG8A/U. No transformer.

I made a mistake. I used 3" copper pipe. I will re-do with 3" carbon
steel pipe.

No transformer:
Freq R X SWR
4.000 2.61 -12.68 20.382
5.000 20.92 20.65 2.867
6.000 28.18 -30.18 2.600
7.000 8.03 -5.57 6.304
8.000 5.70 12.35 9.317
9.000 6.11 30.75 11.314
10.000 9.00 56.13 12.662
11.000 20.37 105.05 13.626
12.000 139.02 278.20 14.204
13.000 125.69 -265.07 14.021
14.000 19.40 -94.97 12.182
15.000 11.41 -43.56 7.809
16.000 18.65 -11.02 2.830
17.000 56.19 -17.88 1.426
18.000 19.92 -31.06 3.599
19.000 9.26 -12.02 5.720
20.000 6.96 3.68 7.228
21.000 7.02 19.23 8.195
22.000 9.09 38.27 8.792
23.000 15.99 67.89 9.102
24.000 49.53 133.22 9.057
25.000 412.93 41.45 8.343
26.000 60.97 -117.33 6.399
27.000 29.70 -44.72 3.324
28.000 48.31 -10.74 1.247
29.000 60.26 -49.68 2.445
30.000 21.05 -40.86 4.142

1:4 transformer:
Freq R X SWR
4.000 4.21 19.69 13.745
5.000 26.48 74.45 6.450
6.000 149.09 -82.20 3.972
7.000 25.55 -37.90 3.288
8.000 15.45 -5.81 3.285
9.000 16.25 18.68 3.549
10.000 26.91 49.36 3.954
11.000 88.45 102.31 4.478
12.000 177.47 -114.21 5.105
13.000 28.81 -72.20 5.756
14.000 11.31 -30.71 6.152
15.000 8.73 -3.99 5.767
16.000 13.78 23.29 4.469
17.000 51.75 60.81 3.109
18.000 104.23 -32.25 2.336
19.000 36.12 -29.39 2.111
20.000 22.93 -5.09 2.210
21.000 22.96 16.44 2.467
22.000 34.32 42.05 2.819
23.000 86.65 73.65 3.255
24.000 162.78 -61.65 3.764
25.000 39.08 -69.10 4.270
26.000 15.65 -30.95 4.510
27.000 12.38 -4.51 4.075
28.000 19.52 20.93 3.075
29.000 56.33 42.38 2.197
30.000 83.40 -15.44 1.755

"John S" wrote in message ...

On 7/4/2015 1:34 AM, John S wrote:
Okay. This data set is for a 43' carbon steel antenna on a perfect
ground fed with 25' of RG8A/U. No transformer.

I made a mistake. I used 3" copper pipe. I will re-do with 3" carbon
steel pipe.

No transformer:
Freq R X SWR
4.000 2.61 -12.68 20.382
5.000 20.92 20.65 2.867
6.000 28.18 -30.18 2.600
7.000 8.03 -5.57 6.304
8.000 5.70 12.35 9.317
9.000 6.11 30.75 11.314
10.000 9.00 56.13 12.662
11.000 20.37 105.05 13.626
12.000 139.02 278.20 14.204
13.000 125.69 -265.07 14.021
14.000 19.40 -94.97 12.182
15.000 11.41 -43.56 7.809
16.000 18.65 -11.02 2.830
17.000 56.19 -17.88 1.426
18.000 19.92 -31.06 3.599
19.000 9.26 -12.02 5.720
20.000 6.96 3.68 7.228
21.000 7.02 19.23 8.195
22.000 9.09 38.27 8.792
23.000 15.99 67.89 9.102
24.000 49.53 133.22 9.057
25.000 412.93 41.45 8.343
26.000 60.97 -117.33 6.399
27.000 29.70 -44.72 3.324
28.000 48.31 -10.74 1.247
29.000 60.26 -49.68 2.445
30.000 21.05 -40.86 4.142

1:4 transformer:
Freq R X SWR
4.000 4.21 19.69 13.745
5.000 26.48 74.45 6.450
6.000 149.09 -82.20 3.972
7.000 25.55 -37.90 3.288
8.000 15.45 -5.81 3.285
9.000 16.25 18.68 3.549
10.000 26.91 49.36 3.954
11.000 88.45 102.31 4.478
12.000 177.47 -114.21 5.105
13.000 28.81 -72.20 5.756
14.000 11.31 -30.71 6.152
15.000 8.73 -3.99 5.767
16.000 13.78 23.29 4.469
17.000 51.75 60.81 3.109
18.000 104.23 -32.25 2.336
19.000 36.12 -29.39 2.111
20.000 22.93 -5.09 2.210
21.000 22.96 16.44 2.467
22.000 34.32 42.05 2.819
23.000 86.65 73.65 3.255
24.000 162.78 -61.65 3.764
25.000 39.08 -69.10 4.270
26.000 15.65 -30.95 4.510
27.000 12.38 -4.51 4.075
28.000 19.52 20.93 3.075
29.000 56.33 42.38 2.197
30.000 83.40 -15.44 1.755

Yes, very interesting. Throw in 75 feet of cable, and things get "better".

The lowest SWR is about 2:1 at 19 MHz.
It is about 6:1 on 20 meters.

On 7/4/2015 10:55 AM, Wayne wrote:


Yes, very interesting. Throw in 75 feet of cable, and things get "better".

The lowest SWR is about 2:1 at 19 MHz.
It is about 6:1 on 20 meters.



Of course. More loss in the cable makes it "better" (but, you know that).

On 7/4/2015 10:55 AM, Wayne wrote:


By the way, Wayne...

Are you aware of a companion Excel application for EZNEC called AutoEZ?
You can run many test cases in a few seconds using it. You can find it
on the EZNEC site.

It is how I generated the data I posted.

On 7/3/2015 1:06 PM, Wayne wrote:


As for EZNEC and transmission lines, I have never done that, but plan to
when I can. I don't follow how to do it.

Put a short piece of wire somewhere away from the antenna. Move your
source to this short piece of wire. Connect your transmission line
between the short wire and the antenna where you previously had the
source. Put the required line info into the transmission line box(es).
Start with a velocity factor of 1 and an attenuation of 0dB. You should
get the same results as before you moved your source. Then you can
adjust the Vf and loss based on the characteristics of the line that you
can find on line.

Cheers
John N1JLS