Cylinder dipoles on 10 meter

The cylinder dipole can be used as an indoor HF antenna, with VHF/UHF dimensions. Our test showed that the cylinder dipole constructed from aluminium energy drink cans can be used as a multi-band antenna on 10 m to 15 m.

In the weekend of the ARRL 10 meter contest, Alex SA5BFZ and I (PA1B) made CW QSO's on 10 meter both with our indoor cylinder dipoles.

Alex

Cylinder dipole of Alex SA5BFZ

Alex operated on Sunday, outside of the contest. He made 2 excellent QSO's from Sweden with Spain on 10 meter and a QSO with Russia on 17 m. Alex used the cylinder dipole that consists of two  500 ml energy drink cans and a coil of 80 mm with 8 or 9 turns. The photo shows the cylinder dipole of Alex.

Bert
I participated on Saturday and Sunday for two very short periods in the ARRL 10 meter contest. I was curious what my  Red Bull  antenna  would do on 10 meters. I never had the opportunity, to use it before on 10 m, due to the lack of propagation on 10 meters.

Coil and cans.     PA1B
The Cylinder Dipole principle
is not yet in the text book

I worked 2 stations on both days, within 8 minutes and within 5 minutes. With only 10 meter to operate, I was fully depending on the propagation on this band. My cylinder dipole with Red Bull cans is doing fine.
The signals must be S8 or stronger, then it is easy to make a QSO. In 3 QSO's I used 2.7 W. In the QSO with RU6AV I used just 0.8 W.
I used a cylinder dipole with two  Red Bull cans  and a coil of 40 mm with 14 turns.

Results
Both cylinder dipoles of Alex and me are doing fine on 10 meters. We made QSO's over large distances within Europe, with low power. The table below shows both call signs of our QRP stations and the stations that we worked, the distance in Miles and the used power in watt.

Lowest possible power
We both operated with the lowest possible power.  We reduce our power according the reading of the S-meter before we answer a CQ. To use the lowest possible power we must use S&P.

How to compare
Because we both used the lowest possible power, it is possible to compare the QSO's.
The QSO's can be compared by calculating the value of the Miles/quare root of the power or by calculating the Electrical field strength at the receive antenna.

deciBel

In the last column I compare the QSO's in dB. The higher the value in dB, the stronger the signal.
I choose my QSO with RN3GQ to be 0 dB. The other QSO's on 10 m are made under better conditions.
The value in dB shows the influences of the propagation and the antenna of the other station.

The higher the value in dB, the stronger the signal.

I say Thanks to URQRP.org for the link from their interesting site to this Blog entry.

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Miles per WHAT?

The calculation of Miles per Watt can not be used to compare QSO's. To double the distance we need more power. The power must be increased 4x to get the same signal strength.
The value  Miles/SQRT(watt) is calculated from the distance in miles divide by the square root of the power in watt. This value is very easy to calculate and is an excellent propagation indicator.
The higher this value, the better the propagation. (The value is NOT accurate over a short distance.)

Electrical field strength in V/m

.

E = electrical field strength  in  V/m
P = used power in watt.    
R = distance between the radio stations in meter.

An other way to compare is to calculate the Electrical field strength E.

The lower the Field strength the less power is needed to cover the distance, the better is the propagation.

WSPR Propagation Analysis - G3XBM 28 MHz Dec 2014 (2)

The propagation changes from day to day, as you can read in the blog of Roger G3XBM.

Here is an analysis of the WSPR spots of G3XBM that were received by K9AN 
on the 24th and the 28th of December 2014.  
The time is given in UTC.

The diagrams show a lot of spots, since K9AN listens every two minutes. hi

The lower the calculated lowest possible power, the better the propagation.

On the 24th, the propagation is at it's best around 13:50 UTC and 17:06 UTC,
with a calculated lowest possible power of 5 milliwatts.

 Click to enlarge.     G3XBM  received by  K9AN  on  2014-12-24

On the 28th the propagation has a short peak at 14:52 UTC.

Around that time there are seven successive spots, every two minutes.

In the spot of 16:36 utc, the full power of 500 mW is needed, to be spot. hi. 

G3XBM received by K9AN  on   2014-12-28

In most of the spots, the calculated lowest possible power is 50 mW or less, on both days.

This means that, if you would use CW instead of WSPR, that 1 watt (20 * 50 mW) could be used to make QSO's in CW.

WSPR Propagation Analysis - G3XBM 28 MHz Dec 2014

Roger G3XBM ran his WSPR signal for several days on 28 MHz.
This provides interesting information on propagation on 28 MHz.
I collected data from the WSPR database, to make the diagrams.

The first two diagrams, show spots that are collected over several days.
The strongest spots are given in red. 

The first two diagrams show the calculated electrical field strength in micro volt per meter.
If spots show the same field strength, the voltage on the antenna will be the same, for a simple wire antenna.
The difference between the successive values of the field strength is 5 dB.
This is about one S-point, since 6 dB is one S-point. 
The lower the value, the better the propagation.
So 0.03 micro volt/meter is about 1 S-point stronger than 0.06 micro volt/meter.

The strongest spot over 900 km was 2 S-points down, compared to the spot over 5300 km

The strongest (in red) spots show the same field strength.

Notice that the spots over 5300, 6500 and 14700 km were made with the same field strength at the receiving antenna, so the strength of the signal that arrived on the antenna  was the same in these three spots.

Further analysis shows which receiving stations have Excellent Ears. See the spots in red.
The spots in red in the table below correspond to the spots in red in the tables above.

The stations with excellent ears.

Power in CW
I was wondering, how much power would be needed to make  CW QSO's.
For a CW QSO you need  twenty times more power,  (Click) than for a WSPR spot. (13 dB)
The diagram below shows the  Calculated lowest possible power  (Click)in milliwatt for each spot.

For the strongest WSPR signal, received by K9AN the calculated lowest possible power is 2 mW.
Thsi means that the that 2 mW would be received with a SNR of -29 dB. (Solid copy in WSPR)
To be received in CW, a power of 20 * 2 = 40 mW would be needed.
This does not surprise me a bit, since I made a CW contest QSO with K3WW on 21 MHz in 2012 with 36 mW.

Rogers signal was also heard in VK. The calculated lowest possible power was 5 mW.
So in CW his signal would be heard with 20 * 5 = 100 mW.
This seem too low, but please notice that to double the distance it takes an increase of 1 S-point (6 dB) to get the same field strength.
One  S-point means four times more power.
Further, please notice that WSPR is patient and tireless.
It is even possible that one of the operators was a sleep during the time that the spot was made. hi.

10m WSPR - 5 watts from M0DEV

Mark M0DEV uses WSPR with 5 watts.

Today he made more than 400 spots on 10 m.

I noticed this since Mark left a note on the Blog of Roger G3XBM.

Mark notes:

Interesting. I am running 5 W (it's as low as my rig will go) and our two 3 hourly plots on wspr are all but identical. Neither of us has made any headway with the west side of the states.
The conclusion I draw is that when the band is open, it's open, and when it is shut it is shut: 

there is no point trying to blast it open with QRO.

The analysis below shows the calculated lowest possible power.

The lowest possible power is calculated from the power sent and the SNR.

The better the SNR, the lower the lowest possible power, the better the propagation.

The analysis shows that the propagation was good this day and confirms Marks statement that QRO is not needed.
Please notice that even with 100 mW, Marks signal would be heard over a large distance.

WSPR Propagation Analysis - G3XBM 28 MHz

Many WSPR operators jump from one band to the next, when band conditions changes.
Roger G3XBM ran his WSPR signal for several days on 28 MHz.
This provides interesting information on propagation on 28 MHz.
I collected data from the WSPR database, to make this diagram.

In this diagram, I choose to show the spots of Roger received by DK6UG over 600 kilometer and LB9YE over 1500 km.
The diagram shows the number of spots for a day and from hour to hour.
The stronger the signal, the lower the calculated lowest possible power.

DK6UG over 600 km
It's interesting to see that the propagation to DK6UG changes from day to day.
On the 13th there are two peaks in the propagation, with no propagation in between.
On the 14th there is only a spot on 18 UTC.
This is at the same time of the peak of the day before.
On the 15th there are 3 peaks at 11, 14 and 19 UTC
The 17th is the most interesting day.
The day starts with reception on 11 till 12:58 UTC.
The 17th shows one very strong spot at 14:10 UTC with a calculated lowest possible power of 10 mW. The next spot with a CLPP of 1000 mW was on 14:54 UTC. Notice that in this spot the signal strenght is 20 dB lower.
Please notice that there is no reception from 13:00 till 13:58 UTC on all days,except for the 19th.

LB9YE over 1500 km versus DK6UG over 600 km
Most interesting are 13th and 14th
At the 13th the propagation is good to DK6UG, but not to LB9YE.
At the 14th it's the other way around.

"WSPR Propagation Analysis" for WSPR spots of G3XBM on 10 m

Roger, G3XBM wrote:
Nothing at all was seen until mid-afternoon and then the band just opened wide!  
K9AN (6505km) last spotted my 2W signal at 2308z, which is after midnight local time and HOURS after the band has normally died out. It had been dark for hours. One wonders if this was F2 or even multi-hop Es? I wonder what was happening on 6m transatlantic?  I must check.
(Spots made on 2014-04-08) Click to visit the article.

I was interested, so I made an WSPR Propagation Analysis of the spots on that day and the days before. The second table shows the last spot at 23:08 UTC, but also reveals the rapid change in propagation around 22:20 UTC.

How to read the table 
In the analysis above, I show the "Calculated Lowest possible Power" in milliwatt and the hours of the day in UTC. The lower the "Calculated Lowest Possible Power", the better the propagation.

To compare the propagation over several days, 

I included 2014-03-28 till 2014-04-08.


Roger is refering to WSPR spots made on 2014-04-08.
At the bottom of the table above.
From 10 UTC to 22 UTC the propagation gets better.
The best propagation occurred in the spot with the red star made on 22:20 UTC.



Even more spectacular
The best propagation on 2014-03-28, at the top of the table, occurred between 13:00 and 15:59 UTC in the aftenoon.
But even more spectacular is the change in propagation in the 3 spots * that were made between 22:00 and 22:22 UTC, that show a very rapid chang in propagation. (See the red arrows)

Thanks to Roger for the interesting experiments with WSPR.