The original source for the "2 dB improvement" quote probably comes from
QST, September 1966, "Station Design for DX" by W3AFM:
"Incidentally, in progressive antenna changes at W3AFM, increments of
only 2 dB in antenna gain have opened up, in each case, a new layer of
workable central-Asian DX."
73,
Steve, N2IC
Jim Smith wrote:
> Hi Jose,
>
> What an interesting analysis. Thanks for doing this Jose.
>
> I was particularly intrigued by your statement that a 2 db improvement
> in signal strength will provide access to another level of stations. A
> little further on you state that an additional 2 dB will open an
> additional level of stations.
>
> Where do these these figures come from?
> Generally accepted by the contesting community?
> Statistical analysis performed by someone?
> Your personal experience?
>
> Seems to me that this info would be very useful when making station
> design decisions.
>
> 73, Jim Smith VE7FO
>
> José Nunes CT1BOH wrote:
>
>>Why did the Canadians (PT5M) beat the Americans (PW5C) in WRTC 2006?
>>
>>
>>
>>
>>
>>The answer to this question is actually quite simple: Not enough Americans
>>worked PW5C on 40 meters. No, it was not a national boycott to the American
>>team by their fellow compatriots as you will see below…
>>
>>
>>
>>After reading the answer to the first question I will just ask one more
>>question:
>>
>>Do we need a handicap system for WRTC's?
>>
>>
>>
>>The 2006 WRTC is over and done, and to start with I think it is not enough
>>to say the PY's did a FANTASTIC job. I repeat a FANTASTIC job. Although I
>>was not able to attend, because of my first child birth, everyone who was
>>there and I talked to had nothing but praise words to the incredible effort
>>put up to make WRTC 2006 the best WRTC so far.
>>
>>
>>
>>I worked the event from home and followed with particular interest the hour
>>by hour live scoreboard and the battle between the first two teams PT5M
>>(VE3EJ + VE7ZO) and PW5C (N6MJ and N2NL) with PW5C leading the first hours
>>and then a turn around with PT5M claiming victory.
>>
>>
>>
>>With all the logs available on WRTC official web site I retrieve these two
>>and begun analyzing them to try to explain why such a turn around in the
>>last hours of the event.
>>
>>
>>
>>Just looking at raw QSO data, plotting the difference of QSO's between PW5C
>>and PT5M, it is interesting to note that the difference in QSO's between the
>>two was always up and down between 0 and around 50 QSO's from the start of
>>the contest at 12:00z the first day until 03:00z the second day (note: the
>>Americans were leading in score because they had a better multiplier total).
>>At 03:00z the difference between the two teams was just two (2) QSOs. After
>>03:00z until 10:00z the Canadians gained about 215 QSOs. After 10:00z and
>>until the end of the contest at 11:59 again there was not much difference in
>>the effort of the two teams to work QSO's. The edge the Canadians gained in
>>QSO's during 7 hours of the contest (03:00-09:59z) eventually was enough to
>>overcome their multiplier disadvantage and win the event.
>>
>>
>>
>>The astute readers will realize one very important fact to explain why the
>>answer to the first question is so simple: propagation on 40 dies between
>>PY5 and Europe around 03:00Z as all the logs demonstrate it. 20 meters was
>>dead and 80 was not productive. All there was to work was USA and the
>>American continent, as the rest of the world QSOs was negligible. Repeat
>>there was no Europe to work as all the logs show it. It is also important to
>>note that after 10Z with sunrise approaching contesters tend to move to the
>>high bands.
>>
>>
>>
>>Click the link below to see the graph (at 13:24 for instance a value of -43
>>means PW5C is 43 QSO's behind PT5M)
>>
>>
>>
>>http://ct1boh.planetaclix.pt/wrtc/pt5mvspw5c.JPG
>>
>>
>>
>>Wow! What happened in those 7 hours between 03:00z and 09:59 that dictated
>>the final outcome of the WRTC 2006 winner?
>>
>>
>>
>>During those 7 hours both stations were on the low bands (mainly 40 and
>>occasionally on 80), but their efforts netted very different results, and
>>the key element is the fact that because of propagation characteristics in
>>Brazil and the low part of the sunspot cyle, the contest during those 7
>>hours turned basically into a 40 meter/USA only event.
>>
>>
>>
>>Let's check PT5M QSO's 03:00 – 09:59z
>>
>>
>>
>>20 meters: 2 QSO's
>>
>>40 meters: 477 QSO's
>>
>>80 meters: 56 QSO's
>>
>>
>>
>>Looking for 40 meters the continent distribution was:
>>
>>
>>
>>Europe 8 QSO's
>>
>>Japan 20 QSO's
>>
>>Other 97 (basically North and South America) QSO's
>>
>>USA 352
>>
>>
>>
>>Let's now check PW5C QSO's 03:00 – 09:59z
>>
>>
>>
>>20 meters: 0 QSO's
>>
>>40 meters: 272 QSO's
>>
>>80 meters: 50 QSO's
>>
>>
>>
>>Looking for 40 meters the continent distribution was:
>>
>>
>>
>>Europe 3 QSO's
>>
>>Japan 5 QSO's
>>
>>Other 62 (basically North and South America) QSO's
>>
>>USA 202 QSO's
>>
>>
>>
>>During these 7 hours, while on 40, the Canadians ended up working a lot more
>>QSO's and those QSO's were the difference to their victory against the
>>Americans.
>>
>>
>>
>>And what were the state side boys doing these hours? Well they couldn't do
>>much, they were crying like babies but mom and daddy did not come to feed
>>them…They were calling CQ, CQ, CQ, CQ,CQ and getting not many answers.
>>
>>
>>
>>Let's check for every one of these 7 hours, how many minutes each team had
>>with 0 (zero) QSOs:
>>
>>
>>
>>Hour PT5M PW5C
>>
>>3z 10 21
>>
>>4z 11 32
>>
>>5z 17 22
>>
>>6z 12 15
>>
>>7z 22 37
>>
>>8z 30 42
>>
>>9z 24 41
>>
>>
>>
>>Total 126 210
>>
>>
>>
>>In these 7 hours the state side boy's team had 210 minutes with zero QSOs,
>>and I bet they were not sleeping or taking a time way to pee….
>>
>>
>>
>>If we now look to the minutes with QSOs we can check that the Canadians had
>>294 minutes with QSOs – 535 QSOs at a rate of 1,82 QSOs per minute and the
>>Americans had 210 minutes with QSOs – 322 QSOs at a rate of 1.53 QSOs per
>>minute, i.e. the Canadians were working stations faster and at least two
>>levels of stations PW5C could not work or copy as we will see why ahead in
>>the text below.
>>
>>
>>
>>Now if you remember, in the first 15 hours of the contest both teams worked
>>almost exactly the same number of QSOs:
>>
>>PW5C 1757 QSOs and PT5M 1759 QSOs
>>
>>
>>
>>So if these two teams had such similar performances why such a difference
>>now on 40?
>>
>>
>>
>>The answer is LOCATION/TERRAIN and LOW ANGLES…
>>
>>
>>
>>With latitude and longitude coordinates of both locations PW5C 27 44 20S, 48
>>30 41W, PT5M 26 08 52 S, 49 10 47 W) and Google Earth it is possible to
>>check the PY5 – USA path from the two sites, and use the terrain data to
>>analyze the take off angles of the signals using HFTA (N6BV great
>>program).. For this analysis I used the PY1 to US data available in the ARRL
>>Antenna Book CD.
>>
>>
>>
>>Click below to see the terrain characteristics of both teams toward USA and
>>the figure of merit of the two antennas on 40 taking into account the
>>terrain and the angle information of the signals between PY5 and the whole
>>of USA.
>>
>>
>>
>>Terrain graphs:
>>
>>http://ct1boh.planetaclix.pt/wrtc/pt5m_pw5c_terrain.JPG
>>
>>
>>
>>Image of view of PT5M towards USA:
>>
>>http://ct1boh.planetaclix.pt/wrtc/pt5m_usa.jpg
>>
>>
>>
>>Image of view of PW5C towards USA:
>>
>>http://ct1boh.planetaclix.pt/wrtc/pw5c_usa.jpg
>>
>>
>>
>>Figure of merit of antennas taking into account terrain:
>>
>>http://ct1boh.planetaclix.pt/wrtc/pt5mvspw5c_fom.JPG
>>
>>
>>
>>
>>
>>What's so interesting about these graphs?
>>
>>
>>
>>To start PT5M had a geographical location advantage towards USA over PW5C.
>>
>>Now let's check the low angles and the antenna performance (Dbi) according
>>to the terrain data:
>>
>>
>>
>>First, PT5M 40 meter antenna/terrain has a FOM (figure of merit) of 6.9 DBi
>>compared to 4.7 DBi of PW5C. Those 2.2 DBis open a level of stations.
>>
>>Second looking at the very low angles, surely used by signals for this part
>>of the cycle we have:
>>
>>
>>
>>Angle PT5M PW5C
>>
>>
>>
>>1 -3.7 -7.0
>>
>>2 1.2 -2.0
>>
>>3 3.4 -0.6
>>
>>4 4.4 -0.9
>>
>>5 5.4 -1.6
>>
>>6 5.5 3.4
>>
>>7 3.8 3.9
>>
>>8 4.9 4.3
>>
>>
>>
>>>From 1 to 6 degrees on average PT5M is 4.15 DBi better than PW5C. It's two
>>levels of stations.
>>
>>
>>
>>PT5M beats PW5C all the time in the low angles, and these zero to eight
>>degree angles represent statistically 34% of the incoming signals.
>>
>>
>>
>>No wonder PW5C is about 40% down on QSO's on those 7 hours against PT5M.
>>
>>
>>
>>It is clear to me Location/Terrain was the factor for N6MJ/N2NL loosing all
>>those QSO's during those 7 hours on 40/80 between 03:00 and 09:59z.
>>
>>
>>
>>Note I'm not saying N6MJ/N2NL should have been the winners, although I have
>>my own thoughts. We do not know what their performance would be at the
>>command of PT5M on those 7 hours. Nor we know what VE3EJ/VE7ZO would do at
>>the command of PW5C from 12:00 to 03:00z and then from 10:00 to 11:59z. But
>>the fact remains that PW5C lost ground and eventually the contest because of
>>what happened from 03:00 to 09:59z on 40 meters.
>>
>>
>>
>>Anyway, what is all this about?
>>
>>
>>
>>Well it is clear that WRTC is not a plain level field event!
>>
>>
>>
>>I just looked into two stations but I'm sure a lot more differences exist,
>>and unless everyone goes to the flatlands of Russia , or to BS7H rocks with
>>verticals probably no WRTC will be even, unless a handicap system is
>>developed. We have the technology to adjust each location to it's true radio
>>potential, using programs like HFTA. Perhaps then, with a handicap system,
>>WRTC will truly measure team operator performance.
>>
>>
>>
>>73
>>
>>José Nunes
>>
>>Contest CT1BOH - www.qsl.net/ct1boh
>>_______________________________________________
>>CQ-Contest mailing list
>>CQ-Contest@contesting.com
>>http://lists.contesting.com/mailman/listinfo/cq-contest
>>
>>
>
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