[UK-CONTEST] Monobanders and height

Mon May 3 03:34:07 PDT 2010

Now were did I see that narrow peninsular with a 50m vertical drop to 
the sea....

On 03/05/2010 09:48, G3RIR wrote:
>   For the record any discussion 100ft antennas for NFD should take into
> account the rules which show a maximum height of 20m or about 66ft
>
> Neil, G3RIR
>
>
> 2. Sections: All sections are multi-operator. This is a portable contest as
> defined in General Rule 6.
> (a) Open Section. There is no restriction on the number or type of antennas,
> but the maximum height must not exceed 20m.
> (b) Restricted Section. One antenna only which must be a single element
> having not more than two elevated supports and not exceeding 11m above
> ground at its highest point.
> (c) Low Power Section. Same as the Restricted Section with power further
> limited to 10W output. Additionally, this section has a time limit of 12
> hours. Off-periods must be a minimum of one hour and should be listed on the
> summary sheet or soapbox section of the Cabrillo header.
>
>
>
>
> -----Original Message-----
> From: uk-contest-bounces at contesting.com
> [mailto:uk-contest-bounces at contesting.com] On Behalf Of Andy Cook, G4PIQ
> Sent: 03 May 2010 09:56
> To: uk-contest at contesting.com
> Subject: Re: [UK-CONTEST] Monobanders and height
>
> Callum,
>
> I think you'll find some take-off angle data in the ARRL Antenna Handbook
> (don't have a copy myself), but what you'll see from there is that it's all
> statistical, so it's about the likelyhood of a particular angle on a
> particular path at a particular time of year. I know from experience this
> differs with time, and also with day (which is presumably linked to what
> hop-mode-mix is dominant on a particular day on a particular path). To a
> large extent, low angles are dominant at the start and end of openings.
>
> On a practical note, I've have opertated a number of times with antennas at
> 55ft / 95ft mix both available. In general on shorter paths (Eu / East Coast
> W) there's not so much to choose between them, but the difference is more
> pronounced on the longer paths and early / late in openings and marginal
> forward-scatter paths. It's not often that the lower antenna is better than
> the higher one, but from time to time (I've seen it on Eu paths on 20m in
> the summer, intense W openings on 15, and on a similar basis I have
> occasionally seen a dipole @ 80ft better than the 4 square on 80m to the
> East Coast of W during strong openings). If I could have only one antenna it
> would clearly be the one at 100ft, but if I was doing a field-day contest
> with the majority of traffic to Eu, I wouldn't worry too much if I only had
> the 60ft one available.
>
> 73,
>
> Andy, G4PIQ
>
> -----Original Message-----
> From: uk-contest-bounces at contesting.com
> [mailto:uk-contest-bounces at contesting.com] On Behalf Of Callum MØMCX
> Sent: 02 May 2010 17:18
> To: uk-contest at contesting.com
> Subject: Re: [UK-CONTEST] Monobanders and height
>
>
> In CQWPX, we ran a pair of A3S antennas; 100 feet and 50 feet. The 100
> footer won everytime; both EU and DX.
>
> Although we'll have a 60 footer available for FD, we won't have time and
> resources to do both towers.
>
> We have all our antennas modelled but there appears to be a knowledge gap as
> regards take off angles. I can't find a reliable source of information
> outlining the variables that affect required take-off angle for required
> range on a per frequency basis.
>
> A case in point is 80m. I now have real-world data for a dipole at 140 feet;
> the answer is that it will only run DX, (but it's great). The footprint only
> starts to land at around 2,000 miles. For 20m, I've no real world data
> unfortunately.
>
> If I can get some reliable data tables together, that would assist the
> decision making processes.
>
> Callum McCormick
> Via iPhone
> 07976 631881
> http://www.m0mcx.co.uk/
> http://www.barclayanderson.com/
>
> On 2 May 2010, at 16:42, "Clive GM3POI"<gm3poi2 at btinternet.com>  wrote:
>
>    
>> Callum,
>>     With all the work involved in doing either project you would be
>> well advised to model the difference using the ARRL handbook software
>> by Dean Straw (HFTA).
>>     You should input the main directions from the location of the
>> proposed antenna and use say a 2el 20m to represent the A3S and a 3el
>> mono at the various heights. Dependant on the local ground slope you
>> may get some surprising results.
>>     The only time surprises don't happen is when you have flat ground
>> around the Station, because you need roughly twice the antenna height
>> over  gentle sloping ground. 73 Clive GM3POI
>> ----- Original Message -----
>> From: "Callum MØMCX"<callum at mccormick.uk.com>
>> To:<uk-contest at contesting.com>
>> Cc: "James Thresher"<James.Thresher at Jaama.co.uk>; "G4MKP"
>> <terryburbidge at blueyonder.co.uk>
>> Sent: Sunday, May 02, 2010 12:07 PM
>> Subject: [UK-CONTEST] Monobanders and height
>>
>>
>>      
>>> Our team is trying to establish the likely real-world difference on
>>> 20m band, in extreme field-day style contesting, between an A3S at 60
>>> feet and a full-sized 3 element  monobander with 16 foot boom at 100
>>> feet.
>>>
>>> Does anyone have experience of these variables?
>>>
>>> Callum McCormick
>>> Via iPhone
>>> 07976 631881
>>> http://www.m0mcx.co.uk/
>>> http://www.barclayanderson.com/
>>> _______________________________________________
>>> UK-Contest mailing list
>>> UK-Contest at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/uk-contest
>>>        
>>
>> _______________________________________________
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>>      
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