On Saturday, 7 May 2022 at 12:49:50 UTC+1, Java Jive wrote:
> On 07/05/2022 10:05, R. Mark Clayton wrote:
> >
> > On Saturday, 7 May 2022 at 00:16:03 UTC+1, Java Jive wrote:
> > SNIP
> >>>

> It's actually 1.1%.

Just worked it out properly and it is 10%.

> >> Now think of the dish sizes for Zones 1 & 2, here's a dish available as
> >> either Zone 1 or Zone 2...
> >> https://www.amazon.co.uk/Satellites-Zone-Satellite-Dish-FreeSat-2-NO-QUAD/dp/B077DQTPYX/ref=sr_1_16
> >> ... which is ...
> >> Zone 1: 60 x 40 cm
> >> Zone 2: 80 x 60 cm.
> >>
> >> The boresight cross-sectional area for each of these dishes is Pi.a.b
> >> where a and b are the semi-major and semi-minor axes respectively. So
> >> we have ...
> >> Zone 1 Cross-sectional Area: 1,885 cm2
> >> Zone 2 Cross-sectional Area: 3,769 cm2
> >> ... so a doubling of cross-sectional area.
> >>
> >> I don't see how a 1% increase in distance can explain a doubling of dish
> >> area!
> >
> > "not that much" about 2.5% based on your figures.
> No, the difference in distance is only 1.1%, and even were it 2.5%, it
> still wouldn't explain a doubling in dish cross-sectional area.

And because the signal falls off with the square of the distance the difference is 21%.

SNIP

On 07/05/2022 21:06, R. Mark Clayton wrote:
> And because the signal falls off with the square of the distance the difference is 21%.

But the gain of the antenna also scales with the square, so the dish
only needs to be 10% wider.

On 07/05/2022 21:06, R. Mark Clayton wrote:
>
> On Saturday, 7 May 2022 at 12:49:50 UTC+1, Java Jive wrote:
>>
>> It's actually 1.1%.
>
> Just worked it out properly and it is 10%.

Nonsense:

Aberdeen (57.13,-2.10)
https://satlex.de/en/azel_calc-params.html?satlo=28.2&location=57.13%2C-2.10&la=57.13&lo=-2.10&country_code=uk

Distance to satellite: 39578.52 km

St Ives, Cornwall (50.20861,-5.4875)
https://satlex.de/en/azel_calc-params.html?satlo=28.2&user_satlo_dir=E&la=50.20861&lo=-5.4875&country_code=uk

Distance to satellite: 39141.72 km

The percentage difference in distance is thus:
100 * (39578.52 - 39141.72) / 39141.72 = 1.1%

St.Ives is on the South Coast at 50 degrees N as in the original
example, Aberdeen at 57 degrees N is significantly further north than
the border at 55 degrees N, yet the difference between their distances
to the satellite is only 1.1%, so the difference between somewhere 50
degrees N and somewhere else 55 degrees N cannot be more than that.

> And because the signal falls off with the square of the distance the difference is 21%.

Again nonsense ...

Ignoring the effects of atmospheric absorption, Aberdeen's signal
intensity will be proportional to
1/39578.52^2
.... which we can write as being equal to ...
K/39578.52^2
.... where we don't know what the value K is, but it doesn't matter, and
St Ives' signal intensity will be proportional to ...
1/39141.72^2
.... which similarly we can write as
K/39141.72^2

The percentage difference between them is thus
100 * (K/39578.52^2 - K/39141.72^2) / K/39141.72^2

The Ks cancel out, and multiplying top and bottom by 39141.72^2 gives us:
100 * ( 39141.72^2/39578.52^2 - 1 )
= 100 * ( 0.978 - 1 )
= -2.2%

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

R. Mark Clayton wrote:

> Originally $ky used 19.2 E, which is about the same longitude as Warsaw, but
> since it went digital it is on 28.2E, which is the about the same longitude
> at central Ukraine.

Directly above a national park in DR Congo

On Saturday, 7 May 2022 at 21:54:13 UTC+1, Java Jive wrote:
> On 07/05/2022 21:06, R. Mark Clayton wrote:
> >
> > On Saturday, 7 May 2022 at 12:49:50 UTC+1, Java Jive wrote:
> >>
> >> It's actually 1.1%.
> >
> > Just worked it out properly and it is 10%.

Oh whoops! - I worked out the difference between central UK and the equator, the difference between different bits of the UK is much less.

OTOH the signal does fall off with the square of the distance.

> Nonsense:
>
> Aberdeen (57.13,-2.10)
> https://satlex.de/en/azel_calc-params.html?satlo=28.2&location=57.13%2C-2.10&la=57.13&lo=-2.10&country_code=uk
> Distance to satellite: 39578.52 km
>
> St Ives, Cornwall (50.20861,-5.4875)
> https://satlex.de/en/azel_calc-params.html?satlo=28.2&user_satlo_dir=E&la=50.20861&lo=-5.4875&country_code=uk
> Distance to satellite: 39141.72 km
> The percentage difference in distance is thus:
> 100 * (39578.52 - 39141.72) / 39141.72 = 1.1%
>
> St.Ives is on the South Coast at 50 degrees N as in the original
> example, Aberdeen at 57 degrees N is significantly further north than
> the border at 55 degrees N, yet the difference between their distances
> to the satellite is only 1.1%, so the difference between somewhere 50
> degrees N and somewhere else 55 degrees N cannot be more than that.
> > And because the signal falls off with the square of the distance the difference is 21%.
> Again nonsense ...
>
> Ignoring the effects of atmospheric absorption, Aberdeen's signal
> intensity will be proportional to
> 1/39578.52^2
> ... which we can write as being equal to ...
> K/39578.52^2
> ... where we don't know what the value K is, but it doesn't matter, and
> St Ives' signal intensity will be proportional to ...
> 1/39141.72^2
> ... which similarly we can write as
> K/39141.72^2
>
> The percentage difference between them is thus
> 100 * (K/39578.52^2 - K/39141.72^2) / K/39141.72^2
>
> The Ks cancel out, and multiplying top and bottom by 39141.72^2 gives us:
> 100 * ( 39141.72^2/39578.52^2 - 1 )
> = 100 * ( 0.978 - 1 )
> = -2.2%
> --
>
> Fake news kills!
>
> I may be contacted via the contact address given on my website:
> www.macfh.co.uk