Lamp post obstacle.

[bureaucrazy]

Hi,

I wish to install a triax td88 dish (90cm) with 2 quattro lnbs (inverto ultra). 1 to pick up astra 4a at 175 degrees (azimuth) and the other lnb for hotbird 13 at 166 degrees (azimuth). The Astra 4a signal is very weak where I live (east anglia) but the hotbird signal is good.

The idiots at my local council have put a metal lamp post about 15cm wide in front of my house (3.5m from the front elevation). According to my measurements, if I place my dish at the furthest away point on the border of my neighbors house, the line of sight from the dish to 175 degrees for Astra 4A just barely squeezes past the side of the lamp post.

However, at 166 degrees (for hotbird 13), the lamp post obscures part of the dish.

My questions are:

1. Will the closeness of the lamp post have any effect on the Astra 4A reception given it is (just barely) a clear line of sight?
2. Will the "shadow" of the lamp post merely reduce the signal for the hotbird directly proportional to the surface area of the dish obscured?
3. Is it more complicated than that? e.g. wave diffraction/interference caused by the proximity of a metal lamp post. Does more signal bounce from the centre of the dish than the sides?

I have calculated that the surface area not in shadow will still be bigger than a 70cm dish.

The only other place for the dish obscures a window.

Will I be OK or not?


Thanks guys

 

[rolfw]

Doesn't sound like it'll be a problem, but remember that dishpointer is not inch perfect.

 

[bureaucrazy]

you mean the azimuth quoted on dish pointer may be slightly off? How much can it vary in practice? or is it the difference to do with the tollerance of a compass? I caculated the angles using a photo from google maps and a geometry set having measured the position of the lamp post with a tape measure.

 

[esto]

A lamp-post is pretty thin, altho 3.5m in front of the dish is pretty close, so it will probably have an impact. But unless you live in an open field, you will always have to battle some obstructions. Just do trial and error and see what happens. Move the dish around to any other possible locations. A bigger dish and low-noise LNB's are always good at finding signals with obstructions in the way.