Advertisements

Archive for October 22nd, 2016

Satellite Dish Mounting Angle in Norway

A friend asked why Norwegians point their satellite dishes at the ground. After maneuvering Google Streetview around Vadsø for a while, I found a dish in profile:

TV satellite dish - Vadso Norway

TV satellite dish – Vadso Norway

Turns out geostationary orbit is way low, as seen from the top of the world. A bit of doodling shows it’s only 11° above the horizon at 70° N:

TV Satellite Dish - Horizon Angle at 70° N

TV Satellite Dish – Horizon Angle at 70° N

TV satellite antennas have an offset-fed reflector, with the receiver in the lump at the end of the spine sticking out from the bottom of the dish, so as to not obstruct the signal entering the dish. Even though the plane of the reflector points downward, the signal reflected to the receiver comes in from above.

Ain’t science trigonometry grand?

Advertisements

7 Comments