VSAT index page Focal length of parabolic dish How to make inclinometer How to find offset angle of dish Setting up a polar mount satellite dish with motor drive

# Setting up a polar mount satellite dish. Axisymmetric type with feed in the centre (Example 2)

In this example, the satellite dish reflector is circular, with feed on centreline. The beam is at right angles to the dish backing structure ring.

 Polar mount dish offset tilt angle Polar mount main axis angle

Identify your latitude from a map or GPS receiver. North of the equator latitude is positive, the further away from the equator the greater the number. South latitudes are negative. Work it out as a decimal number. There are 60 minutes in a degree.

Examples:
51 deg 30 minutes north = 51.5 deg
50 deg 15 minutes north = 50.25 deg
45 deg 45 minutes north = 45.75 deg
20 deg 10 minutes south = - 20.166 deg
30 deg 20 minutes south = - 30.336 deg

Go to the satellite TV angle calculator and input your latitude. You can input zeros for the longitude of your site and the orbit longitude of the satellite, since longitude is irrelevant to the setting up of a polar mount. You are only interested in pre-calculating the polar mount main axis angle and the polar mount dish offset tilt angle.

Set the polar mount main axis angle using the scale in Fig 2 above. You can check the angle with an inclinometer applied to the metal edge that is parallel with the main axis.

Set the polar mount dish offset tilt angle using the small scale at the top, shown in Fig 1.

Having set the two angles really carefully, centre the actuator and point the whole head assembly to due south by rotating the canister on the pipe at the bottom.

 Page amended 23rd March 2006, amended 24 Feb 2015