You will need planning permission for:

• Antenna facing onto and visible from the highway
• Antenna on a building where the building exceeds 15 metres in height
• More than two antennas

Other developments may be permitted if the following conditions are met:

• The antenna must not exceed 100cm in length
• If installed on a chimney, the length of the antenna cannot exceed 60cm
• Antennas installed on a roof with a chimney must not exceed the height of the chimney or 60 cm above the ridge tiles, whichever is lower
• On a roof without a chimney, antennas must not protrude above the ridge
• Where attached to a chimney, the antenna must not protrude above the chimney
• Antennas must not exceed 35 litres in cubic capacity

So far as is practicable, antennas should be sited to minimise their effect on external appearance of building. For guidance on whether you need planning permission and where you can place your dish check out the Planning Portal’s Antennae Guide.