Ministry of Defence Magnetic Range, Portland

The Ministry of Defence Magnetic Range, (a.k.a. the Portland Bill Land Magnetic Facilities or the Defence Test and Evaluation Organisation Establishment) is a Ministry of Defence site used for magnetic measurement on the Isle of Portland, Dorset, England. The facility is situated at Portland Bill, where tests can be performed well away from stray electric and magnetic fields.

History
The site was chosen during the 1960s for magnetic measurement due to Portland Bill's remoteness and magnetic cleanliness. As Portland stone is non-magnetic, as well as the site's remoteness, the site is free from any magnetic disturbance such as heavy traffic, and as a result, very small magnetic fields from equipment can be measured with a very high degree of accuracy. The site is used to magnetically assess any item, but mainly MCMV and EOD equipment. Magnetic compasses can also be tested. The magnetically controlled environment is suitable for both Electronic Warfare Calibration and Magnetic Assessment Services. The site is capable of simulating the Earth's magnetic field at any point, and measuring the effect on the test object, whilst the Earth's field can be manipulated to zero, or be broken into its vertical and horizontal components. The site also provides consultancy, training and data services. The unique facility is both notified and approved by the Maritime and Coastguard Agency and is the only accredited centre for Type Approval of Magnetic Compasses and Binnacles in the United Kingdom.

On the site is part of the Portland Raised Beach - a beach which represents the significant changes fluctuations in sea level and climate change during the last Ice Age, and largely consists of shelly and sandy pebble deposits. The other part of the beach is accessible to the public at their own risk.

Facilities
The site holds various facilities. The main Land Magnetic Range is a secure and magnetically stable environment, used to measure the magnetic fields found in Mine Counter Measure Vessel equipment. The range uses inbuilt coil systems which enable the Earth's magnetic field to be reduced to zero, simulate anywhere on the planet, or provide only the vertical or horizontal portion of the Earth field to pass through the item under test, which an equivalent Sea Range cannot do. The Special Magnetic Effects area has the provision of high power coil systems which can replicate the high magnetic fields passing through equipment on vessels while undergoing magnetic treatment. This is additionally used for the pre-magnetisation of EOD equipment just before its magnetic measurement. The Explosive Ordnance Disposal (EOD) test section has the ability to measure the minute magnetic fields retained in EOD equipment inside a secure magnetically stable environment, whilst Magnetic Surveys check for potential contaminating magnetic fields in areas off site where MCMV and EOD equipment will be stored and worked on.

The Compass Test Centre inspects and tests magnetic compasses, whilst also delivering them to RAF stations across the UK. The Compass Base Calibration Surveys is a designated area of survey and certification, used for accurate swinging of Aircraft Navigation Equipment for both military and civilian airfields. The Small Arms and Medium Calibre Ranges feature two 50 metre and one 200 metre tunnels, along with various open ranges. Offering a full range of conditioning, the max range is 1500 metres against land targets and 18 kilo-metres out to sea. The Electronic Warfare Calibration section is a check facility which can 'calibrate' electronic countermeasures on RN vessels while operating at sea.