Antenna measurements

An extensive range of calibration services

NPL gives advice on the most appropriate calibration for a range of applications, and carries out calibration of a wide variety of antenna types, including:

• monopole
• tuneable dipole
• biconical
• log-periodic dipole array
• biconical-log hybrid antennas
• conical log-spiral
• loop antennas
• horn antennas.

These antennas are used for electromagnetic compatibility (EMC) testing (to meet the requirements of EMC Directive 2014/30/EU), satellite communications and Earth remote sensing. NPL has developed a comprehensive range of facilities for calibrating antennas covering the frequency range from 20 Hz up to 110 GHz. These include an open area test site, fully anechoic room (FAR), extrapolation range, spherical near-field scanner and microwave EMC chamber.

Other properties of antennas that we can measure are:

• Reflection coefficient (in order to calculate mismatch uncertainties)
• Balun balance
• Cross-polar rejection
• Phase-centre position
• Radiation patterns (if the measurement involves transmission or reception at angles other than the antenna boresight direction, depending how broad the mainbeam is)

Antennas used for EMC conformance testing must be traceably calibrated to national standards for the products to be eligible to carry the CE mark. NPL holds the UK's national standard for field strength, which is based on a calculable dipole antenna that has been valildated on the national standard open field site at NPL. The open field site comprises 60 m x 30 m metal ground plane, flat within ±6 mm over 95 % of its area.

Calibrations can be performed in a fully ferrite-tiled anechoic room down to 30 MHz and in an anechoic chamber up to 18 GHz. Calibrations are UKAS accredited according to the following international Standards:

• CISPR 16-1-6 (BS EN 55016-1-6:2015)
• ANSI C63.5:2017
• SAE ARP 958

NPL advises customers on the most appropriate calibration for their application as well as offering consultancy for measurement of non-standard antennas and for antenna range design and validation. 

Also see the NPL Good Practice Guide No. 73 on Antenna Calibration

Radiating sources

The electric field strength of radiating sources can be measured, above a ground plane or in an anechoic chamber. These sources are commonly used to validate a measurement test site. Common frequency ranges are 30 - 1000 MHz and 1 - 7 GHz.

All the facilities can be hired, please contact us to discuss availability.

Don’t see what you are looking for? Our diverse skill set enables us to provide bespoke solutions. Please contact us to discuss your requirements.

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