SMART antenna testing range
SMART is short for SMall Antenna Radiated Testing. The SMART facility is available for minimally-invasive measurements of electrically-small, and smart, antennas at frequencies above 400 MHz. The main challenge was to mount 'omni-directional' antennas to minimise the influence of the antenna support and feed cable.
The SMART range was built for companies and research groups to characterise accurately antennas used for wireless communications applications. These include smaller, often wearable or implantable, devices with small antennas.
This facility will be of interest to you if you are involved in the design, manufacture and use of single and multiple (adaptive and MIMO) array antennas for:
- GSM/3G/ LTE/ 4G (and beyond) mobile phones and base stations
- Wireless Local Area Networks (WLANs), e.g. IEEE802.11/ a, b, g, n
- Wireless sensors and body area networks (WSN and BAN)
- Bluetooth, Zigbee, UWB and the (IEEE 802.15) family
- WIMAX (IEEE802.16) and Wide Area Networks
- Broadcast systems, e.g. DRM/ DAB/ DVB-T/H/T2
- Cognitive and software defined radio (SDR) applications
Benefits of the SMART range
Minimally-invasive measurements: These are achieved by supporting antennas on a thin robust Kevlar tube, or on polystyrene foam blocks. The coaxial cable can be replaced by a miniature RF-to-optical transducer made by Seikoh-Giken. This RF-optical link is so small that it causes minimal disturbance to coin sized patch antennas. It has a metal box 20 mm x 10 mm x 10 mm on which is mounted an SMA connector. The main advantage of the transducer is where the antenna causes common mode current on the feeder coaxial cable that can distort the antenna radiation pattern by typically 10 dB. Replacing the cable by optical fibre addresses this problem. The transducer is part of the opto-electric field sensor system that NPL helped Seikoh-Giken develop.
Four parameters measured: Gain, reflection coefficient, radiation pattern, and efficiency of antennas.
Adaptability: The Kevlar mast that holds the receiving antenna can be replaced by a wooden turntable. The radiation pattern of a body-mounted antenna is measured with a body-phantom or person on the turntable.
- The range is at NPL in a screened room 7 m long x 6.2 m high x 6.2 m wide
- The anechoic absorber has low reflectivity from 400 MHz to 110 GHz. The absorber is covered by white polystyrene tiles for improved room illumination.
- The rollover-azimuth positioner enables automated measurement of radiation patterns over a sphere, for antennas weighing up to 2 kg. The post processing software gives Cartesian and 3D visual displays of the results.
- The roll mast can be replaced by an azimuth turntable with a vertical loading of 363 kg, e.g. for body antennas.
- A source tower can be positioned to give a range length from 0.1 m - 3.5 m.
- The antenna supports have very low reflectivity to achieve the lowest uncertainty measurements.
- Addresses the fundamental problems of radiation from common mode currents (encountered when characterising low gain and/or poorly balanced antennas) and reflections from antenna supports and antenna feed cables.
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