Antenna test range



Measurement of installed antenna performance on Fokker 100 scaled model
The antenna test range (AMA) is used to determine the radiation or receiving properties of antennas in the far field. For this purpose, the device under test (DUT) is mounted on a pedestal and rotated, while magnitude and phase of the electromagnetic field are measured. In this way, antenna pattern and gain can be determined in the frequency range of 100 MHz to 110 GHz. For a full 3D-diagram, at least 2 rotational axes are required. Besides monitoring the antenna development, also the installed performance of antennas mounted on satellites, airplanes, rockets as well as land and sea vehicles can be investigated and assessed. The measurements can be taken using original objects or their scaled models.

The main units of the test range are:

  • A pedestal to position the DUT and rotate around a horizontal or vertical axis. Depending on the size and weight of the test object, different pedestals can be employed. For light to medium-weight antennas or objects (up to 225 kg), a moveable non-metallic tower is used. For measurements on highly directional and heavy antennas (up to 1000 kg) a tri-axial pedestal (azimuth over elevation over azimuth) located on top of a metallic tower serves this purpose.
  • The pedestal control, to localize the angular target position by passing on the coordinates to the computer which in turn can also reposition the target on the pedestal. For recording the antenna pattern, it scans along the selected rotational axis in a given angular range at a constant angular speed. During the rotation, the pedestal controller transmits trigger pulses in pre-defined angular steps to the receiver, which records the measured data. The positioning accuracy is dependent on the particular pedestal in use and lies within the range of ± 0.01° to ±1°.
  • A stable transmitter (synthesizer) that generates a signal at a predefined frequency and signal level. The DUT usually radiates this signal. A signal branched off from the source via a directional coupler is fed by a coaxial cable to the reference channel of the receiver.
  • A receiver that receives the radiated signal from the DUT in amplitude and phase for the respective target positions via a parabolic dish. An automatic network analyzer is employed which also serves as a microwave receiver.
  • A PC that controls the measurement procedure and collects, stores and processes the data.
  • For the measurement of the antenna input impedance and scattering parameters in RF circuits, an automatic network analyzer (NWA) including an RF probing measurement system is available.

The facility has been used in many projects for the characterization of single radiators and arrays within the development of smart antennas for communications and navigation, mainly in Ka- and L-band. A special highlight was the investigation of the installed performance of an antenna array for navigation mounted on a Fokker 100 scaled model to validate various simulation results. The AMA has also been employed for measurement orders by external contractors.


Contact
Wahid Elmarissi
German Aerospace Center

Institute of Communications and Navigation
, Navigation
Tel: +49 8153 28-2340

Fax: +49 8153 28-2328

E-Mail: Wahid.Elmarissi@dlr.de
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