Two different methods are used for antenna pattern measurements: Frequency Domain measurement (FDM) and Time Domain measurement (TDM). Every method has its advantages. The TDM allows eliminating the reflections from adjacent objects using sufficient time window. Therefore it is possible carry out TDM indoors without unechoic chamber. It enables to measure antenna pattern for different frequencies simultaneously using Fourier transform. In this case the full measurement requires less time. From other hand FDM enables achieve better dynamic range and it is unique possible method for measurement with narrowband antennas.
The sampling scopes designed by Geozondas Ltd. enable to carry out antennas measurement both in Time Domain and in Frequency Domain. There are two operating modes in this scope: internal triggering mode and external triggering mode in frequency range to 20 GHz. The last enables to use this sampling scope for antenna measurements in Frequency Domain using reference antenna for triggering.
In TDM the Pulse Generator generates short pulse with duration about 25-35 ps. Such pulse enables to measure in frequency band from DC to 26 GHz. Signal from Pulse Generator is applied to transmitting antenna. Signal from receiving antenna (antenna under test) which is located on rotating table is applied to one channel of sampling scope. During antenna pattern measurement in TDM for various orientation angles the pulse signal received by receiving antenna is recorded and its spectrum is calculated using Fourier transform.
In FDM the Microwave Generator is connected to transmitting Antenna. Signal from receiving antenna is applied to one channel of sampling scope. To other channel of sampling unit is applied the signal received by reference antenna which is located near from measured antenna. The same signal from reference antenna is applied to the microwave trigger head which output is connected to synchronization input of sampling scope.
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| Name |
Complete set |
| Far Field Antenna Measurement System Without Anechoic Chamber |
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