Antenna Measurement Range
Understanding Antenna Ranges
Antenna measurement requires controlled, interference-free environments that approximate free-space conditions. The choice of measurement range depends on antenna size, frequency, accuracy requirements, and budget.
Range Types
- Far-field outdoor: Long range (10s-100s of meters). Source at far-field distance. Reflections from ground are the primary challenge.
- Far-field indoor (anechoic chamber): Absorber-lined room. Excellent for small-medium antennas. Size limited by chamber dimensions.
- Compact range (CATR): Uses a large reflector to create a plane wave in a shorter room. Far-field conditions at 1/3 the normal distance.
- Near-field scanner: Measures near-field amplitude and phase on a planar, cylindrical, or spherical surface. Transforms to far-field mathematically. Most compact.
Frequently Asked Questions
What is an antenna measurement range?
A facility for accurate antenna pattern and gain measurement. Types: outdoor far-field, indoor anechoic chamber, compact range (reflector), and near-field scanner. Each trades size, cost, and capability.
What is a compact antenna test range?
A CATR uses a large precision reflector to convert a spherical wave from a feed into a plane wave, creating far-field conditions in a much shorter room. Typically 1/3 the far-field distance. The reflector must be very precise (surface RMS < lambda/50).
When should I use near-field measurement?
For large antennas where the far-field distance is impractical (e.g., 1m dish at 10 GHz needs 67m far-field distance). Near-field scanning measures at 3-10 lambda from the aperture and computes the far-field pattern mathematically.