What is a compact antenna test range?
A compact antenna test range (CATR) uses an offset parabolic reflector, illuminated by a feed at its focus, to convert the spherical wave into a plane wave over a quiet zone only a few meters from the reflector. It allows far-field measurements of electrically large antennas, and over-the-air testing of mmWave devices, in a chamber far shorter than 2D²/λ.[1][2]
How does a CATR produce a plane wave?
Ray optics: rays from the focus reflect parallel to the axis, giving uniform phase in the aperture. Edge diffraction would cause ripple, so reflector edges are serrated or rolled; the usable quiet zone is typically about half to two-thirds of the reflector size.[1]
What limits a CATR?
At low frequencies the reflector must be many wavelengths across to work properly; at high frequencies surface accuracy must be a small fraction of λ. Feed spillover and chamber reflections set quiet-zone ripple.[1]
Why are CATRs used for 5G mmWave?
mmWave devices integrate antennas with radios, so radiated testing is mandatory, and the device’s radiating aperture position may be unknown; a CATR provides far-field conditions in a compact, shielded chamber, and is one of the indirect far-field methods accepted by 3GPP for FR2 testing.[2]
Frequently asked questions
Is a CATR a near-field method?
No; it creates far-field conditions directly.
What is a dual-reflector CATR?
A design using two reflectors to improve quiet-zone quality and cross-polarization.
How large is a quiet zone?
Roughly half to two-thirds of the reflector dimension.
See also
References
Online sources accessed October 21, 2026; printed works cited by edition. See all sources.
- “IEEE Recommended Practice for Antenna Measurements (IEEE Std 149-2021)”. IEEE Antennas and Propagation Society. 2022.
- “3GPP TS 38.101-1 and 38.101-2: NR User Equipment radio transmission and reception (FR1 and FR2)”. 3GPP. current release.