Nearfield Systems Inc.
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About
1. What are the temperature and humidity requirements for an antenna test range?
2. What is the largest near-field scanner that I can fit in my range?
3. How can I determine the power-handling capability of the absorber in my range?
1. What are the temperature and humidity requirements for an antenna test range?
A nominal temperature range from 20 to 25 deg C (68 to 77 deg F) is acceptable, but during measurements for accurate results, it is recommended to hold the temperature to within +/- 0.5 Deg C (+/- 1 Deg F) ideally, or at least +/- 1 Deg C (+/- 2 Deg F). Humidity levels of 40-60% are recommended. A wider range is tolerable, but may be detrimental to equipment and absorber. Temperature stability requirements are more critical at higher frequencies.
2. What is the largest near-field scanner that I can fit in my range?
Minimum room dimensions are shown on the NSI web site summary page for all of NSI's near-field scanners.
3. How can I determine the power-handling capability of the absorber in my range?
To determine the power-handling cabability of any absorber, consult the absorber manufacturer's specification. As an example, pyramidal absorber from Cuming Microwave is available with three levels of power-handling capability, as shown below.
| Mfg PN | Description | Power-handling | Notes |
|---|---|---|---|
| CRAM-SFC | Standard Pyramidal Foam | 1.25
W/in**2 |
Assumes temperature controlled room, dependent upon frequency and application. |
| CRAM-EVA | Pyramidal Open-cell Foam | 2
W/in**2 (Typical, without forced air cooling) |
Open-cell foam permits air circulation to increase power handling to ~10 W/in**2. |
| CRAM-SFC-HC | Pyramidal Honeycomb | 10
W/in**2 (Typical, without forced air cooling) |
Phenolic coated honeycomb permits forced air to increase power handling capability (see mfg spec). |
For unit conversion, see FAQ #4.
4. Absorber power-handling is often specified in various ways. How can I convert between received power and power density? How can I convert between V/m and W/m**2? How can I convert between W/in**2 and W/cm**2?
To
convert between received power or electric field strength
and power density, see the conversion tool located at:
http://www.giangrandi.ch/electronics/anttool/field.html
To
convert between V/m and W/m**2, see the conversion tool located
at:
http://www.powerwatch.org.uk/science/unitconversion.asp
To
convert between W/in**2 and W/cm**2, see the conversion tool
located at:
http://www.unitconversion.org/unit_converter/heat-flux-density.html