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40 Foot Anechoic Chamber

Cloudsat on upgrader near-field scanner
The 1.85 m Cloudsat antenna measured at 94 GHz on the cylindrical near-field scanner

The 40 foot anechoic chamber is twenty feet square in cross section and has an overall length of forty feet. All chamber surfaces are lined with pyramidal microwave absorber having the characteristics given in the table below.   

These characteristics are such that the range is normally used above X-band. The cylindrical range uses a premium optical turntable that enables accurate measurement of antennas to at least 94 GHz.   Scale model testing has permitted assessment of antennas designed for lower frequencies in this chamber. The large 9 ft rotation radius enables measurement of large structures such as the 2.5 m x 3 m Wide Swath Ocean Altemeter (WSOA) reflectarray shown below.


Jeff Harrell in chamber   controller
Dr. Jefferson Harrell working on the Aquarius spacecraft Scale Model   Aquarius scale model on the cylindrical near-field scanner at 13.3 Ghz

Table of Low-Frequency Limits of Indicated Reflectivity

Application
Reflectivity

Material

Side
Walls

Back
Walls

Center
Band

-30

-40

-45

-50

 

 

 

 

 

 

 

 

EHP-5-CL

*

 

*

1.5 GHz

3.0 GHz

6 GHz

25 GHz

EHP-8-CL

 

*

 

1.0 GHz

1.5 GHz

3 GHz

25 GHz

A wide-band tunable, phase-locked loop amplitude and phase receiver is directly applicable over multiple bands; however, the receiver mixer (mounted near the antenna under test) must be changed from band to band.  

Cloudsat on upgrader near-field scanner
WSOA reflectarray meaured at Ku-band


The equipment in the 40 foot anechoic chamber is currently configured for cylindrical near field measurement. Patterns have been recorded in the 40 foot chamber over the frequency range of 7.1 GHz through 94.0 GHz.

The chamber is equipped with a track mounted adjustable separation azimuth positioner. The upper surface or mounting plane of the positioner is nearly flush with the chamber floor.  This permits easy removal of the existing traverse table assembly and installation of other test antenna support structures when required. Although this chamber is located below ground level, rear wall access doors are provided for access to the chamber through a ground level anteroom equipped with a 1-ton crane for moving the antenna under test into the chamber.  The anteroom also provides a climate controlled space for hardware assembly.



Location: Mesa Facilities Map