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ANECHOIC CHAMBER BY US AT SAC, ISRO
 
Space Application Centre (ISRO), Ahmedabad, India
   
 
Planar Near Field Chamber for Antenna Measurements
   
12.65m X 10m X 11.5m(L X W X H)
   
Quiet Zone Volume and Location: 9m X 6m X 3m (LXHXW) located in
the center both at length (12.65 m) and height (11.5m) wise and starts from
4.5m to 7.5m from wall behind the Scanner width (10m) wise.

Quiet Zone Performance: Better than –40 dB throughout the quiet zone.
Minimum Frequency of operation: 2.0 GHz.
   
Make: M/S Orbit /FR, Israel
Type: A-1-4953-1-9m-6m-V
Scan Area: 9m X 6m scan area

   
Includes Mounting Bracket, Metal Tower,
Azimuth Positioner and Z Axis Slide.

Design Considerations.
   
The Specular regions are decided from the shadow region of
the quiet zone volume and the Planar Scanner Structures on the
front and back Walls (of the AUT/Scanner), both side walls,
Ceiling and Floor by considering ray –tracing approach.

   
In addition to ray-tracing the size and shape of the specular areas on each walls be determined in terms of Fresnel Zones. It is recommended that at least first three Fresnel Zones be considered as specular regions and be covered by premier absorbers.
   
Scattering by Pyramidal and Wedge Absorbers:
Non-specular scattering of pyramidal and wedge type absorbers has also been considered. By considering the tips of pyramids as regular array of point scatterers interaction of the plane and spherical waves was evaluated were Pyramidal absorbers used at near normal incidences (<45°) while wedge absorbers are used at near grazing incidence ( > 45°).
   
 
 
18”, 12” and 8” thick absorbers of following specs were chosen covering most
important, less important, and least important areas, respectively.Minimum Performance (down in dBs) of Pyramided (FU) absorbers at near normal incidence w.r.t. metal plate is as under at various frequencies
   
Type Thickness
( inches )
Frequency
  2.0 GHZ 5.0 GHZ 18.0 GHZ
FU-18 Pyramidal(A) 18 40 dB 40 dB 40 dB
         
FU-12 Pyramidal(B) 12 25 dB 40 dB 40 dB
         
FU-8 Pyramidal(C) 8 15 dB 25 dB 40 dB
         
FU-FL-24 Walk-on 24 30 dB 30 dB 30 dB
         
FW-18 ( 18 Inch thick wedge ), FW-12 (12 inch thick wedge) absorbers are also used giving better performance at near grazing incidences w.r.t. Pyramidal absorber. Special corner blocks were used corresponding to (C) type absorbers. Special open cell (10 pores per inch polyurethane foam based) absorbers with very high air permeability were used on conditioned air dispensers.
 
 
 
 
 
 
RF & Microwave Solutions
Product Range
  Shielded Anechoic Chamber
Modular Pan Type Enclosures
Welded Enclosures
MIL-STD/Commercial EMI/EMC Measurements
3M / 10 M Ranges
  PU Foam Based Microwave Absorbers
Pyramidal Absorbers
Walk on Absorbers
Flat Multilayered Absorbers
Wedge Absorbers
Convoluated Absorbers
Antenna Shroud Absorbers
  Shielded Anechoic Chambers
RCS Measurements
Antenna Pattern Measurements
Semi-Anechoic Chambers for EMI/EMC
  Rubber Absorbers
Thin Narrowband Resonating Absorber
Thin Dual/Broadband Flexible Absorber
Surface Current Attenuating Sheets
  Shielded Products
Conductive Rubber Sheers
 Anechoic Test Boxes
Solar Cell Mfg Machine
Gems & Jewellery
Engineering Solution
Automation & SPM
 
 
 
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