1. X-Y Planar Precision Scanner
Antenna and Optical Beam Measurement Facility for JEM/SMILES
Antenna Optics : Cassegrain with Elliptical Beam
Mission Requirements : GHz – GHz,
HPBW : 0.174deg (Az), 0.083deg (El)
Beam Efficiency higher than 90%
Purpose of Measurements : Far-Field Pattern, Beam Width,
1’st Sidelobe Levels,
Measurements : Near-Field Phase Retrieval Method (NFPRM)
NASDA NFBM System
Sample Images of
Measurement Result
X-Y Planar Precision Scanner
Prototype Model of
Main Reflector
Estimated Far-Field Pattern of Antenna
Rear View
X Stage
Z Stage
Ambient Temperature Optics
NASDA Submillimeter Transmitter and Receiver System
Estimated Far-Field Pattern of Horn
Front View Rx
Optical Chopper
Submillimeter Optics :
Beam Wave Guide (BWG) System,
Frequency-Selective Polarizer (FSP)
with Wire Grid
Mission Requirements :
Sideband Separation (USB/LSB),
Low Loss Beam Transfer,
Lo Injection, Image Termination
Purpose of Measurements :
Transfer Beam Characteristics,
Alignments (Goal)
Measurements :
Near-Field Beam Measurements (NFBM)
To Antenna
To Cold-Sky
Terminator
Single Sideband
Filter
Sub-mm
LO Source Tx

2. Near-Field Phase Retrieval Algorithm
Initial Estimate
of Complex
Aperture
Function
with Random
Phase
Estimated
Far-Field
Measurement
Plane #1
Measurement
Plane #2
Antenna Aperture
Plane
First
Itaration
only
Diffraction Filters FT
FT-1 X Z
Far-Field
Z=Z0
Fresnel-Region
Z=Z1
Z=Z2 Y