Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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EVLA Feed CDR
Outdoor Antenna Test Range
(OATR)
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Purpose
To support the EVLA Project by providing:
• A mechanism to monitor the feed horn manufacturing process by using:– VSWR measurements: All new feeds will be tested! (100% Sampling)
– Radiation patterns: Statistical Sampling = 5 or 6 units from each frequency band + the first feed fabricated
with new or modified manufacturing process.
(~20% Sampling)
• A long-term troubleshooting tool!
• Future design testing platform.
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Why a local facility?
$93,000 $148,510 $13,629 $4,100 $6,840
Antenna Range Costs Comparison
New Mexico Tech contributions to completing the
project:
Shipping/Testing Costs @ External Testing Facility
(Estimate)
Total Projected Costs for antenna range with brand new
equipment:
Total Material and Equipment costs for building test range
(to date):
Funds required to complete project:
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Progress (Highlights)
Overall Completion: 51%
Requirements: 60%
Location: 30%
Using double density polystyrene foam tower.
1700lb Vertical Load Capacity
Based on the optical encoder resolution with the systematic backlash of the positioner.
0.05deg Angular Resolution
To reduce potential multi-path reflection energy.
14ft Elevated Platforms
Simulating the distance between the sub-reflector and the feed circle.
22ft Baseline Separation
Refinement still in progress!
Amplitude Repeatability:
~ 1.5dB
Estimate only!
Based on acquired radiation pattern data.
Sensitivity:
-70dBm
Standard Gain Horn coverage
Actual Coverage:
1 – 18GHz
HP8510B (Rx)
HP8340A (Tx)
Tunable Frequency Range:
45MHz – 26.5GHz
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Capabilities (Generalized)
• Amplitude and Phase measurements.
• Time-Gating with pico-second resolution.
• Gain normalization.
• Phase Center measurements.
• Axial ratio / Polarization measurements.
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:The Site!
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Proof of Concept Setup
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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(Intentionally left blank)
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Progress (Detailed)
System Automation Manual Computer CompleteTunable Frequency 1 to 8 GHz 1 to 12 GHz min. Exceeded
Receiver Type Scalar (amp) Vector (amp & CompleteAmplitude Accuracy < 1 dB < 1 dB In Progress
Phase Accuracy n/a TBD In ProgressSensitivity (1 KHz < 60 dBm < 60 dBm In Progress
Source Output < +10 dBm < +10 dBm CompleteNominal Tx ~ 40 deg. ~ 40 deg. In Progress
Nominal Tx Gain >12 dBi >12 dBi CompleteRange Type Elevated (10 ft) Elevated (22 ft.) In Progress
Range Length (R) 22 ft (fixed) Up to 200 ft CompleteClutter Free Range > (3*R)^2 sq. ft > (3*R)^2 sq. ft In ProgressAUT Vertical Load 1000 lbs. 1000 lbs. Exceeded
AUT Moment 1000 ft. lbs. 1000 ft. lbs. CompleteAngular Accuracy < 0.1 deg. < 0.1 deg. Complete
GoalsRequirement
Stable output at various levelsNew Standar Gain Horns require further evaluation.
Computer Controlled45MHz to 26 GHz Possible
Vector (HP8510B)Initial results <2dBm with response calibration. Testing in progress.
Status Notes / CommentsMinimum
Requirement
Established Requirements and Progress
>1100lbs achieved with High Density Foam Column Tower. 1000lbs
0.05 deg with systematic backlash included.
11.5 to 23 dBi typical for Gain Horns.Elevated (14ft)
Established 22ft SeparationLocation depenant item.
Will be identified after permanent location establishedTesting in progress.
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Reflections
-70
-60
-50
-40
-30
-20
-10
0
-180 -157.5 -135 -112.5 -90 -67.5 -45 -22.5 0 22.5 45 67.5 90 112.5 135 157.5 180
1.0 GHz 1.75 GHz 2.35 GHz
-55
-50
-45
-40
-35
-30
-25
-20
-140 -135 -130 -125 -120
Without
-55
-50
-45
-40
-35
-30
-25
-20
-140 -135 -130 -125 -120
With FEDEX
64 Integrations No Time GateH-Plane Co-Pol
Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005
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The OATR:Boresight (Electrical)
Boresight Improvements
-0.5
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-4 -3 -2 -1 0 1 2 3 4
Peak of Beam Angle
64 Integrations / Time Gated
No Integrations / Time Gated (Worst Case)
64 Integrations / Time Gated / Curve Fitting
The amount of error from zero (both amplitude and peak of beam) is represented by the shaded rectangles.
The best boresight is being obtained by using a polynomial curve fitting which is represented by the solid rectangle!