Troy A. Jensen EVLA Feed CDR - OATR17 Feb 2005

1

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

4

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!