SKA Dishes, SEEG Meeting Cape Town September 2013 SKA Dish Verification Antenna #1 – Test Plan Gary Hovey, DVA-1 Project Manger Astronomy Technology Program – Penticton SEEG Meeting, Cape Town 19 September 2013

SKA Dishes, SEEG Meeting Cape Town September 2013 Unit/Sub-assembly Tests Assembly/Integration Tests Qualification Tests Single-dish Tests Outline Specification for the DVA-1 Dish (WP RS-001) DVA-1 Test Requirements for the SKA (WP TN-001) DVA1 Test Plan Overview 2 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Verify components are properly manufactured Measure performance of units and system. Compare with Requirements Check readiness for a subsequent test phase. Key performance aspects of DVA1 to be confirmed: –Shape of composite surface(s) –Performance of RIM-supported structure –Performance of foundation and light-weight mount –Performance of Shaped offset-Gregorian-feed-high optics DVA1 Test Plan Test Objectives 3 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Transitory (Pretty much only one shot at it.) Chance to understand performance of individual pieces. Primarily metrology based (Laser tracker / Photogrammetry) Load/no load tests. Key components –Foundation –Mount –Power –Drives –Reflector surfaces DVA1 Test Plan Unit/sub-Assembly Tests 4 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Tests –Deflections under load –Check for stability and evidence of rocking Equipment required –Laser tracker –Hiab crane –Test load DVA1 Test Plan Foundation 5 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Control via pendent Tests –Safety logic responds as planned –Fail-safe brake and E-stop –Speed and range of motion –No load power usage Pre-requisites –AC Power –Cabinet DVA1 Test Plan Basic Drive System 6 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Tests –Electrical Power lockouts –E-stop and limits switches –Range of motion –Tower deflection vs moment –Motor torque vs speed –Encoder linearity Equipment needed –Basic drive system –Laser tracker –Hiab crane –Tilt meters & Data logger DVA1 Test Plan Mount 7 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Measure surface –Static shape –Shape changes with temperature (and perhaps load) Equipment –Laser tracker –Photogrammetry Other tests –RF reflectivity –Material coupon tests DVA1 Test Plan Reflectors 8 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Initial Tests –Safety logic and fail safe brake –Basic motion –Range of motion –Full drive operation Tracking Slewing logging Host computer control These will be done initially without the feed support and sub-reflector. DVA1 Test Plan Initial Qualification Tests 9 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Measure changes in shape and position over gravity, temperature, wind, and time –Pedestal –Primary and sub-reflectors –Feed support DVA1 Test Plan Mechanical Performance Tests 10 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Ku band receiver tests –Adjust feed –Check receiver and backend –Check pointing DVA1 Test Plan RF Qualification Tests 11 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Holography Pointing modeling –Tracking precision repeatability testing Tipping curves Antenna radiation patterns and efficiency System power and dynamic effects over environment. DVA1 Test Plan Single Dish Testing 12 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Pointing Model The pointing model will continue to be refined and updated. Any evolution of the pointing model will be noted and analyzed. We are considering using an optical telescope securely mounted in the focal region to use for optical pointing. This is more accurate and can look at dynamic effects. A source will be tracked at the 3dB point for more accurate measurement of the RF pointing Tipping curves Tipping curves will be measured to determine the effect of ground spillover as a function of elevation (and azimuth, depending on the horizon variability). This is a direct measurement of the spillover, and can be useful in looking at various baffle structures. Note that the standard “signal” for tipping curves (the atmosphere) will be removed to leave the residual ground-coupling. DVA1 Test Plan Single Dish Testing 13 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 DVA1 Test Plan14 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Holography With the inclusion of a small reference antenna and a prepackaged microwave holography system. Antenna patterns/efficiency Wide-angle pattern cuts will be measured (primarily using satellites) to measure beam-shape and side-lobe structure etc. This will be done at different frequencies (as available) and in the presence of varying solar insolation, wind and elevation. Power consumption Drive system can relay motor power and torque, as well as tilt and gear train torque to host computer. DVA1 Test Plan Single Dish Testing 15 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Polarization Polarization will be investigated by looking at: –highly polarized satellite downlinks and mapping dual-linear polarization patterns –natural sources with reference antenna –Both use a reference antenna + correlator –Mechanically rotate by 90o DVA1 Test Plan Single Dish Testing 16 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Antenna designed for wide-angle UWB feeds Could reduce the canonical “5-feed” arrangement to 1,2 or 3 Modeling shows ground-spillover limits Ae/Tsys –Is there a baffle arrangement to mitigate? Multiple versions: –ATA, QSC, Quad-ridge, 11 feed, … Might make most sense at low frequencies: – , ( ), 5-10 – , ( ), 3-6 DVA1 Test Plan Wide-band Feed Testing 17 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Outside scope (for N>2) Outlined in“DVA-1 Test Requirements for the SKA” WP TN-001. Use to characterize beam with multiple reference antennas (closure relations) Internet based VLBI? Leave in hooks as possible to use with ST DVA1 Test Plan Interferometric Testing 18 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Sources: Satellites Ku-band: e.g. DirecTV, DISH S-band: e.g. XM radio, Sirius C-band: e.g. Anik, ABS L-band: GPS, iridium DVA1 Test Plan19 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 We have a holography receiver. Lynn Baker has designed a Ku band holography feed and is designing an L-band feed. Need receivers for other bands MeerKat receiver would be useful for L-band testing. DVA1 Test Plan Receivers Backend 20 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Sep 25 Mount arrives Oct 25Begin foundation/mount/drive testing Nov4Back-structure attached to Reflector Nov 6Begin reflector unit testing Nov 13Install reflector on mount Nov18Begin Qualification testing Dec 3Secondary and feed support Installed Dec 20Non RF testing mainly complete Key reflector and mount performance characteristics known DVA1 Test Plan Schedule/Milestones (Pre-single dish tests) 21 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Jan 6 Begin RF qualification testing Jan 20Being Holography testing Feb 3Install and qualify L-band feed (MeerKat) Feb 17Begin pointing modeling Mar 10Begin measuring tipping curves Mar 24Measure antenna pattern and efficiency Apr 14Investigate polarization performance May 2014 Initial DVA1 single dish testing complete Summer 2014Testing of other bands DVA1 Test Plan Schedule/Milestones: RF Single Dish Testing 22 of 23

SKA Dishes, SEEG Meeting Cape Town September 2013 Questions? Comments? DVA1 Test Plan23 of 23