the kat 7 feed package
Download
Skip this Video
Download Presentation
The KAT-7 feed package

Loading in 2 Seconds...

play fullscreen
1 / 18

The KAT-7 feed package - PowerPoint PPT Presentation


  • 116 Views
  • Uploaded on

The KAT-7 feed package. 1. EMSS ?. A group of companies, operating from Stellenbosch, SA Employee-owned, 100 bodies, T/O ~ $M6 CEM code FEKO: www.feko.info EMSS Antennas (8 bodies) Contracted into MeerKAT project, cost-plus-material basis, shared risk

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' The KAT-7 feed package' - santos


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide2
EMSS ?
  • A group of companies, operating from Stellenbosch, SA
  • Employee-owned, 100 bodies, T/O ~ $M6
  • CEM code FEKO: www.feko.info
  • EMSS Antennas (8 bodies)
    • Contracted into MeerKAT project, cost-plus-material basis, shared risk
    • Self-representative on subsystem level
    • Develop and implement feed technology, act as custodians of EM issues

2

the kat 7 reflector revisited
The KAT-7 reflector: Revisited
  • Design freeze late 2007
    • D = 12m (project decision, based onSKA trends)
    • F/D = 0.38 (Calculated to suit typicalWBFs, also allowing a classicalhorn feed as fall-back)
    • Prime focus: Four struts, (+),~2/3 out, cross-section shaped tominimise spillover
    • Surface to be flame-sprayedAluminium or mesh, 1.5mm RMS
    • Drives: Elevation over azimuth

3

the kat 7 horn design freeze early 2008
The KAT-7 horn: Design freeze early 2008
  • Design briefs
    • 1200 – 1950MHz (48%)
    • Orthogonal linear polarisations
    • Optimise Ae / (Tspillover + X)
  • Results
    • Choked wide-angle horn, Ø = 1m (oversized)
    • Irises (for impedance matching af flower)
    • Theoretical TE11 mismatch: ≤ –33dB
    • Theoretical Tspillover: 5  2K
    • Theoretical illumination efficiency: 70  65%

5

the kat 7 omt
The KAT-7 OMT
  • Design briefs (early 2008)
    • Smaller than typical bladed OMTs (to facilitatte small cryostat)
    • High-fidelity, no hybrid devices
  • Chosen candidate
    • Two crossed dipoles in shorted waveguide
    • Impedance-transforming feeder lines
    • Two Marchand baluns
    • Design method: Aggressive space mapping

9

the kat 7 omt size
The KAT-7 OMT size
  • Size does matter…
    • Final device quite small
    • 0.2λ3
    • Thus small cryostat areal possibility
    • Theoretical performancevery promising
    • (Typical quadridgestructures = 3 – 6 λ3)

10

the kat 7 horn pattern measurements
The Kat-7 horn: Pattern measurements
  • Pattern verification
    • 500m Ground-reflection far-field range
    • Principal planes and diagonal cuts made
    • Fed by prototype single-mode transducer
    • Found excllent agreement with CEM predictions

12

the kat 7 horn omt port properties1
The KAT-7 horn + OMT: Port properties
  • Loss?
    • Crude method: Short waveguide, divide insertion loss by two
    • Looks like 0.1+ dB
    • I.e., ~8K at ambient,and ~2K at 77Kphysical
    • Since verified by twoOMTs back to back,transmission –0.2dB,confirming 0.1dB loss

15

the kat 7 cryostat
The KAT-7 cryostat
  • Design briefs
    • Small vessel, robust
    • Stirling-cycle cryo-cooler
      • Sunpower GT unit: 15W at 77K (neck at 30°C)
      • Cold fluid up from pedestal, for cooling the cooler
    • No mechanical vacuum maintenance
      • Ion pump, carbon traps, limited cryo-pumping at 77K
    • Host to LNAs and noise injection circuitry
    • Life support from pedestal below

16

conclusions
Conclusions
  • Good horn performance from prime focus
  • Very good performance from small OMT
  • Getting there with a small robust cryostat
  • Full development will be captured in a project memo, towards end of 2009
  • Thank you.

18

ad