Nyquist Sampling at K band

  • \text{Magnification is 3, giving f/D of 3 x 0.6 = 1.9.}
  • \text{ Nyquist sampling (Voltage) of focal plane FWHM spacing required f} \frac{\lambda}{D}
  • \text{Feed spacing   required f   } \frac{\lambda}{D} =  2.44 cm
  • \text{Useable focal plane diameter is  0.5 meters (GBT memo 199).}
  • \text{Maximum number of feeds square packing:}   (\frac{0.5}{0.0258})^2 =  419 (20x20)

Airy Pattern K band:First null Diameter

  • \eta = 0.83\text{ Feed Diameter required 2.44  f } \frac{\lambda}{D}
  • \text{Feed Diameter: nominal 2.44 f   } \frac{ \lambda_0 }{D} =  5.95 cm

KPAF Horn Design Consideration

Single Horn

  • \lambda_0 = 1.27 cm
  • Pyramidal Horn
  • Horn Aperture: \lambda_0 \frac{f }{D} *\lambda_0 \frac{f }{D}* 6 \lambda_0
    • \eta = 0.79 @ \lambda_0
    • Requires four feeds to cover Airy Pattern
    • 16x16 array ~ 225 beams @ \eta = 0.79 @ \lambda_0

Dual Horn

  • Difficult to obtain proper match in the E plane, compared to a reasonable match in the H plane

  • Dual Horn: H sectoral rectangular horn with Length: \text{ 5}  \lambda_0
  • DualEsecHorn2.png

Commercial MMIC at K band

  • cmd163_ver_2.3_0516Kband.pdf: F = 1.3 dB, Te= 290(F-1) = 102 K; @ 15 K: ~ 102/10 = 10.2 K comparable to Cryo3 devices. 120 mA of current probably too high.
  • cmd160_ver_3.5_0516.pdf: F = 1.4 dB, Te= 290(F-1) = 110 K; @ 15 K: ~ 110/10 = 11.0 K comparable to Cryo3 devices. 26 mA but gain rolls off but still > 20 dB at 26.5 GHz. Two 1020 could cool ~ 300 devices.
  • Getting two samples to test July 7, 2016.

IF system

  • The KFPA IF system IDM1_block_diagram.pdf as an example.
    • Note: This module is dual polarization, only one polarization is required for this design.
    • Note: This module has a waveguide input, a coaxial input may be required instead.
    • Note: The Kband Phased Array Feed IF System requires a much smaller bandwidth, 400 MHz, and an output frequency range of 400 to 800 MHz.
    • The rejection level and input power level must be specified, which will determine the filter specifications and the total module gain required.
  • WVU CAPSTONE Project
  • cmd163_ver_2.3_0516Kband.pdf: Possible input amplifier
  • cmd160_ver_3.5_0516.pdf: Possible input amplifier

Backend Notes from Kevin Bandura

Previous AST/ATI Funding

Some Notes from the Old KFPA Internal NRAO Proposal

The old KFPA internal proposal is here: KFPA Proposal. The proposed, total cost in 2007 dollars, was $1.7M. Steve may have an estimate of the actual cost.

The old proposal was based around the capabilities of the GBT spectrometer, but it was noted that the GBT spectrometer provided a reasonable match to the required capabilities. A useful, if somewhat dated overview of ammonia is available in this AARA review paper. The principal lines are NH3 (1,1), (2,2) and (3,3) at 23.6945, 23.7226 and 23.8701 GHz (separation 176 MHz). Many o

The configurations discussed in the old proposal were:
  • 50 MHz total width and 16384 channels, giving, at 22 GHZ, a total velocity coverage of 680 km/s at a channel spacing of 0.04 km/s. This is a good match to surveys in the Galactic plane and allows in-band frequency switching as well.
  • 12.5 Mhz bandwidth and 16384 channels which gives, at 22 GHz, a total velocity coverage of 170 km/s at 0.01 km/s channel spacing. This is likely to be the main mode for study of individual molecular clouds.
  • 200 MHz total bandwidth with 8k channels or 800 MHz total bandwidth with 2k channels. At 22 GHz these modes give 2700 km/s at 1.3 km/s channel spacing, and 11,000 km/s at 5.3 km/s channel spacing, respectively. The broad band modes are well matched to observations of extragalactic molecular clouds, galactic nucleii, and high-redshift molecular lines.

Topic attachments
I Attachment Action Size Date Who Comment
AST_Awards.pdfpdf AST_Awards.pdf manage 56.0 K 2016-07-07 - 07:08 RichardPrestage AST ATI/MRI Awards 2012 onwards
DualEplaneFF23p4.bmpbmp DualEplaneFF23p4.bmp manage 3224.4 K 2016-06-23 - 08:48 StevenWhite  
DualEplaneS11.bmpbmp DualEplaneS11.bmp manage 3224.4 K 2016-06-23 - 08:49 StevenWhite  
DualEsecHorn2.pngpng DualEsecHorn2.png manage 91.6 K 2016-06-23 - 08:49 StevenWhite  
DualHplaneFF23p4.bmpbmp DualHplaneFF23p4.bmp manage 3224.4 K 2016-06-23 - 08:49 StevenWhite  
DualHplaneS11.bmpbmp DualHplaneS11.bmp manage 3224.4 K 2016-06-23 - 08:50 StevenWhite  
IDM1_block_diagram.pdfpdf IDM1_block_diagram.pdf manage 113.1 K 2016-09-01 - 14:30 StevenWhite  
Pymodel.pngpng Pymodel.png manage 135.9 K 2016-10-06 - 14:23 StevenWhite  
Pyrmidal22FF.pngpng Pyrmidal22FF.png manage 90.4 K 2016-10-06 - 14:29 StevenWhite  
Pyrmidal23p4FFE.pdfpdf Pyrmidal23p4FFE.pdf manage 74.3 K 2016-10-06 - 14:39 StevenWhite  
Pyrmidal23p4FFH.pdfpdf Pyrmidal23p4FFH.pdf manage 68.0 K 2016-10-06 - 14:39 StevenWhite  
PyrmidalS11.pdfpdf PyrmidalS11.pdf manage 74.0 K 2016-10-06 - 14:39 StevenWhite  
SingleHsectoralHorn18ff.bmpbmp SingleHsectoralHorn18ff.bmp manage 3212.7 K 2016-06-23 - 15:24 StevenWhite  
SingleHsectoralHorn23p4ff.bmpbmp SingleHsectoralHorn23p4ff.bmp manage 3212.7 K 2016-06-23 - 15:24 StevenWhite  
SingleHsectoralHornS11.bmpbmp SingleHsectoralHornS11.bmp manage 3212.7 K 2016-06-23 - 15:24 StevenWhite  
WVUNRAO_2016August17_MIF.pdfpdf WVUNRAO_2016August17_MIF.pdf manage 288.0 K 2016-09-01 - 14:34 StevenWhite  
cmd160_ver_3.5_0516.pdfpdf cmd160_ver_3.5_0516.pdf manage 203.4 K 2016-07-07 - 14:01 StevenWhite  
cmd163_ver_2.3_0516Kband.pdfpdf cmd163_ver_2.3_0516Kband.pdf manage 221.1 K 2016-06-23 - 09:00 StevenWhite  
kband_paf_meeting_notes_RFOF_digital_backend.pdfpdf kband_paf_meeting_notes_RFOF_digital_backend.pdf manage 106.1 K 2016-07-07 - 05:12 RichardPrestage Backend Notes by Kevin Bandura
Topic revision: r12 - 2016-10-14, StevenWhite
 

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