Antennas Feeds Mechanical Design Feed Cone Feed Mounting

Antennas & Feeds Mechanical Design Feed Cone Feed Mounting Horn Fabrication Jim Ruff Antennas & Feeds PDR 2/12/02 1

Feed Cone • Why? – More Frequencies – RFI Containment – Reduced clutter at antenna vertex • How? – Similar to existing K/Q segments – Monolithic Jim Ruff Antennas & Feeds PDR 2/12/02 2

Feed Circle Jim Ruff Antennas & Feeds PDR 2/12/02 3

EVLA Feed Cone The L-Band horn is not contained in the feed cone. Jim Ruff Antennas & Feeds PDR 2/12/02 4

Feed Cone Jim Ruff Antennas & Feeds PDR 2/12/02 5

Feed Cone • Unresolved Questions – Aluminum or Polycarbonate core? • Aluminum cores are stiffer • Polycarbonate cores are better thermally – Service Access • Receiver heights vary greatly • Space will be at a premium Jim Ruff Antennas & Feeds PDR 2/12/02 6

Feed Mounting • Features: – Based on VLA X-Band – Continuous metal-to-metal for RFI containment – Simple horn installation and alignment – Convenient receiver swapping • Which Bands? – S? C X Ku K? Ka? Q? Jim Ruff Antennas & Feeds PDR 2/12/02 7

Jim Ruff Antennas & Feeds PDR 2/12/02 8

Feed Mounting Jim Ruff Antennas & Feeds PDR 2/12/02 9

Feed Mounting Jim Ruff Antennas & Feeds PDR 2/12/02 10

Feed Mounting Jim Ruff Antennas & Feeds PDR 2/12/02 11

Horn Fabrication • Laminated Horns (L, S and C) – Similar to VLBA L-Band horns – Reduce weight and simplify construction – Tooling Jim Ruff Antennas & Feeds PDR 2/12/02 12

Laminated Horns Jim Ruff Antennas & Feeds PDR 2/12/02 13

Laminated Horns Jim Ruff Antennas & Feeds PDR 2/12/02 14

Ring Loaded Horns • A Proposal for Ring Loaded Horns – Simplify assembly – Simplify receiver mounting – Improve flange mate-up reliability – Reduce manufacturing cost Jim Ruff Antennas & Feeds PDR 2/12/02 15

Ring Loaded Horns Jim Ruff Antennas & Feeds PDR 2/12/02 16