August 17, 1995

UPDATE: Radio Neutrino Project

Since I lasted composed an update on August 8, much has changed. Perhaps the most significant is that the former name BANDA may not apply at all. That is, the biconical antenna design may not be the best design after all. A cylindrical dipole is now an equally likely possibility. I am, therefore, withdrawing the name BANDA which was never officially adopted. Until a more suitable name comes along, I will refer to my work as the Radio Neutrino Project.

During the past week:

- I spent much time contacting antenna engineers, Avi Hartenstein from Tecom Ind. (pg. 48 in lab journal), Stuart Kron from ARA (pg. 60), and Dr. Angelakos from EE Dept. at UCB (pg. 63). I learned about the 1/4 wave choke idea, and about the possibility of using ferrite cores to shield the cable.

- I began design on a 1/4 wave choke bicone, a very complicated design. I figured that, although a bit difficult to make (and far from ideal), it was a great deal cheaper for me to construct a prototype than to contract an antenna company to engineer and test a prototype. I was told it would cost $5000 for a prototype, which is more than I am being paid all summer, so I figured it was worth my time to explore this option.

- I spoke with several Pressure Vessel Companies. Although some were eager to help, it was decided that preparing our circuits to withstand the pressure ourselves would be more practical. I agree.

- I talked to AMANDA people. First with Doug Lowder on the phone, then I met with Dave Nygren, then I met Dr. P. Buford Price and Austin Richards. It was during the meeting with George, myself, Dr. Price, and Austin that much was decided about the fate of this project.

  1. For now, there is no possibility of actually putting an antenna on the AMANDA string. There is not enough room for them, and it is too risky for the Optical Modules. Plus there is no official time (man hours) to deploy or run any additional experiments.
  2. There is a slight chance that ONE antenna could be brought down in someone's luggage (with its own cable) and put into the ice. Then it could not be tested for a year or so, but at least it would be down in the ice... ready.
  3. As far as antenna design, since we are not on the main string anymore, we no longer have the problem of huge cables going through the antenna. The problem is that we now do not have a cylindrically symmetric setup, due to the wire now in the field pattern. Must thoroughly test these effects. These issues were brought up about the antenna:

    1. No longer need a choke to shield from inner cable.
    2. Austin said must be very strong and hydrodynamic. He said that our present designs would be ripped apart during actual deployment. Must be much more durable. Also, water must flow through in the most efficient ways. Must be lightweight though.
    3. So we no longer need a large hole in our antenna, but it still seems to our advantage to keep circuitry inside cylinder. So, the clearance needed for circuitry is only factor in cylinder diameter.
    4. We need a way to keep it from the other wires (as far as possible) and make sure that it doesnŐt interfere with the AMANDA project. Plastic is a possibility, but Lucite is no good under that those pressure conditions.
    5. The work done at the Pole must be negligable. No assembly required. No rivet guns, no screws, only clamps which are part of the device itself.

- I went ahead and finished the 1/4 wave choke bicone to test. But it will most likely not be used.

- I ran the reflectance test on all three antennas that I have made now and printed the data (pg. 69-71 in lab journal).

- I have come up with a proposed design for the antenna which I will now draft up on MiniCad+ and show to George. Discussing it with him. I will attach a copy to this document.

from Update 8-8-95: (edited)

I still need to:

- Look into this problem of the AMANDA cable interfering with our field patterns.

- Finalize the antennaŐs dimensions, according to the central frequency we desire. I must not forget to take into account the refractive index of ice, 1.78.

- Discuss the circuitry/amplification with those more knowledgable. Decide on how all this will mount inside the antenna and how it will withstand the pressure.

- Run the necessary tests here to verify the functionability of the completed antenna.

- Consider what procedures to be performed once in Antarctica. Document them.

- Get information on Radio Neutrino Project onto a World Wide Web page.

There is a great deal of work to be done. I hope to complete this project by September 1, 1995, my date of departure. I am documenting my progress however, so that those who follow-up my work will know what I have done.

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