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From: David Jefferies
Date: 28 Mar 2002
Time: 13:56:52
Remote Name: 195.92.194.12
Bill,
We have two experiments running. In one of them, a 2GHz dipole has polythene-like cylindrical sleeves fitted over the rods. There are a number of these sleeves of differing diameters. They don't have to be pushed all the way on.
I haven't looked at this closely enough to comment as the student should not be interfered with when doing the project. I shall get round to playing with the bits myself later on.
The measurements show strong VSWR dips at three frequencies. Tracking these as a function of sleeve thickness shows no experimetally significant trend, but I haven't watched to see how the data is taken, just looked at the results.
In the other experiment, a thin wire ADR is sandwiched between two 5mm thick sheets of "polythene" whose dielectric constant hasn't been measured yet. This project is at an earlier stage; bringing the sheets of plastic up to the frame of the ADR does not much perturb the plot on the network analyser. Again, I haven't seen this and shall go and have a play later on.
These student projects have the intention of "educating the student" rather than "doing the project", and to be a level playing field it must be the student that plans and executes the project, across the cohort of 200 projects in the School. Thus, I am loth to go along and interfere at this stage.
David.