Home |
Search |
Today's Posts |
#9
|
|||
|
|||
"Ionic Liquid" Antenna
K1TTT wrote:
On Sep 6, 11:41 pm, Art Unwin wrote: On Sep 6, 2:00 pm, Roy Lewallen wrote: On 9/6/2010 8:59 AM, K1TTT wrote: magnetic coupling to the stream seems kind of odd, but it appears to work for him. i wonder what happens if you go qro? i would expect some heating of the water and maybe even some ionization or corona that might cause instability in the stream. i would also guess the tuning would be difficult in high winds. Wind would seem to be a weak point. The top of the conductive stream would dissipate at different heights depending on the wind velocity, so a gusty wind would be constantly altering the effective antenna length. Roy Lewallen, W7EL Part of the speal given talked about the scarecity of real estate for the many antennas on ships! Why don't they use non frequency dependent antennas so antennas can be shared, especially when in combat? And what do submarines use for antennas when in the stealth mode? i would tell you, but then i would have to kill you! Naahhh.. everyone knows they drag an insulated wire, which is why NEC was updated some years ago to handle insulated wires in a conductive medium. Now.. when their periscope is up, indeed, there's a lot of special stuff that goes into shared apertures. Look to the work of Jaumann in WWII.. And with sharing apertures.. it's not so much non-frequency dependent radiators that is the problem, it's isolation between the Tx and Rx. Multimegawatt pulses from your radar tend to raise cain with your sensitive receiver, even if your diplexer does have 100dB isolation. Finally, it is challenging to make something that can efficiently radiate at a frequency while not reflecting that same frequency (i.e. re-radiating). Brings a whole new meaning to "match at the feedpoint" when your RCS has to be a tiny, tiny fraction of the physical size. (for reference, the RCS of a resonant dipole with shorted feed is about 0.2 lambda^2) |
Thread Tools | Search this Thread |
Display Modes | |
|
|