[time-nuts] The Demise of LORAN (was Re: Reference oscillatoraccuracy)

Magnus Danielson magnus at rubidium.dyndns.org
Sun Nov 15 21:58:05 UTC 2009


Robert Atkinson wrote:
> There is also the use of directional antennas. Difficult to put your jammer between the Rx and the sat. 

Actually, that doesn't help much in a multiple jammer scenario.

The directional antenna needs to have their directional lobes towards 
each sat being tracked. If you try put the nulls towards the jammers 
then you need to have a fair knowledge of where it is. If you direct the 
loop, the side-loobs needs to be sufficiently suppressed. A single 
jammer and a fair idea of the heading will work, but it becomes complex 
and in the end you need more and more antennas to handle more jammers.

Also, recall that you need good dynamics on all the antenna frontends.

You can handle it, but it isn't compact and neat as you are used to.

Directional antennas gives some additional gain, but to a limit. It 
comes at a price. A rather high price compared to many other 
countermeasures. It only fit some few uses.

Cheers,
Magnus




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