[time-nuts] Lucent 40 dB Antenna

Charles P. Steinmetz charles_steinmetz at lavabit.com
Wed Apr 11 12:20:42 UTC 2012


Chris wrote:

>Where are you placing your antenna?  I'm curious because you say the
>choke ring helps.  Is it close to the ground, near a building?  What
>might be the cause of the muiltipath that the choke ring is helping
>with

I've been working with RF long enough not to expect easy answers when 
it comes to multipath.  It's pretty much always there, sometimes in 
sufficient quantity to be really troublesome, other times (as with 
GPS at my location) enough to notice but not to be really troublesome.

Typical suburban neighborhood, 2-story brick houses on ~80-foot 
lots.  The antennas have been tried (i) on the second floor (under a 
plaster ceiling + asphalt shingle roof); (ii) in the attic (under the 
roof only); and (iii) on a mast about 15' above the roof peak (~45' 
AGL).  The c/n improves ~ 7 dB going from (i) to (ii) and another ~2 
dB going from (ii) to (iii) for all antennas, while the relative 
advantage in positioning and deviation of the choke ring is 
essentially unchanged.  After experimenting, I installed the choke 
ring antenna in the attic peak.

A ground plane placed under the mag mount and the Bullet 3 did not 
improve the positioning or deviation.

Best regards,

Charles









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