[time-nuts] "Better" gps antennas than a Symmetricom 58532A

Chris Albertson albertson.chris at gmail.com
Wed Jan 23 17:23:11 UTC 2013


The Thunderbolt book suggests using RG6 (75 ohm) up to some given
length and then other cable like RG8if the length is longer.   I can't
look it up right now.   They claim the rg6 is very good because of the
double shield.  Trimble claims the 75 v. 50 mismatch is trivial.

On Wed, Jan 23, 2013 at 12:41 AM, Hal Murray <hmurray at megapathdsl.net> wrote:
>
> mspencer12345 at yahoo.ca said:
>> This URL goes into some of the issues involved in using 75 ohm coax in a gps
>> system.  I do acknowledge that several GPS manufacturers have promoted the
>> use of 75 ohm coax so some of the conclusions might be arguable..
>
> If the coax is short, the loss due to mismatch dominates.  If the coax is
> long, the attenuation per X meters will dominate.
>
> There should be a crossover length  What is it for 50 ohm RG-58 and 75 ohm
> RG-6?
>
>
> If you are designing your own antenna, you have the option of making one that
> matches 75 ohm rather than 50.
>
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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-- 

Chris Albertson
Redondo Beach, California



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