[email protected] said: > I have a Sure Electronics GPS board and I want to extend the antenna cable > several feet. Is anybody able to confirm the RG cable type and coax > connector of the antenna? My assumption is it's a RG-58 cable with a SMA > connector.
It's probably easier to extend the RS-232 cable. :) ---------- There are 2 issues with coax. One is loss due to skin effect and dielectric absorbtion, measured in dB/meter. It's frequency dependent. GPS L1 is 1.4 GHz. Most coax is generally not great at that frequency. The other is loss due to impedance mismatch. Most lab setups use 50 ohm coax. Cable TV uses 75 ohms. In general, bigger coax is lower loss, and for the same outside diameter, 75 ohm coax is lower loss than 50 ohms. Most decent coax uses foam-polyethylene for the dielectric. The air in the coax is close to zero dielectric loss. Most GPS antennas and receivers are setup for 50 ohms. Trimble points out that the loss due to impedance mismatch is low compared to not-many feet of readily available coax, so RG-6 works better than you might expect. They ship RG-6 in their evaluation kit. ----------- The thin cable on the Sure antenna is probably RG-174. RG-174 is 50 ohms. It's 1/10 inch dia, high loss. (but flexible and inexpensive) RG-58 is 50 ohms. It's about 1/4 inch in diameter. This is standard lab coax. RG-59 is 75 ohms with roughly the same diameter as RG-58. RG-6 is 75 ohms. It's slightly bigger and significantly lower loss. It's widely available as low-loss cable TV coax. LMR-400 is about 1/2 inch in diameter. It's 50 ohms, low loss, and expensive. Lots of good info here: http://en.wikipedia.org/wiki/Coaxial_cable -- These are my opinions. I hate spam. _______________________________________________ pool mailing list [email protected] http://lists.ntp.org/listinfo/pool
