Can I Use A Longer Cable With My Antenna/Amp? |
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Wednesday, 19 October 2011 |
Mobile Broadband FAQ #13: Can I Use A Longer Cable With My Antenna/Amp?
 The mobile broadband experts at 3Gstore/EVDOinfo answer countless questions from our customers and from the EVDO Forums community
every day - from general mobile broadband questions ("what the heck
does 3G mean?") to specific questions about products to more advanced
inquiries about what one can do with their mobile broadband service. The
"mobile broadband FAQ" series addresses these questions in depth one
FAQ at a time. To view ALL of the FAQs we've addressed in this series,
visit EVDOinfo.com/faq.
Can I Use A Longer Cable With My Antenna/Amp?
A
common question that customers ask us when discussing antenna options
is "how much cable can I use?", and the answer is - Yes, you can use a
longer cable but it will affect the overall performance (signal gain).
The longer the cable length, the more signal loss you'll have through
the cable - If you have to much cable, you'll completely defeat the
purpose of the antenna. This is why we always suggest using as short a
cable length as possible to preserve as much signal strength as
possible.
We offer antenna's for a wide variety of applications
and they come with different style cable grades and lengths. These cable
grades all have different "signal attenuation"
ratings which determine how much loss you'll have through the cable. As
you increase the cable length, you'll want to increase the cable grade
(RG58, LMR240 & LMR400) to preserve as much signal from the antenna
to your wireless modem. If you don't increase the cable grade with
longer runs, you'll negate the performance of the antenna by losing the
antenna gain through the cable.
Cable Grades:
- RG58 - Recommended for short cable runs less than 15ft: IE - 10ft RG58 cable creates attenuation loss of 2.6-4.4dBm
- LMR240 - Recommended for medium cable runs less than 25ft: IE - 25ft LMR240 cable attenuation loss of 1.8-2.8dBm
- LMR400 - Recommended for long cable runs more than 25ft: IE - 30ft LMR400 cable attenuation loss of 1.1-1.7dBm
As
you can see, even though the 30ft LMR400 cable is three times the
length of the 10ft RG58 cable, the signal attenuation (signal loss from
external antenna to end of cable inside your home) is less than half of
what a shorter RG58 cable is. Full reference chart below:
Antennas like the Wilson Trucker and 21" Omni RV antenna
come with short run RG58 cables (12-13.5ft) and are great for users
that don't require long lengths. The cable on those models aren't
detachable though, meaning the only way to use more cable with these
options are to add an extension cable. Daisy chaining these cables
(linking cables together) isn't recommended because you induce more
cable loss from the connectors and the additional cable length. If you
feel you need a longer cable run, an option like the Building Mount Omni
includes 25' of cabling. The main benefit of an antenna like this is
being able to replace the 25' included cable rather than being forced to
daisy chain cables together. This means you'll be able to go with a
single run of cable and preserve as much signal through the antenna as
possible.
If you've already purchased an antenna and don't have
the ability to detach the cable you can get a cable extender. Just be
aware that you'll be degrading your signal in the process which may be
an issue if the signal is already really poor at your location. If you
must add another cable, we suggest adding our 3 Watt amplifier
which will allow you amplify the signal negating the loss that the
cable creates. When placing an order for an antenna, be sure to have a
good idea of the amount of cable you'll need and try not to use anymore
cable than absolutely necessary.
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Last Updated ( Tuesday, 09 October 2012 )
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