Originally Posted by RSMacG
What I'm looking for is a more or less plug-and-play USB wifi "antenna" to boost the send/receive range of my on-board PC. Range and power are paramount. I won't be mounting anything permanently - ideally, I'll run a reasonably short (< 15ft) USB cable either out a porthole or up the companionway
and just sit (perhaps suction-cup) the antenna on the cabin
top. The antenna will need to be omnidirectional, as we may swing through a full 360 degrees.
I know technology is always a series of compromises, but for an omni-directional antenna mounted approximately 9ft above the water, what specifications are optimal? Should I be looking for a low-gain antenna? What is "low"? Wattage (more is better, or is it more complicated than that)?
You've asked some pointed questions, and here are some answers....
1) What you want (as others have posted) is not a wi-fi "antenna" but rather an external wi-fi modem
WITH its own antenna....
2) Although I'm partial to my own set-up, but would probably use a Bullet 2HP in the future.......for YOUR application (portable, not permanently mounted. plug-n-play USB unit), I'd recommend the new Alfa unit.....(see below for specifics)....and two antennas, one short one (~ 3db) for normal use, and one longer one (6-9db) for times when you may need longer range....
Total cost here, including a long USB cable and extra antenna, is going to less than $50.....
3) I spent over a year using, and experimenting with a couple different wi-fi set-ups (both on board and on shore)......and like Chuck, in the end I opted for a more robust and weather
proof "semi-permanent" solution.....
I wrote a long article about wi-fi, and my year long experiments, as well as detailed my entire set-up, with lots of photos.....
Please understand that while electronics
is my profession, I'm NOT an IT guy, and I did NOT delve into minute details of different systems, but kept my explanations in the layperson to "light technical" genre.....
4) As for what "specs" to look for.....
a) Use an antenna with 3db to 9db of gain.......(short 3db antennas are nice for ease of portability, and 8-9db gain antennas are the max that you'll find "usable" for portable and/or "hanging from a halyard" operation..)
b) USB-based Wi-Fi units are spec'd by their power output (current max is 2watts/2000mW, with typical units being 1/2watt/500mW to 1watt/1000mW)......
And their receiver sensitivity, based on speed/thru-put (meaning the slower the speed, the more "sensitive" the receiver operates...)
Here are a couple of examples:
Transmitter Output PowerManufacturer's specification is 2000mWReceive Sensitivity
Transmitter Output Power1000mWReceive Sensitivity
48Mbps (64QAM): -71dbm
36Mpbs (16QAM): -78dbm
24Mbps (16QAM): -80dbm
18Mbps (QPSK): -81dbm
12Mpbs (QPSK): -82dbm
9Mbps (BPSK): -85dbm
6Mbps (BPSK): -91dbm
c) Assuming that you don't want to spend a lot of $$$, please have a look on-line, for companies that specialize in low-cost and easy-use wi-fi networks and systems......you'll not find much at Best Buy, or computer stores.....
The guys I've found that are VERY knowledgeable and VERY honest, are the guys at Data-Alliance Data Alliance: Long-Distance Wireless Networking Equipment & Support
And, in addition to making sure that everything you're ordering will work together properly, they've got VERY low prices as well.....
(This point is important.....as some stuff you buy on-line is crap, and some of it just doesn't play well together.....trust me I learned the hard way!!!)
d) As for specific units, try the new Alfa unit......
Alfa AWUS036NH 2000mW Best Long Range USB Wireless Adapter. 802.11N/G/B. w/Jack & Antenna
Alfa AWUS036H 1000mW USB Wireless WiFi Adapter + Antenna. Long-Range. Upgrade from 500mW
(this is the one I'm using)
For more units, antennas, etc.....surf the data alliance website.....including their technical info section, etc. and you'll learn a lot...
I do hope this helps....
s/v Annie Laurie