External Cellular Antenna - Line Loss

[JLR]

I have recently installed a wifi hot spot (cradlepoint mbr 1200B) and a CCTV system with remote access. Both systems are entirely dependent on the cellular signal I receive through an AT&T USB Lightning Aircard (3G) with a static IP address. I have had success in the past using an external cellular antenna connected to the aircard. However, the cable run between the two was no more than 10 feet. My local electronics fellow is not sure whether this aircard will suffer if connected to an external cellular antenna (already installed) with about 25 feet of cable. Hence, the line loss question. Although I already have some sort of Wilson amplifier of unknown vintage and power, I anticipate taking that out of the cabling and simply connecting the cell antenna on the top of my tower to the aircard. Do any of you folks know whether the aircard can power this 25' cable run or will line loss eat up any benefit I might get. By the way, I do not want to open up the discussion about boosters and amplifiers at this time so please let's put that discussion on hold for another day.

[GJH]

For that length you need to use LMR 240 or better yet LMR400 cable or the loss with standard RG58will negate the benefit of the antenna. My old company still does a lot of business in the cell signal boosting and antenna field.

[JLR]

Thanks George. Are those cables fairly readily available?

[34Hatt]

Thanks George. Are those cables fairly readily available?

http://3gstore.com/product/1695_wils...e-50-foot.html

[GJH]

Yes they are, as the example link shows. The key is having the proper connectors added to each end, as indicate for example by the text in the link. You want that done for you, it requires special tools to do right. I always like the quality of Digital Antenna's stuff the best, but Wilson is OK.

[JLR]

I just spoke again with my local electronics installer. He advises against either using a booster or a cellular antenna if my signal is presently adequate to get to the closest tower. He said, under those conditions, the booster or antenna will not increase the speed of my connection and have no affect on the transfer rate of my CCTV images. First, he said he has had problems with the boosters overwhelming other local cell phone users and that the boosters are designed to be used offshore. He also said that since the aircard has only about .6 watts of power, it is not really designed to be connected to a large cellular antenna on a tower with a wire run, even using the LMR 400 cable. What makes this all quite confusing is that the boat already has a booster and a large cell antenna and I would just be adapting that system to my aircard. I believe it had been used on a 3 watt cell phone before. Any thoughts on the advice I have received?

[GJH]

His information is out of date. The modern boosters modulate their "boost" according to the strength of signal present. There were problems 10 years ago with unmodulated boosters. The better signal you have the better your data performance will be, especially at the fringe.

However, I should note that I have carried a Digital Antenna amp for many years, as we cruised, at first on bare boat charters, the PNW and northern California waters, Texas gulf coast, then the eastern US from Tampa to New England on the Hatteras for the past 5+ years, which I also equipped with an 8 foot cell antenna. The carriers have all vastly improved their signals since then. I haven't hooked up the antenna or amplifier but once I think in the last two or three years. I'd guess there are still many spots in the Bahamas where it would be handy. There are also still a couple of virtual dead zones in North Carolina but even they have improved. Carriers still tend not to put towers where there are no customers.

[JLR]

So ... with that said, is there anyone who could recommend with first hand experience, what might work best with an ATT Sierra Wireless Lightning 3G card, and a cell antenna already on my tower? I presume my option is a booster of recent vintage with the existing setup or using the lmr400 cable to attach without a booster?

[GJH]

LMR 400 is very bulky stuff to hook up directly to the air card, you could try it, get the cable with a mini UHF on one end and then the right adapter to the antenna input on the card, or a short piece of Rg58 in between such as you would use between an amp and the card.

[JLR]

Thanks. I actually just hung up with Sierra Wireless, the maker of my aircard. They said as long as I have a good signal (which I do at 4 bars), increasing the signal strength will not increase the speed over the limitations of whatever ATT permits to flow over a 3G aircard. So, unless and until I can get a 4G ATT aircard that would permit me to assign it a static IP address, I am stuck with the limitations of 3G. DDNS will not work properly for this application.