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Choosing an antenna for my wireless internet

David Williams

David Williams

EF4
Joined
Oct 14, 2008
Messages
300
Location
Lake Tahoe, CA
Hey everybody. I need some help choosing an antenna for my wireless internet. Everyone says that I need an antenna in order to get my wireless connection out in the field. I will be getting verizon's 5GB plan next week and some aircard or usb modem or another... I suppose it doesn't really matter. However, I am trying to narrow down on the antenna. I have been pointed in the direction of the Shasta/CA-819 amp + MAK Mobile Accessory Kit. Apparently, it is a combo special right now for 199.95 from Maximum signal. Anybody think this is a good purchase or would you suggest something else? Cheers,
David
 
There is one element in these external cellular antenna systems that most people (except for us ubergeek hams) overlook.

Coaxial cable is naturally very lossy stuff when you're looking at the 500-2000MHz frequency range that cellphones function in. When you're talking about the light weight RG-59A/U or even worse RG-174 coax that is typically used with cellular antennas the power loss is staggering.

For instance, at 1800MHz, the typical lower frequency on 3G networks, you can expect a loss of approximately 5dB in a 10' length of RG-174 (the really thin stuff) This means that about 75% of your signal is being wasted heating your cable. The numbers are a little better if heavier cable such as RG-59 or RG-58 are used, but only slightly. 10' of cable will still result in a 50% reduction in output power and received signal strength.

I've found that by far the most effective setup is to actually run a 10' USB cable up to the roof of the vehicle, and enclose a USB modem in a piece of PVC pipe stuck to a mag mount. That typically bought me a 10-15dB SNR improvement over the USB modem in the cab of the truck, and by adding a quality external antenna on a *very* short coax lead (2' or less) something closer to 20dB is not unreasonable. I tried 5 different spots in my area that are completely dead with the modem inside the cab of the truck, and in all but one I had atleast 4 bars with the modem on the roof. The other spot had 2 bars instead of zero. If I were to add an external amp as well, also on the roof and connected with short coax runs, the improvement would be even more dramatic.

My Dad recently suggested I sell the enclosure I built for my USB modem. Perhaps there could actually be a market for it if I included the external antenna and perhaps even an amp.
 
davidduncanw said:
Hey everybody. I need some help choosing an antenna for my wireless internet. Everyone says that I need an antenna in order to get my wireless connection out in the field. I will be getting verizon's 5GB plan next week and some aircard or usb modem or another... I suppose it doesn't really matter. However, I am trying to narrow down on the antenna. I have been pointed in the direction of the Shasta/CA-819 amp + MAK Mobile Accessory Kit. Apparently, it is a combo special right now for 199.95 from Maximum signal. Anybody think this is a good purchase or would you suggest something else? Cheers,
David
Click to expand...

I've used the kit you mentioned for the last few years and it works really well. Something to think about when you purchase your data card from Verizon is to make sure it has the ability to hook up to an external antenna. The datacard would normally have an SMA connector where you can hook up an adapter cable to run to the amp. The antenna that comes in the kit works just fine. Last year I decided to purchase the rather inexpensive 3db indoor glass mount model found here: https://www.maximumsignal.net/store/product.php?productid=16216&cat=5&page=1 and I was pleasantly surprised at how well it worked. I thought it actually worked better than the 5db mag mount model that came in the kit, plus there are no cables to run to the roof of your ride. What it boils down to is what works best for you and a bit of trial and error. If money is concern, just get the kit and see what you think as everything you need is sold with the kit.

One other thing to do is pick up some extra 2 or 3 amp fuses (the old glass type from a few years ago) at your local auto store. There is a fuse in the cable housing where the cable plugs into your cigarette lighter and if the fuse blows your amp won't function. I had to get in touch with Gordon Spencer out the field and he advised me why the indicator light on my amp wasn't glowing. Some cheap insurance and very well worth the $1 you'll spend on a box of fuses. Just check the amperage on the fuse that comes inside of the housing with your cable and get the same.

Mark
 
hey Mark.... thanks for the advice on the fuses. After purchasing a booster kit myself, I could see how a fuse could easily blow and a simple $1 part could fix a rather frustrating problem!!
 
So, if I have mobile internet going (my computer plugged into the cigarette lighter) and an external antenna (which looks like it needs its own power source), how will I about getting power to both devices?
 
davidduncanw said:
So, if I have mobile internet going (my computer plugged into the cigarette lighter) and an external antenna (which looks like it needs its own power source), how will I about getting power to both devices?
Click to expand...

Additional power points? Inverter for the computer? Most new cars/trucks/suvs have 3 or more 12v power points. Radio Shack, Target, or Wal Mart will sell 12v plugs you can add if your handy with tools. Just don't do this yourself if you know nothing about wiring!

Jeff
 
Jeff Russell said:
Additional power points? Inverter for the computer? Most new cars/trucks/suvs have 3 or more 12v power points. Radio Shack, Target, or Wal Mart will sell 12v plugs you can add if your handy with tools. Just don't do this yourself if you know nothing about wiring!

Jeff
Click to expand...

Unfortunately, I know nothing about any of this stuff. I am trying to learn fast and get my car prepared for the season... which will be decending on us at any time. Jeff, do you know of any websites you can direct me to that simply explain all this stuff? Thanks, David
 
Cyfre amplifiers use software driven amplification . This software compensates for RF loss in cabling and connections . I have customers with 200 foot runs of cable with the same results as if they were only running 10 feet of cable. By the way Cyfre amplifiers are the only amplifiers that do this.

Dave Marshall said:
There is one element in these external cellular antenna systems that most people (except for us ubergeek hams) overlook.

Coaxial cable is naturally very lossy stuff when you're looking at the 500-2000MHz frequency range that cellphones function in. When you're talking about the light weight RG-59A/U or even worse RG-174 coax that is typically used with cellular antennas the power loss is staggering.

For instance, at 1800MHz, the typical lower frequency on 3G networks, you can expect a loss of approximately 5dB in a 10' length of RG-174 (the really thin stuff) This means that about 75% of your signal is being wasted heating your cable. The numbers are a little better if heavier cable such as RG-59 or RG-58 are used, but only slightly. 10' of cable will still result in a 50% reduction in output power and received signal strength.

I've found that by far the most effective setup is to actually run a 10' USB cable up to the roof of the vehicle, and enclose a USB modem in a piece of PVC pipe stuck to a mag mount. That typically bought me a 10-15dB SNR improvement over the USB modem in the cab of the truck, and by adding a quality external antenna on a *very* short coax lead (2' or less) something closer to 20dB is not unreasonable. I tried 5 different spots in my area that are completely dead with the modem inside the cab of the truck, and in all but one I had atleast 4 bars with the modem on the roof. The other spot had 2 bars instead of zero. If I were to add an external amp as well, also on the roof and connected with short coax runs, the improvement would be even more dramatic.

My Dad recently suggested I sell the enclosure I built for my USB modem. Perhaps there could actually be a market for it if I included the external antenna and perhaps even an amp.
Click to expand...
 
Gordon,
Are there differences between the amps and boosters? I hear a lot of people talking about boosters. Are they the same or different? Is a booster and amp nessecary?
 
They are the same thing just different terminology by different people . Technical term is a bi-directional cellular amplifier[QUOTE=davidduncanw;217271]Gordon,
Are there differences between the amps and boosters? I hear a lot of people talking about boosters. Are they the same or different? Is a booster and amp nessecary?[/QUOTE]
 
Chris Strahan said:
hey Mark.... thanks for the advice on the fuses. After purchasing a booster kit myself, I could see how a fuse could easily blow and a simple $1 part could fix a rather frustrating problem!!
Click to expand...

Hey Chris - you're welcome dude and it was nice to meet you at the convention! I remember that day so vividly. It was on May 2, 2008, when the tornadoes rolled through central Arkansas around mid-day (Lonoke county around Carlisle and Hazen). The day before we were in Fredonia KS (SW of Chanute) and there were tornadoes further south in Oklahoma around Pawhuska. We took off that morning and were about an hour behind it all day trying to play catch up. The blown fuse ended up being a non-issue because we were on I-40 all day and had great internet connectivity the whole way.

I kept staring at the LED indicator light thinking maybe the LED bulb had burned out. As it turned out it was the dumb fuse that had blown, so the amp wasn't working. I felt so dumb after Gordon told me what the problem was, but I learned something along the way so thought I would share it for others!

Mark
 
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