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It takes about 6db to double your distance - since the power density at the receive site for double the distance is 1/2 * 1/2 = 1/4 of the power at the original distance. Thus you need 4 times the power if you double your distance, or 6 dB.

CableThickness (Inches)Loss for 100'
LMR-12002.3 db/100'
LMR-9000.8702.9 db/100'
LMR-6000.5904.4 db/100'
LMR-4000.4056.7 db/100'
Belden 99130.4057.5 db/100'
Belden 99140.4058.7 db/100'
RG-2130.40513.7 db/100'
LMR-2000.19516.5 db/100'
RG-80.24221.6 db/100'
RG-580.19535 db/100'
LMR-100A0.10538.9 db/100'
RG-1740.11075 db/100'

Depending on what you are using for your 21m (70') you may be able to gain a lot of range. The loss of cables at 70' are
RG-21315.2 * 70/100 = 10.64
Belden 99138.15 * 70/100 = 5.71
LRM-4006.76 * 70/100 = 4.73
In order to double the range you need 6 dB. You could do this by going from RG-213 to LMR-400. Or you could do it by using RG-213 and using 30' instead of 70', giving a loss of about 5 dB.

Access points such as the LinkSYS WAP-11 have about six inches of RG-174 from the radio to the antenna connector. This adds about 0.325 dB loss to the unit.

Connector Losses for 802.11

TypeVSWRFrequencyLoss (dB)Loss at 2.4 GHz (dB)
BNC< 1.12 + 0.007Fdc to 2 GHz<0.1F<0.24
N< 1.06 + 0.007Fdc to 10 GHz<0.05F<0.12
TNC< 1.07 + 0.007Fdc to 15 GHz<0.05F<0.12
SMA< 1.02 + 0.005Fdc to 18 GHz<0.03F<0.07
SMB< 1.08 + 0.017Fdc to 4 GHz<0.12F<0.29
SMC< 1.08 + 0.017Fdc to 10 GHz<0.06F<0.14

Personally I have a couple of interesting suggestions - D-LINK and others have a USB access point available - and there is an Open Source driver on SourceForge. USB can be up to 25M from the computer with extension cables. Have a USB access point at the antenna (NOTE: This is not good in if you g et lots of static buildup or thunder storms).

Alternately the cost of an Etherenet Access Point might be cheaper (or easier) than the cost of antenna cables. Also remember that coax does not live forevere. Here in OZ we have birds that eat coax, and also hot weather does not help. CoAx outside might last 5 years before needing replacing on a rood in some areas. Once a coax is no longer waterproof, water gets in and the loss goes really high.

If anyone has any questions please ask...
Channel Frequency (GHz)
1 2.412
2 2.417
3 2.422
4 2.427
5 2.432
6 2.437
7 2.442
8 2.447
9 2.452
10 2.457
11 2.462

from http://www.qsl.net/kb9mwr/projects/wireless/2400coax.txt(Dead Link)

COAXIAL CABLE CHARACTERISTICS ----------------------------- Attenuation @ 2.425 GHz Cable Length: 100 feet (30.48 meters) The only problem is that the RG seems to be for 1 GHz. USE THIS LIST WITH CAUTION

Cable Type Z dB Loss ~~~~~~~~~~ ~~~~ ~~~~~~~ RG-8....... 52.0 10.81 RG-8 Foam.. 50.0 10.8 RG-8A...... 52.0 10.81 RG-9....... 51.0 10.83 RG-9A...... 51.0 10.83 RG-9B...... 50.0 10.77 RG-11...... 75.0 10.78 RG-11A..... 75.0 10.78 RG-12...... 75.0 10.85 RG-12A..... 75.0 10.85 RG-17...... 52.0 3.76 RG-17A..... 52.0 3.76 RG-58...... 53.5 18.79 RG-58 Foam. 53.5 18.66 RG-58A..... 53.5 21.86 RG-58B..... 53.5 18.78 RG-58C..... 50.0 22.00 RG-59...... 73.0 18.81 RG-59 Foam. 75.0 13.94 RG-59A..... 73.0 18.81 RG-62...... 93.0 14.03 RG-62A..... 93.0 14.03 RG-62B..... 93.0 14.03 RG-141..... 50.0 18.72 RG-141A.... 50.0 18.72 RG-142..... 50.0 18.69 RG-142A.... 50.0 18.69 RG-142B.... 50.0 18.61 RG-174..... 50.0 61.22 RG-213..... 50.0 10.78 RG-214..... 50.0 10.73 RG-215..... 50.0 10.84 RG-216..... 75.0 10.85 9913 Belden 50.0 7.7 LMR-400.... 50.0 6.60 LMR-500.... 50.0 5.40 LMR-600.... 50.0 4.30 LMR-900.... 50.0 2.90 LMR-1700... 50.0 1.70 Alum. 1/2". 50.0 3.40 Alum. 3/4". 50.0 2.64 Alum. 7/8". 50.0 2.01 Alum. 1/2". 75.0 3.77 Alum. 3/4". 75.0 2.79 Alum. 7/8". 75.0 2.48 Heliax 1/2" 50.0 3.9 Heliax 7/8" 50.0 2.3

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Radioactive Networks is a consulting company with extensive experience in mobile tracking technologies. We have used these technologies successully in events as diverse as the Olympics, the IronMan World Championships in Hawaii to a technology demonstration in Hollywood, Ca. Our unique catalog of Hardware and Software allow us to provide an economical solution to almost any business need.

Based in Sydney, Australia, Radioactive Networks have the experience needed to complete even the most demanding mobile tracking projects.

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This page was last updated 2005-08-31 14:59:40
This page was last compiled 2005-11-15 19:02:54
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