Cables for WiFi
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.
| Cable | Thickness (Inches) | Loss for 100′ |
| LMR-1200 | 2.3 db/100′ | |
| LMR-900 | 0.870 | 2.9 db/100′ |
| LMR-600 | 0.590 | 4.4 db/100′ |
| LMR-400 | 0.405 | 6.7 db/100′ |
| Belden 9913 | 0.405 | 7.5 db/100′ |
| Belden 9914 | 0.405 | 8.7 db/100′ |
| RG-213 | 0.405 | 13.7 db/100′ |
| LMR-200 | 0.195 | 16.5 db/100′ |
| RG-8 | 0.242 | 21.6 db/100′ |
| RG-58 | 0.195 | 35 db/100′ |
| LMR-100A | 0.105 | 38.9 db/100′ |
| RG-174 | 0.110 | 75 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-213 | 15.2 * 70/100 = 10.64 |
| Belden 9913 | 8.15 * 70/100 = 5.71 |
| LRM-400 | 6.76 * 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
| Type | VSWR | Frequency | Loss (dB) | Loss at 2.4 GHz (dB) |
| BNC | < 1.12 + 0.007F | dc to 2 GHz | <0.1F | <0.24 |
| N | < 1.06 + 0.007F | dc to 10 GHz | <0.05F | <0.12 |
| TNC | < 1.07 + 0.007F | dc to 15 GHz | <0.05F | <0.12 |
| SMA | < 1.02 + 0.005F | dc to 18 GHz | <0.03F | <0.07 |
| SMB | < 1.08 + 0.017F | dc to 4 GHz | <0.12F | <0.29 |
| SMC | < 1.08 + 0.017F | dc 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)<p>
COAXIAL CABLE CHARACTERISTICS
—————————–
Attenuation @ 2.425 GHz
Cable Length: 100 feet (30.48 meters)
<B>The only problem is that the RG seems to be for 1 GHz. USE THIS LIST WITH CAUTION</b>
<p>
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