North Johor Ham Community - Coaxial Cable Characteristics and Data

Your present coax is 100 feet long and has a loss of 3db per 100 feet.You change it to the same length, 100 feet, using a more expensive coax that has only about .1db loss per 100 feet.
(Very Expensive Stuff!)
This is about a 3db increase in signal strength to the antenna that you were loosing in the old coax.
The station on the other end still won't know the difference, neither will your receiver!
A difference of 3 db or less between two antennas, two types of coax, or two station configurations is usually not sufficient to justify the higher costs of the more expensive, lower loss, coaxial cable unless you are a perfectionist with lots of money.

However, a difference of 6 db may well justify the more expensive approach with the higher quality coax or antenna setup.
Remember, if you can't increase your transmit or receive signal by at least 5 or 6 db or more, if may not be worth the effort and expense.

The tables below should help you decide what if any coax changes you need to make.
Color Key:
Green shade 50 - 52 ohm

Coax dB Loss per 100 Feet using common coax types:

dB Loss / 100 feet
Frequency Mhz
Cable Type 1.0 10 50 100 200 400 900 1000 3000 5000 6A, 212 .26 .83 1.9 2.7 4.1 5.9 6.5 9.8 23.0 32.0 8 MINI, 8X 1.1 2.5 3.8 5.4 7.9 8.8 13.0 26.0 LMR -240 .24 .76 1.7 2.4 3.4 4.9 7.5 7.9 14.2 18.7 8, 8A, 10A, 213 .15 .55 1.3 1.9 2.7 4.1 7.5 8.0 16.0 27.0 9913, 9086, 9096 0.9 1.4 1.8 2.6 4.2 4.5 13.0 4XL8IIA, FLEXI 4XL 0.9 1.4 1.8 2.6 4.2 4.5 13.0 LMR-400 .9 1.2 2.5 4.1 4.3 LMR-500 .7 1.0 2.0 3.2 3.4 LMR-600 .6 .8 1.4 2.5 2.7 8214 .60 1.2 1.7 2.7 4.2 7.8 14.2 22.0 9095 1.0 1.8 2.6 3.8 6.0 7.5 9, 9A, 9B, 214 .21 .66 1.5 2.3 3.3 5.0 7.8 8.8 18.0 27.0 11,11A,12,12A,13,13A, 216 .19 .66 1.6 2.3 3.3 4.8 7.8 16.5 26.5 14, 14A, 217 .12 .41 1.0 1.4 2.0 3.1 5.5 12.4 19.0 17,17A,18,18A, 218, 219 .06 .24 .62 .95 1.5 2.4 4.4 9.5 15.3 55B, 223 .30 1.2 3.2 4.8 7.0 10.0 14.3 16.5 30.5 46.0 58 .33 1.2 3.1 4.6 6.9 10.5 14.5 17.5 37.5 60.0 58A, 58C .44 1.4 3.3 4.9 7.4 12.0 20.0 24.0 54.0 83.0 59, 59B .33 1.1 2.4 3.4 4.9 7.0 11.0 12.0 26.5 42.0 62, 62A, 71A, 71B .25 .85 1.9 2.7 3.8 5.3 8.3 8.7 18.5 30.0 62B .31 .90 2.0 2.9 4.2 6.2 11.0 24.0 38.0 141,141A, 400, 142, 142A .30 .90 2.1 3.3 4.7 6.9 13.0 26.0 40.0 174 2.3 3.9 6.6 8.9 12.0 17.5 28.2 30.0 64.0 99.0 178B,196A 2.6 5.6 10.5 14.0 19.0 28.0 46.0 85.0 100 188A, 316 3.1 6.0 9.6 11.4 14.2 16.7 31.0 60.0 82.0 179B 3.0 5.3 8.5 10.0 12.5 16.0 24.0 44.0 64.0 393, 235 .6 1.4 2.1 3.1 4.5 7.5 14.0 21.0 402 1.2 2.7 3.9 5.5 8.0 13.0 26.0 26.0 405 22.0 LDF4-50A .06 .21 .47 .68 .98 1.4 2.2 2.3 4.3 5.9 LDF5-50A .03 .11 .25 .36 .53 .78 1.2 1.4 2.5 3.5

Note: These tables are typical specifications for comparison only.
Values may not be exactly as quoted by a specific mfg. Power Handling Characteristics of Coax

Power Handling Vs Mhz
Coax type 1.0 10 50 100 200 400 900 1000 55, 6A, 212 4000 1500 800 550 360 250 150 8 MINI, 8X 4000 1500 800 550 360 250 150 8, 8A,10A, 213 11000 3500 1500 975 685 450 230 9913, 9086, 9096 3500 1500 975 685 450 230 4XL8IIA, FLEXI 4XL 3500 1500 975 685 450 230 9095 11000 3500 1500 975 685 450 230 9, 9A, 9B, 214 9000 2700 1120 780 550 360 200 11,11A,12,12A,
13,13A, 216 8000 2500 1000 690 490 340 200 14,14A, 217 20000 6000 2400 1600 1000 680 380 17,17A,18,18A,
218, 219 50000 14000 5400 3600 2300 1400 780 55B, 223 5600 1700 700 480 320 215 120 58 3500 1000 450 300 200 135 80 58A, 58C 3200 1000 425 290 190 105 60 59, 59B 3900 1200 540 270 270 185 110 62, 62A, 71A, 71B 4500 1400 630 440 320 230 140 62B 3800 1350 600 410 285 195 110 141,141A, 400
142,142A 19000 9000 3500 2400 1600 1100 650 174 1000 350 160 80 80 60 35 178B,196A 1300 640 330 240 180 120 75 188A, 316 1500 770 480 400 325 275 150 179B 3000 1400 750 480 420 320 190 393, 235 25000 9500 6300 4300 2800 1700 402 9000 3500 2400 1600 1100 650 405 130 LDF4-50A 19000 6100 2600 1880 1310 906 563 551 LDF5-50A 44000 7700 7740 5380 3720 2550 1620 1520

ERP CHART

Antenna or Coax Watts 100 Watts input
Gain in dB Multiplier ERP
1 1.2 120
2 1.6 160
3 2.1 210
4 2.5 250
5 3.2 320
6 4.0 400
7 5.1 510
8 6.3 630
9 8.0 800
10 10.2 1020
11 12.6 1260
12 15.9 1590
13 20.0 2000
14 25.1 2510
15 31.6 3160
16 39.9 3990
17 50.2 5020
18 63.3 6330
19 79.5 7950
20 100.0 10000

Example:
Using 100 watts output from transmitter with no changes to antenna system except replacing your old coax with 3db less loss coax, the ERP of the antenna system would increase to 210 watts.
This is a 3db gain achieved by the new coax.
Remember, you have to achieve about 6db gain or loss to to make much difference

Using this table, you should see that with every 3db increase, your effectively doubling the ERP.

Velocity Factor of Propagation Through Coaxial Cable

The velocity factor is the speed at which an RF signal travels through a material compared to the speed the same signal travels through a vacuum. The velocity of propagation is inversely proportional to the dielectric constant.
Lowering the constant increases the velocity.
Generally, the higher the velocity factor, the lower the loss through a coaxial cable.

"Typical" Velocity Factor of Coaxial Cable by type

VF% Transmission line type 95 ladder line 82 twin-lead 79 coaxial cable / foam dielectric 75 RG-6 and RG-8 coax (thick) 66 RG-58 and RG-59 coax (thin)

General Rules for Coaxial Cable
D = diameter of insulation under the shield
d = diameter of inner conductor.

Velocity Factor, Velocity of Propagation, Vp
The higher the velocity factor, the lower the loss through the cable.
Raising the D/d has no effect on Vp
Raising the dielectric constant lowers Vp

Capacitance
Raising the D/d ratio lowers capacitance
Raising the dielectric constant raises capacitance
Impedance Raising the D/d radio raises impedance
Raising the dielectric constant lowers impedance

Attenuation or Loss
Raising the D/d ratio lowers attenuation
Raising the dielectric constant raises attenuation