Animated Flag

    SEARCH
About Hamuniverse
Antenna Design
Ask Elmer
About Batteries
Code Practice
Computer Help
Electronics
FCC Information
Ham Hints -
Humor
Ham Radio News!
HF & Shortwave

License Study
Links
Midi Music
Reading Room
Repeater Basics
Repeater Builder Info
RFI Tips and Tricks
Ham Satellites
Shortwave Listening
SSTV
Support The Site
STORE

Vhf and Up
Contact
Site Map

Privacy Policy

Legal Stuff

Coaxial Cable Characteristics and Data
Used in Amateur Radio Stations


It is of importance when making decisions about getting the right coax for your Ham Station to understand that there are trade-offs that have to be considered between transmitter power, antenna gain, coax loss, erp, and your total Ham Station system performance.
Your bank account may also enter into the equation like most Hams.

The db differences in gains or losses on transmit and receive between the choices available to you are the important issue.

A difference of 3 db either way will not be apparent to the stations that you are communicating with on the other end; around the block or around the world. They won't hear or see (on the S meter) any difference if you run your transmitter at 50 watts instead of its maximum 100 watt output power as an example.
This is a difference of about 3db! The same ratio holds true comparing 500 watts with 1000 watts!
Now take this same analogy and apply it to coax.
Here is an example:
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 usually won't know the difference, and usually, 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

.26.831.92.74.15.96.59.823.032.0

8 MINI, 8X

 1.12.53.85.47.98.813.026.0 

LMR -240

.24.761.72.43.44.97.57.914.218.7

8, 8A, 10A, 213 (RG8/8A hard to find )

.15.551.31.92.74.17.58.016.027.0

9913, 9086, 9096

  0.91.41.82.64.24.5 13.0

4XL8IIA, FLEXI 4XL

  0.91.41.82.64.24.5 13.0

LMR-400

  .91.2 2.54.14.3  

LMR-500

  .71.0 2.03.23.4  

LMR-600

  .6.8 1.42.52.7  

8214

 .601.21.72.74.2 7.814.222.0

9095

  1.01.82.63.86.07.5  

9, 9A, 9B, 214

.21.661.52.33.35.07.88.818.027.0

11,11A,12,12A,13,13A, 216

.19.661.62.33.34.8 7.816.526.5

14, 14A, 217

.12.411.01.42.03.1 5.512.419.0

17,17A,18,18A, 218, 219

.06.24.62.951.52.4 4.49.515.3

55B, 223

.301.23.24.87.010.014.316.530.546.0

58

.331.23.14.66.910.514.517.537.560.0

58A, 58C

.441.43.34.97.412.020.024.054.083.0

59, 59B

.331.12.43.44.97.011.012.026.542.0

62, 62A, 71A, 71B

.25.851.92.73.85.38.38.718.530.0

62B

.31.902.02.94.26.2 11.024.038.0

141,141A, 400, 142, 142A

.30.902.13.34.76.9 13.026.040.0

174

2.33.96.68.912.017.528.230.064.099.0

178B,196A

2.65.610.514.019.028.0 46.085.0100

188A, 316

3.16.09.611.414.216.7 31.060.082.0

179B

3.05.38.510.012.516.0 24.044.064.0

393, 235

 .61.42.13.14.5 7.514.021.0

402

 1.22.73.95.58.0 13.026.026.0

405

       22.0  

LDF4-50A

.06.21.47.68.981.42.22.34.35.9

LDF5-50A

.03.11.25.36.53.781.21.42.53.5

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

1.010501002004009001000

55, 6A, 212

40001500800550360250 150

8 MINI, 8X

40001500800550360250 150

8, 8A,10A, 213

110003500

1500

975685450 230

9913, 9086, 9096

 35001500975685450 230

4XL8IIA, FLEXI 4XL

 35001500975685450 230

9095

1100035001500975685450 230

9, 9A, 9B, 214

900027001120780550360 200

11,11A,12,12A,
13,13A, 216

800025001000690490340 200

14,14A, 217

200006000240016001000680 380

17,17A,18,18A,
218, 219

50000140005400360023001400 780

55B, 223

56001700700480320215 120

58

35001000450300200135 80

58A, 58C

32001000425290190105 60

59, 59B

39001200540270270185 110

62, 62A, 71A, 71B

45001400630440320230 140

62B

38001350600410285195 110

141,141A, 400
142,142A

1900090003500240016001100 650

174

1000350160808060 35

178B,196A

1300640330240180120 75

188A, 316

1500770480400325275 150

179B

30001400750480420320 190

393, 235

 250009500630043002800 1700

402

 90003500240016001100 650

405

       130

LDF4-50A

190006100260018801310906563551

LDF5-50A

440007700774053803720255016201520
LMR-400 Power handling = 2100 watts <30Mhz

Understanding the effects of ERP vs antenna gain.
ERP CHART

Antenna Gain (dbd)

100 Watts Input
(Rounded)

1

126

2

158

3

199

4

251

5

316

6

398

7

501

8

631

9

794

10

1000

11

1259

12

1585

13

1995

14

2512

15

3162

16

3981

17

5112

18

6310

19

7943

20

10,000

Note that these numbers above assume no loss in feedline or antenna and used the CSG Calculator)
You will always have some bit of loss in your feedline but this calculator is considering only power and antenna gain.
Example: Coax loss
Using 100 watts output from transmitter and assuming your old coax had 3db loss, with no changes to antenna system except replacing your old coax and also assuming the new coax has 0db loss, the ERP of the antenna system would increase by 3db and would be 199 watts.
This is a 3db gain achieved by the new coax.
Example: Antenna Gain
You use an antenna that has 6dbd gain vs the old one that had 0dbd gain.
What effect does this have on your erp?
By using the chart above, you will see that with 100 watts at the antenna feedpoint, your effective radiated power would be 398 watts!


Remember, you have to achieve about 6db gain or loss to to make much difference on the air to the other station on receive.


Using this table, you should see that with every 3db increase or decrease, your effectively doubling the ERP or cutting it in half.
Your feedline will always have some loss so in calculating your total antenna system loss, always subtract the total loss of your feedline from your antenna gain.

Example:

Your antenna gain is 6dbd.

Your coax loss is 2 db per 100 feet as stated by the mfg. You use 50 feet.

Your total system gain or loss would be:

Antenna gain 6dbd - loss of 1db(50 feet) = total gain (or loss) = 6 - 1 = 5 db

Another example:

You add 100 feet of coax with 3 db loss at your operating frequency to an antenna with 0 dbd gain.

So 0db - 3db = -3db loss in signal strength...you just cut your signal in half.



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
95ladder line
82twin-lead
79coaxial cable / foam dielectric
75RG-6 and RG-8 coax (thick)
66RG-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

Our ged test online certkiller and examsheets security+ book exam provide you 100% pass guarantee. You can get access to braindumps ccdp and testking pmp exam prep with multiple prep resources of testinside sat prep courses.
           


Copyright 2000 - 2012 N4UJW Hamuniverse.com and or article author
Powered by Ham Radio!