RF Linx Corporation Wireless Networking

Wireless Solutions for Wireless ISPs, Hot Spots, Military, Commercial

Home Phone: (513) 777-2774

Calculations & Conversions

A Wireless System (more or less!)

System
Performance

System Performance

This calculator will give you one of three answers:

  1. If you leave distance blank it will apply the defined SAD factor (or default to 30%) to the Operating Margin and supply the max. distance (in Km and Miles) at which the Margin operates.
  2. If you enter the distance it will calculate the Operating Margin and the SAD factor.
  3. If you enter distance but leave RX or TX antenna gain (or both) blank it will apply the chosen SAD factor (or default it to 30% if none supplied) and generate the required antenna power. If both are left blank it will calculate a symmetrical antenna gain.

To RESET any parameter just set it to BLANK before clicking 'Calculate'

Notes: RX Sensitivity is ALWAYS expressed as a negative dBm (- dBm) and is the lowest power of signal your radio can handle. Its buried somewhere in your radio spec and will be typically in the range of -70 to -110 dBm. Don't guess or 'fudge' this number.

Note: If you solve for TX antenna (you leave it blank) and define a specific SAD factor it is applied to the TX budget and any TX antenna value will include this factor. If you then click Calculate again without changing anything, the SAD factor will be calculated to include the supplied TX antenna value and thus may show a lower value than the original one.

Calculations and equations used.

Frequency Distance   Result
 MHz  Km
OR

 Miles
(FS Loss)  dB
TX Power TX Cable TX Antenna  
 dBm
OR
 mW
 dBm  dB  dB
RX Sensitivity RX Cable RX Antenna  
 dBm  dB  dB  dB
Margin RX Power SAD Factor Theoretical Margin
 dBm  %  dB

System Performance Calculations

  1. Calculator normalises all distances to miles and feet during calculations.
  2. Free space loss = 36.56 + 20Log10(Frequency) + 20Log10(Dist in miles)
  3. mW to dBm = 10Log10(milliWatts) + 30
  4. dBm to mW = 10(dBm/10)
  5. RX Power = Margin - RX sensitivity
  6. Theoretical margin = TX power budget + RX power budget - free space loss
  7. SAD factor = Theoretical margin/TX power budget * 100 and shows the percentage of spare power on transmission.

* NOTE: Calculations provided by Zytrax. Calculators are provided for the use of our customer’s at their own risk and RF Linx, Inc. does not ensure their accuracy or applicability.

Power Budget

Use this calculator to walk through all the factors that make up your Power Budget. The 'Power Budget' is the the total power being output from the wireless system and is the sum of:

  • PLUS Radio Transmit Power (A above)
  • MINUS cables and connectors losses (B above)
  • PLUS antenna gain (C above).

Enter one parameter in each column (or leave blank) depending on what you know and the calculator will supply the appropriate conversions automatically. Up to 2 decimal places may be entered as 0.xx or .xx.

Note: Connector loss is generally small UNLESS you've got lots of 'em in which case you are probably in trouble anyway, or your cable is VERY short. Just leave the line blank if you are feeling lazy.

Calculations and equations used.

Radio and Antenna
Transmit Power Antenna Gain Power
 mW
OR

 dBm
 dB(i)  dB
Cable Loss
Cable Properties
(per 100 ft or m)
Cable Length  
 dB (100 ft)
OR
 dB (100 m)
 feet
OR

 meters
 dB
Connector Loss
Frequency in MHz No. of Connectors  
 MHz.  No.  dB
Budget
   dB

Power Budget Calculations

  1. mW to dBm = 10Log10(Watts) + 30
  2. feet to meters = .3048
  3. meters to feet = 3.28
  4. Calculator normalises all distances to kilometers and meters
  5. Connectors loss = 0.10 * square root (frequency in GHz)

* NOTE: Calculations provided by Zytrax. Calculators are provided for the use of our customer’s at their own risk and RF Linx, Inc. does not ensure their accuracy or applicability.

Antenna
Height

Fresnel Zones

Defines how much clearance you need (yes you need more than simple Line-of-Sight) and for longer links > 3 Km (2 miles) whether you may have a ground clearance problem from our friendly planet. M. Fresnel and his theories.

Enter the Total link distance (in Miles or Kilometers), if you do not enter an Obstacle distance (in Miles or Kilometers) the calculator will use the mid-point for all calculations (Note: assumes antennas at same height). Finally enter the system Frequency in MHz and then click the 'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.

The calculator will generate the radius of the 1st Fresnel zone only (at the obstable point or the mid-point), the 60% (no obstacle) radius and the height of the effective earth curvature at the mid-point of the Total link distance using the effective earth radius.

Calculations and equations used.

Total Link Obstacle Distance 1st Fresnel Zone Radius
 Km
OR

 Miles
 Km
OR
 Miles
 m
at
 Km
 ft
at
 Miles
Frequency   60% No Obstacle Radius
 MHz    m  ft
  Earth Height (mid-point)
     m  ft

Fresnel Zone Calculations

  1. Calculator normalises all distances to kilometers and meters
  2. Miles to Kilometers = 1.609
  3. Kilometers to miles = 0.621
  4. feet to meters = .3048
  5. meters to feet = 3.28
  6. 1st Fresnel Zone radius (Km) = 17.3 x Sqr root ((Obstacle Distance x (Total Link - Obstacle Distance)) / (Frequency in GHz x Total Link))
  7. 1st Fresnel Zone radius (miles) = 72.6 x Sqr root ((Obstacle Distance x (Total Link - Obstacle Distance)) / (Frequency in GHz x Total Link))
  8. Obstacle free radius = 0.6 x 1st Fresnel Zone radius
  9. Radius of nth Fresnel zone (meter) = sqr root ( (n x wave length x Obstacle distance x (Total Link - Obstacle Distance)) / Total Link )
  10. wave length (meters) = speed of light (299,792,458 m/s) / frequency in Hz
  11. Earth curvature calculation = (Total Link) 2 /(8 * effective earth radius)
  12. effective earth radius = 4/3 * Earth radius
  13. Earth radius = 3963 miles, 6378 Km

* NOTE: Calculations provided by Zytrax. Calculators are provided for the use of our customer’s at their own risk and RF Linx, Inc. does not ensure their accuracy or applicability.

dB to Watt
Conversions

dB to Watts Conversions

Power in milliWatts to dBm (and vice versa) . Enter the 'Transmit Power' (A or G above) in milliWatts OR the 'Power Ratio' in dBm and click the appropriate 'Calculate' button. 1 Watt = 1000 milliWatts.

Calculations and equations used.

Transmit Power   Result
mW  dBm
Power Ratio   Result
 dBm  mW

dBm to Watts Calculations

  1. mW to dBm = 10Log10(Watts) + 30
  2. dBm to mW = 10(dBm/10)

* NOTE: Calculations provided by Zytrax. Calculators are provided for the use of our customer’s at their own risk and RF Linx, Inc. does not ensure their accuracy or applicability.

Channel
Information

Channel Information & Overlap Guide

2.4GHz WiFi DSS Channels & Overlap Guide
Channel Overlap
Provided courtesy of Demarc Technologies Group
Channel Number North America Europe
1 2.412 GHz 2.412 GHz
2 2.417 GHz 2.417 GHz
3 2.422 GHz 2.422 GHz
4 2.427 GHz 2.427 GHz
5 2.432 GHz 2.432 GHz
6 2.437 GHz 2.437 GHz
7 2.442 GHz 2.442 GHz
8 2.447 GHz 2.447 GHz
9 2.452 GHz 2.452 GHz
10 2.457 GHz 2.457 GHz
11 2.462 GHz 2.462 GHz
12 N/A 2.467 GHz
13 N/A 2.472 GHz
14 N/A 2.484 GHz

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2.4GHz WiFi FHSS Channels
Region Lower Limit Upper Limit Regulatory Range
North America 2.402 GHz 2.480 GHz 2.400 - 2.4835 GHz
Europe 2.402 GHz 2.480 GHz 2.400 - 2.4835 GHz
2.4 GHz FHSS - Number of Operating Channels
Region Hopping Set Minimum
North America 79 75
Europe 79 20
2.4 GHz FHSS Channel Values
Channel Value Channel Value Channel Value
2 2.402 28 2.428 54 2.454
3 2.403 29 2.429 55 2.455
4 2.404 30 2.430 56 2.456
5 2.405 31 2.431 57 2.457
6 2.406 32 2.432 58 2.458
7 2.407 33 2.433 59 2.459
8 2.408 34 2.434 60 2.460
9 2.409 35 2.435 61 2.461
10 2.410 36 2.436 62 2.462
11 2.411 37 2.437 63 2.463
12 2.412 38 2.438 64 2.464
13 2.413 39 2.439 65 2.465
14 2.414 40 2.440 66 2.466
15 2.415 41 2.441 67 2.467
16 2.416 42 2.442 68 2.468
17 2.417 43 2.443 69 2.469
18 2.418 44 2.444 70 2.470
19 2.419 45 2.445 71 2.471
20 2.420 46 2.446 72 2.472
21 2.421 47 2.447 73 2.473
22 2.422 48 2.448 74 2.474
23 2.423 49 2.449 75 2.475
24 2.424 50 2.450 76 2.476
25 2.425 51 2.451 77 2.477
26 2.426 52 2.452 78 2.478
27 2.427 53 2.453 79 2.479
  80 2.480

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5GHz U-NII & CEPT Channels (802.11a & 802.11h)
Regulatory Domain Band (GHz) RF Linx Amplifier Base Model # Operating Channel # Channel Center (MHz)
United States U-NII Lower Band
(5.15 - 5.25)
5200xxx 36
40
44
48
5180
5200
5220
5240
United States U-NII Middle Band
(5.25 - 5.35)
5300xxx 52
56
60
64
5260
5280
5300
5320
CEPT
(European)
(5.47 - 5.725) 5600xxx 100
104
108
112
116
120
124
128
132
136
140
5500
5520
5540
5560
5580
5600
5620
5640
5660
5680
5700
United States U-NII Upper Band
(5.725 - 5.825)
5800xxx 149
153
157
161
5745
5765
5785
5805
United States Emergency Services
(4940 - 4990)
4900xxx    

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United States Frequency Allocation Chart

http://www.ntia.doc.gov/osmhome/allochrt.html

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FCC
Information

Basic EIRP Worksheets for Amplified Systems

  • Indoor & Outdoor AGC Amplified System (Word.doc)
  • Indoor & Outdoor Fixed Gain Amplified System (Word.doc)

Note:
All loss calculations are average references that are accurate to the best of our knowledge. These references cannot replace exact measurements of your individual system or application. See FCC Part 15. Use this information at your own risk.

Point to Point Link - 2.4 GHz (2.4-2.4835 GHz)
120° Degree Directional Antenna Pattern or Less
Power Input - dBm Antenna Gain - dBi Total EIRP - dBm Power in Watts
34 2 36 4.0
33 3 36 4.0
32 4 36 4.0
31 5 36 4.0
30 6 36 4.0
29 9 38 6.3
28 12 40 10.0
27 15 42 15.8
26 18 44 25.1
25 21 46 39.8
24 24 48 63.1
23 27 50 100.0
22 30 52 158.5

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Point to Point Link - 5.8 GHz (5.725-5.825 GHz U-NII Upper)
120° Degree Directional Antenna Pattern or Less
Power Input - dBm Antenna Gain - dBi Total EIRP - dBm Power in Watts
34 2 36 4.0
33 3 36 4.0
32 4 36 4.0
31 5 36 4.0
30 6 36 4.0
30 9 39 7.9
30 12 42 15.8
30 15 45 31.6
30 18 48 63.1
30 21 51 125.9
30 24 54 251.2
30 27 57 501.2
30 30 60 1000.0

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Point to Multi-Point Link - 2.4 GHz (2.4-2.4835 GHz) or 5.8 GHz (5.725-5.825 GHz U-NII Upper)
121° Degree Directional Antenna Pattern or More
Power Input - dBm Antenna Gain - dBi Total EIRP - dBm Power in Watts
36 0 36 4.0
35 1 36 4.0
34 2 36 4.0
33 3 36 4.0
32 4 36 4.0
31 5 36 4.0
30 6 36 4.0
29 7 36 4.0
28 8 36 4.0
27 9 36 4.0
26 10 36 4.0
25 11 36 4.0
24 12 36 4.0
23 13 36 4.0
22 14 36 4.0
21 15 36 4.0
20 16 36 4.0
19 17 36 4.0
18 18 36 4.0
17 19 36 4.0
16 20 36 4.0
15 21 36 4.0

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Point to Multi-Point Link - 5.3 GHz (5.25-5.35 GHz U-NII Middle)
121° Degree Directional Antenna Pattern or More
Power Input - dBm Antenna Gain - dBi Total EIRP - dBm Power in Watts
36 -6 30 1.0
35 -5 30 1.0
34 -4 30 1.0
33 -3 30 1.0
32 -2 30 1.0
31 -1 30 1.0
30 0 30 1.0
29 1 30 1.0
28 2 30 1.0
27 3 30 1.0
26 4 30 1.0
25 5 30 1.0
24 6 30 1.0
23 7 30 1.0
22 8 30 1.0
21 9 30 1.0
20 10 30 1.0
19 11 30 1.0
18 12 30 1.0
17 13 30 1.0
16 14 30 1.0
15 15 30 1.0
Free Space
Loss

Free Space Loss

Loss of power over distance (assuming no FRESNEL Effect and nothing in the way). This a very idealised calculation and in practice everything interferes with the signal but it will give you a reasonable approximation of the actual loss over distance.

Enter the system Frequency in MHz and the distance in either Kilometers (Km) or Miles below and then click the 'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.

Calculations and equations used.

Frequency Distance   Result
 MHz  Km
OR
 Miles
 dB

Free Space Calculations

  1. Free space loss = 36.56 + 20Log10(Frequency) + 20Log10(Distance in miles)
  2. Calculator normalises all distances to miles
  3. Miles to Kilometers = 1.609
  4. Kilometers to miles = 0.621

* NOTE: Calculations provided by Zytrax. Calculators are provided for the use of our customer’s at their own risk and RF Linx, Inc. does not ensure their accuracy or applicability.

Average
Loss Charts

Average Loss Charts

Average RF Splitter Losses
We suggest using not more than a 2 way splitter. 3dB = 25% of your range & performance
Split Loss (dB) @ 2.4GHz
2 Way 3.0
3 Way 4.8
4 Way 6.0
5 Way 7.0
6 Way 7.8
8 Way 9.0

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Average RF Cable Losses
Cable Type & Length Average Loss (dB)
Frequency 900MHz 2.4GHz 5.8GHz
LMR-100 A (10') 2.28 3.89 6.41
LMR-195 (10') 1.07 1.78 2.83
LMR-200 (10') 0.99 1.65 2.64
LMR-400 (100') 3.9 6.61 10.82
LMR-400 UF(100') 4.69 7.9 12.82
LMR-500 (100') 3.13 5.36 8.86
LMR-600 (100') 2.5 4.33 7.26
LMR-900 DB (100') 1.7 2.92 4.87
LMR-1200 DB (100') 1.27 2.21 3.77
Average RF Connector Losses
Per Connection Point 0.2dB

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Average Lightning Arrestor Losses
Lightning Arrestor Type Loss (dB) @ 2.4Ghz
RF Linx 2400 LAR 0.4 max / 0.2 typical
RFL-SP3 0.4 max / 0.2 typical

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Connector
Reference

Connector References

Links to other Web Resources

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News