DG7YBN - Low Noise Yagis
 

  DG7YBN
  Low Noise Yagis
 

  DG7YBN
  Low Noise Yagis
 

Online Calculators  
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RF Calculators

  Last Update Apr. 16th 2015

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General Issues

li Equivalent isotropically radiated power EIRP
li Watts to dBm & dBm to watts
li dB to numeric & numeric to dB
li Watts in > Gain or Loss > Watts out

Receiver Sensitivity

li Temperature to dB (NF)
li dB (NF) to Temperature
li μV to dBm
li dBm to NF
li G/T Ratio

Impedance

li VSWR & Mismatch Loss

Links to other Online Calculators on dg7ybn.de

li DL6WU/G3SEK Boom Correction
li Yagi Stacking Distances acc. DL6WU
li Antenna Average Gain Correction acc. KF2YN
li Impedance of round and square Coaxial Lines
li Power Splitter Coaxial Lines, Z and lengths
li EIRP
li Watts to dBm & dBm to watts
li dB to numeric & numeric to dB
li Watts in > Gain:Loss > Watts out

Receiver Sensitivity

li Temperature to dB (NF)
li dB (NF) to Temperature
li μV to dBm
li dBm to NF
li G/T Ratio

Impedance

li VSWR & Mismatch Loss

Links to other Online Calculators on dg7ybn.de

li DL6WU/G3SEK Boom Correction
li Yagi Stacking Dist. acc. DL6WU
li Ant. Average Gain Corr. (KF2YN)
li Impedance of Coaxial Lines
li Power Splitter Z and lengths
li EIRP
li Watts to dBm & dBm to watts
li dB to numeric & numeric to dB
li Watts > Gain:Loss > Watts out

Receiver Sensitivity

li Temperature to dB (NF)
li dB (NF) to Temperature
li μV to dBm
li dBm to NF
li G/T Ratio

Impedance

li VSWR & Mismatch Loss

Links to other Calculators

li DL6WU/G3SEK BC
li Yagi Stacking acc. DL6WU
li Ant. AG Correction (KF2YN)
li Impedance of Coaxial Lines
li Power Splitter Z & lengths






EIRP : Equivalent isotropically radiated power


EIRP Calc.

Watts at Ant.     
Ant. Gain [dBi]




EIRP in W         


and kW




What is EIRP about?

EIRP is a term often used with the topic of RFI (Radio-Frequency Interference) and Radiation Power of Electromagnetic Fields. Simply put EIRP stands for the equivalent of fed power to an isotropic radiator (gain = 0 dBi per definition) vs. a directional antenna with certain gain over the iso.-radiator and other fed power. By referring to the iso.-radiator directional power levels in beam direction can easily be compared. In Amateur Radio use that could be comparing powers of two stations. Lets assume a DX setup for 432 MHz: one station is feeding 700 W into a 17.1 dBi antenna, the other 400 W into a 19.8 dBi antenna. Which one 'pumps' more radiation power into beam direction?

What maths are driving this calculator?

1. Conversion of Isotropic Gain of Antenna to numeric number

formula

2. EIRP is derived by multiplication of Power in watts with numeric Gain of antenna against an Isotropic Radiator

formula

'Gain,iso' = dBi = dBd + 2.15 dB. Example: 12.10 dBd is 14.25 dBi


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Watts to dBm & dBm to watts Conversion Calculator


W > dBm
W
  >    
dBm                    





dBm > W
dBm
  >    

W




dBm is Decibel-milliwatt, it references power to one mW - with 0 dBm = 1 mW

•    0 dBm = 0.001 W
•  10 dBm =   0.01 W
•  50 dBm =   100 W

What maths are driving this calculator?

formula

formula


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dB Conversion Calculator


Gain, numeric > dB
Gain [numeric]
  >    
Gain [dB]





Gain, dB > numeric
Gain [dB]
  >    

Gain [numeric]




This conversion works with GAIN and LOSSES:
• Gain  3.0 dB = 2.00 numeric
• Gain     0 dB = 1.00 numeric
• Gain -3.0 dB = 0.50 numeric

What maths are driving this calculator?

formulaformula

Getting a sense for numeric gain numbers as Power in Watts is multiplied with numeric Gain, see EIRP Calculator:
• 2.00 numeric = we know that 3 dB gain gives double output
• 1.00 numeric = adding 0 dB does not change anything
• 0.50 numeric = is half power out


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Amplification Gain or Attenuation to Watts in/out Calculator

formulaformula



Watts in, Gain or Loss to Watts out

Watts input
  >    
Gain/(-)Loss [dB]
       





Watts out [W]


What maths are driving this calculator?

Power Levels in dB can be summed (gain) or subtracted (loss).
So we convert Power Input in watts to Power Level (dB) refering to 1 watt (dBw)

formula

Next we add the Power Levels of fed power and gain or attenuation block

formula

or generalised for any chain of gain and attenuation blocks the formula looks like this:
Note the rather explicite notation 'Loss_x'. This commonly would be another G_x with gain < 1.00

formulaformulaformula

Finally we convert the resulting Power Level (dB) into watts again

formula



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Temperature to dB Calculator


Kelvin to dB Calculator

Kelvin [K]        





Computed dB or NF



What maths are driving this calculator?

formula

with To = 290 K = 17° Celsius mean ambient temp. (273 K = 0° C)


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And in reverse ... dB to Kelvin Calculator


dB to Kelvin Calculator


dB or NF        





Computed Temp. [K]



What maths are driving this calculator?

formula

with To = 290 K = 17° Celsius mean ambient temp. (273 K = 0° C)


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μV to dBm Calculator


μV to dBm Calculator


μV        

ohms        





Computed dBm



What maths are driving this calculator?

formulaformula

dBm is Power Level referring to 1 mW


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dBm to NF Calculator      Receiver Sensitivity to Noise Figure


dBm to NF Calculator


dBm
       

BW (kHz)
       

S/N (dB)
       





Computed dB or NF



• BW = Bandwidth
• dBm = Power Level referring to 1 mW
• To = 290 K or 17° C ambient

Using this calculator with Receiver Specs from a Data Sheets

As different S/N levels are used as well as bandwidth depends, look up those specifications
with the μV or dBm number given for sensitivity and enter to calculator form to yield a correct result

Typical numbers

• nominal BW's: CW or as SSB = from 2.4 ...3 kHz, AM = 6 kHz, FM = 12.5 ... 25 kHz
• CW Filter? => acc. filters bandwidth settings
• nominal S/N = 6, 10 or 12 dB


What maths are driving this calculator?

formulaformula

formulaformula


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G/T Calculator


G/T - Ratio


Gain (dBi)        

Temp. (K)        





Computed G/T (dB)



What maths are driving this calculator?

formula



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VSWR & Mismatch Loss

Z1 would be Zo or 'at Transmitter or Receiver' while Z2 could be antenna feedpoint impedance

Mismatch Loss (ML) expresses what Losses derive from connecting non similar impedances


VSWR & Mismatch Loss


Z1(Ω)
       

Z2(Ω) =
R + j        





Z2 absolute       
(Ω)
VSWR          
( / )
Refl. Coefficient Γ  
( / )
Return Loss   
(dB)
Mismatch Loss (dB)




Mismatch Loss application example:

Given a 50 ohms feedline coax of 10 m length with a loss of 1.2 dB shall be connected to a 75 ohms antenna. What is the total loss here?

The calculator puts out -0.177 dB for Mismatch Loss, the coax adds 1.2 dB, total loss is 1.377 dB.


What maths are driving this calculator?

Z2 in absolute numbers is

formula

with this we do the rest as follows

formula



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Who has been calculating since Apr. 2015?

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Who has been calculating?

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73, Hartmut, DG7YBN


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