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Ham Radio - RF Units Conversion
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9 U$ A0 S6 L) O& C. f7 pDecibel Conversions
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dB = 10 log [P2/P1]
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Decibels relative to Power
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Decibel Conversions: Z3 M( Y, e9 w) W
/ w/ j! j) b0 \5 |" ydB = 20 log [V1/V2]7 y1 ~( R1 g) `
) R' s, s Q( A: O' ~- kDecibels relative to Voltage across same resistance
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Decibel Conversions
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* K( u6 Z7 U6 s, z7 Q( T- o1 PdB = 20 log [I1/I2]$ K, U! u! r+ x, S. \' V$ r
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Decibels relative to Current through same resistance
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0 Y( n" c& `- Y5 SDecibel Conversions
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) `* J6 t% O7 _- `$ cdBmV = 20 log [Signal (mV)/1mV]8 Q4 j. e' R! c2 P. e
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Decibels relative to one microvolt across same resistance
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Decibel Conversions' [5 T- s7 m+ k4 |# F
* L( L8 a) o+ r: n! u6 }dBm = 10 log [Signal (mW)/1mW]. Y1 J8 |6 Y) b' w \0 G# u4 e2 m+ j
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Decibels relative to one milliwatt( ?# k& |- n& {) A8 y( d3 L
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Decibel Conversions. U5 A# z Y8 O U
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dBmA = 20 log [Signal (mA)/1mA]
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! O3 `( B/ R4 s0 e6 J3 p% G% tDecibels relative to one microamp through same resistance
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! @/ Z. ?+ `8 H$ t& m& o: o1 J# sPower Conversions
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: b8 g$ l. }- y+ n7 O2 ddBm = dBw + 30' R5 U( J* R7 F, ^8 b" N
2 L+ |2 h; S6 u5 _Conversion from dBw to dBm.
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. j6 W8 L6 ]& T' SVoltage Conversions( R8 X4 _2 e! X: I7 b2 v+ g
9 e& O! _ Y' n6 IdBuv = dBv + 120
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2 m) p' N" V8 L/ UConversion from dBv to dBuv.9 ^$ I5 O! E, p4 b7 ^
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* A! L1 N% s7 V }! A. V z* WVoltage to Power3 A6 ?; ?1 t* f
9 Y1 S9 u2 |4 w0 ~dBm = dBmV - 107
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; V L* z& z0 I, {7 OWhere the constant 107 is as follows:
& b7 d7 b: z7 L4 Y! \* RF systems are matched to 50W
8 l- i$ ~0 {7 D& I. uP = V2 / R
7 Z) T+ b& h8 b10Log10[P] = 20Log10[V] - 10Log10[50W]
8 e8 Z3 d; [3 J- LV = (PR)0.5 = 0.223 V = 223000 mV% h$ @& _$ C: s
For a resistance of 50W and a power of 1 mW:
7 R9 z V. X6 _9 [" l. M8 J5 w20Log10[223000mV] = 107 dB & u( B5 h- j/ g3 ~! E, i
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2 g" p$ n( Y0 WPower Density7 z% F" ]+ Q( E2 i$ c3 e, U
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dBw/M2 = 10Log10[V/M - A/M]2 g6 b, t) c0 d0 t
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Decibel-Watts per square meter.
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, _$ I7 n( F' |. n E4 WPower Density
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; W( n8 a8 T( T; s$ G1 RdBm/M2 = dBw/M2 + 30
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Where the constant 30 is the decibel equivalent of the factor 1000 used to convert between W and mW:
0 n2 L4 g0 d7 w L8 H10Log10[1000] = 307 P: i% M4 y4 d# L& t3 f# x" f
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Conversion Units
" l: ?1 u% t# _; `2 p4 F6 h P0 XdB = decibels (Log10)
4 {+ l; y, x3 f$ X+ r) K" Iu = micro = 10E-6
$ J: n+ {& {+ I* nm = milli = 10E-3 @; m4 C4 h# e3 E
dBw = decibels relative to one watt
# O. f! }- @. P2 q8 tdBm = decibels relative to one milliwatt
3 m y& x" ` TdBV = decibels relative to one volt
* W: T; {, B1 B+ G9 d2 U' D& v+ C/ SdBuV = decibels relative to one microvolt" |8 @; J" g6 C4 L6 o. P2 W3 \, ^
dBuA = decibels relative to one microamp! X5 t! \! {/ Q# i8 z; O
V = Volts; C. ]' q4 F* M+ u- H+ @& Q
A = Amps# I4 n- ?6 E. k" J
I = Current) X4 H" z* ~: c% |, \4 O6 j! a
R = Ohms (50)
+ |5 d0 t& f' F, r: T6 B. fW = Watts
+ ^# m# r/ W* t6 O/ VP = Power
- I. A0 k: b5 h: GM = Meter |
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