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Ham Radio - RF Units Conversion 2 k5 }) s+ ?5 g4 E# X- ]6 S# I
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Decibel Conversions
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, L+ m* O3 Z/ D, ]' R" GdB = 10 log [P2/P1]
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5 v8 ^& P5 G5 r( nDecibels relative to Power
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# ^; i7 D9 I3 l% D9 E. UDecibel Conversions
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dB = 20 log [V1/V2]
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Decibels relative to Voltage across same resistance
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Decibel Conversions- g4 }' N9 p. d3 o# H- F4 E
1 m1 C6 k8 B7 q( w/ g2 tdB = 20 log [I1/I2]" Z8 t( W4 {3 m& Y
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Decibels relative to Current through same resistance3 ^* G" z9 |2 l) r( F
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7 p/ K/ I; N% }9 ?0 m' q' SDecibel Conversions
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dBmV = 20 log [Signal (mV)/1mV]& X; }) D* V1 k
2 S1 E& S: x, s# VDecibels relative to one microvolt across same resistance" t$ |" M( V0 f9 ]7 d0 R- b/ F
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* F- O0 R6 b$ uDecibel Conversions% x# d& U5 x. O
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dBm = 10 log [Signal (mW)/1mW]) U; t! t. q' G: U. h
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Decibels relative to one milliwatt
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6 u" m' ^* D- K- {% a7 ^7 `--------------------------------------------------------------------------------3 {# e. c( j3 ^& G! I8 E
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Decibel Conversions
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dBmA = 20 log [Signal (mA)/1mA]
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+ E: T9 X) _( r5 k0 VDecibels relative to one microamp through same resistance
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; ^7 W* ]2 ~* OPower Conversions/ t5 H/ y( [% E* _% I$ ?' }, l0 v
' r' n. N% @5 `1 K7 \dBm = dBw + 30
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Conversion from dBw to dBm.$ L" s F; ?. s, @/ g
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Voltage Conversions
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# m( S+ u5 B7 DdBuv = dBv + 120
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3 ?- K4 R3 I# x6 ]' nConversion from dBv to dBuv./ ?# k7 B' E: c1 U ]' Y1 @0 o1 I
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Voltage to Power4 Q \1 b" v% n1 R3 ]8 |9 x
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dBm = dBmV - 107
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% T/ ?. b7 G* JWhere the constant 107 is as follows:, T. \) L' m4 n" z* L
* RF systems are matched to 50W, n* `& Y+ V3 J1 G/ ?) B
P = V2 / R
, \, } E0 `: ?/ I/ i% B10Log10[P] = 20Log10[V] - 10Log10[50W]
% ~4 L$ m6 S" F; xV = (PR)0.5 = 0.223 V = 223000 mV w: m+ t$ L# t/ d0 A- O5 E
For a resistance of 50W and a power of 1 mW:
8 x. n" ?. Z! {: f! J4 W$ v! j20Log10[223000mV] = 107 dB + \1 G! y3 X5 g% N; l& T
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Power Density
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dBw/M2 = 10Log10[V/M - A/M]
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9 K# A# u* R/ G" V' m4 R/ }- k8 G9 K5 WDecibel-Watts per square meter.
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( m6 i- Y7 k: p N5 a% I: ePower Density/ m5 J! g7 o/ H" ]' \% v# S- a
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dBm/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:7 C; ^0 G* S- h. A/ d
10Log10[1000] = 30" x3 F7 C! ?! ]# S6 l7 S3 g2 I
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Conversion Units o( n: z" C: ?3 `/ Y3 r' e
dB = decibels (Log10)
5 m, [- a+ d2 }4 P' [0 v' Q" qu = micro = 10E-6
d8 {. F v; J: lm = milli = 10E-39 H+ W5 U: u0 u- p+ U
dBw = decibels relative to one watt
+ `5 ?$ c+ h7 ?: g% a" u( K5 {dBm = decibels relative to one milliwatt
6 Z( |7 f2 @/ K0 c ydBV = decibels relative to one volt
( V" o- K) l; X' w$ g3 KdBuV = decibels relative to one microvolt
' h2 v& e" I& D, h' HdBuA = decibels relative to one microamp" q9 K4 [8 j: {$ o2 _9 i
V = Volts/ K9 F* ?, i% f* G
A = Amps$ t6 r8 v# m( x' W1 H
I = Current
0 ^/ M' B2 \( yR = Ohms (50)3 h. w8 h. G4 X; @( g; e
W = Watts) P; y; } a8 ^ R) h
P = Power
7 e4 e7 _: @! J' VM = Meter |
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