sila pole

[Petr Krc]

> "VA Elektronik - Andel Vladimir ing." wrote:
> Nevite nekdo nahodou, kdyz mam vysilac s nejakym vykonem, ktery vyzaruje
> do celeho prostoru rovnomerne, jak v nejake vzdalenosti vypocitam silu
> pole ve V/m? Napadlo mne ze E x H x plocha cele koule, kam energie dopada,
> by se mela rovnat tomu vykonu.

Motorola APPnote AN1705.PDF:
----------------------------
Common-mode radiation or monopole antenna radiation is caused by
unintentional voltage drops that raise all the ground connections in a
circuit above system ground potential. The electric field term for CM is:
E = 4 * 10^-7 * (f * L * If / d)  [volts/meter]
Where:
f  = frequency in Hz
L  = cable length in m
d  = distance from cable in m
If = CM current in cable at frequency fA

Differential-mode radiation occurs when an alternating current passes
through a small loop. The magnitude of the radiation from the loop varies
in proportion to the current. The electric field term for DM is:
E = 265 * (10^-16) * (A * If * f^2 / d)  [volts/meter]
Where:
A  = loop area in m^2
d  = distance from loop center in m
If = current at frequency A in Hz
f  = frequency (of harmonic) in Hz

For example, at a frequency of 100MHz and a distance of 3m, the
electric fields for CM and DM are:
E CM = 1mV/m    @ I = 25uA and L = 1 m
E DM = 220uV/m  @ I = 25mA and A = 1 cm^2

A variation in current through a conductor with a certain inductance L,
results in a voltage drop of:
V = L * di/dt


Dale viz:
http://e-www.motorola.com/brdata/PDFDB/docs/AN1705.pdf

-- 
Regards
           Petr Krc