[Lowfer] Loop Radiation Resistance

[Bill Ashlock]

Lyle,

>If you use the classic formula for the radiation resistance of a single-=
turn
>loop in free space: Rr =3D 31,200 * (area squared) / (wavelength raised =
to the 4th power)
>and want to calculate the effective radiated power using P =3D (current
>squared) * resistance, you have to add 3 dB to the result because all of=
 the
>radiation is confined to one hemisphere. This correction does not apply =
to a
>ground-mounted vertical, since it has already been taken into account in=
 the
>formulas for radiation resistance. =20

This additional 3db seems to make the SVM numbers that I read for WA matc=
h the std equation for field strength. In other words, I am putting out a=
 signal that is 3db higher than I though I should at 1W. I have some text=
 books including the good one: Antennas, by John Kraus, that do not add t=
he extra 3db for loop antennas. I notice that some of the guys in the UK =
are adding the 3db for other reasons. Are there any textbooks/papers that=
 you have found that explain the 'one hemisphere' effect?  =20

BillGet more from the Web.  FREE MSN Explorer download : http://explorer.=
msn.com


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