| |
G0FTD > ANTENA 01.01.05 16:35l 63 Lines 2725 Bytes #999 (0) @ WW
BID : A39151G0FTD
Read: DL7NDF DG8DG GUEST OK1VKZ
Subj: Re: Antennas and why?
Path: DB0FHN<DB0CL<DB0PDF<DB0WHV<DB0SM<DB0EA<DB0RES<ON0AR<7M3TJZ<ZL2TZE<
GB7YFS<GB7CIP<GB7SXE
Sent: 050101/1416Z @:GB7SXE.#38.GBR.EU #:17886 [Hastings] FBB7.00i $:A39151G0FT
From: G0FTD@GB7SXE.#38.GBR.EU
To : ANTENA@WW
VK3ABK wrote:-
>Recent bulletins got me thinking about antennas and what they are supposed
>to do.
Do you mean you still don't know ?
>Below, is part of a bulletin (I won't credit the sender, to save
>embarrasment) that is a good place to start for a look at 'Current
>Affair'!
Oh you mean my bulletin...
So what's embarrasing about having you agree with everything I've said ?
Oh I see, having an aussie agree with me on packet could well be
embarrasing...yes I can feel the kudos amongst my fellow UK packeteers
going down worse than a drunken prostitute.
>The diagram on the left is original; I have added the bit on the right.
>As you can see, it represents the same antenna but eliminates the
>'strange' 18,000 Ohm impedance at the mid point.
Nothing strange about 18 Z, it's just acting as a switch to open
circuit the top and create the "current situation" I desire to shift the
radiation pattern around.
³ ³
³ The 100 æH inductor equates ³
Ü Ü ³ to more than 18kê at 29MHz ³
³ ³ ³ and so becomes a very high ³
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÁ((((ÁÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ : impedance in a low impedance :
³ 100 æH ³ ³ loop. ³
³ ³ ³ ³
³ ³ ³ The 'loop' now shown as two ³
³ ³ ³ 'vertical' radiators, fed ³
³ ³ ³ out of phase, which radiate ³
³ 2.4m square loop ³ ³ a differential of the energy. ³
³ ³ ³ ³
³ ³ ³ This has also caused a shift ³
³ ³ ³ in directivity. ³
³ ³ ³ ³
³ ³ ³ ³
³ ÚÄÄ¿ ³ ³ ÚÄÄ¿ ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´B1ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ´B1ÃÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
ÚÄÄÄÁÄÄÁÄÄÄ¿ ÚÄÄÄÁÄÄÁÄÄÄ¿
³ A T U ³ ³ A T U ³
ÀÄÄÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÙ
Why not just use a switch anyway you may ask ?
Well I can think of several good reasons - when you have "thinked" about
them (sic) come back and let us all know - we're all waiting.
- The Packet Alternative -
Read previous mail | Read next mail
| |
