Re: LF: Re: E field active antennas

[g4gvw@aol.com]

Mal,

With all due respect for your undoubted high opinion of your own professional expertise might I suggest that you perhaps enquire as to Andy's credentials before wasting space/time/bandwidth trying to teach his grandmother to suck eggs.

73 de  Pat g4gvw

-----Original Message-----
From: mal hamilton <g3kevmal@talktalk.net>
To: rsgb_lf_group@blacksheep.org
Sent: Fri, 5 Dec 2008 18:45
Subject: LF: Re: E field active antennas

Try a piece of wire as long and high as possible and an ATU this is superior to any active antenna or loop for that matter, the loop only helps in a noisy environment, and even then not always. 
G3KEV 
 
----- Original Message ----- From: "Andy Talbot" <andy.g4jnt@googlemail.com> 
To: <rsgb_lf_group@blacksheep.org> 
Sent: Friday, December 05, 2008 4:22 PM 
Subject: LF: E field active antennas 
 
> Having just had to make an active antenna for HF (for gainful 
> employment-type work, not Am. radio purposes. The commercially made 
> one we've ordered is on five weeks delivery and it was needed before 
> yesterday) I was wondering about a helical element. 
> 
> As the thing had to be resonably lightweight, I made the antenna 
> element from copper tape on 15mm plastic water pipe rather than use a 
> solid copper tube. Just for a bit of novelty I wound the tape in a 
> helix, but then started wondering if doing that would make any 
> difference to performance. Normally, helically winding an antenna 
> (rubber duck type at V/UHF) only serves to distribute loading 
> inductance into a short antenna to make it resonate - unlikely to 
> change improve the loss terms at all. But I did wonder if the added 
> extra inductance, or increased conductor length (not element length - 
> that is 1.2m) would change the performance significantly from a 
> straight tube. 
> 
> Does anyone have any ideas - food for thought if nothing else? The 
> base amplifier is one I've used several times before for V/LF up to HF 
> based around a J310 source follower running at 20mA with bootstrapped 
> input followed by a 2N5109 emiter follower at Ic = 80mA. I may have 
> published it way-back-when in the amateur press in the 73kHz days. 
> Not the best design judging by some of those published in more recent 
> years, but did mean all the components were to hand for an instant 
> job. 
> 
> Andy G4JNT 
> www.scrbg.org/g4jnt 
> 
 
-------------------------------------------------------------------------------- 
 
 
No virus found in this incoming message. 
Checked by AVG - http://www.avg.com 
Version: 8.0.176 / Virus Database: 270.9.14/1831 - Release Date: 12/4/2008 9:55 PM 
 

---

AOL Email goes Mobile! You can now read your AOL Emails whilst on the move. Sign up for a free AOL Email account with unlimited storage today.