Return to KLUBNL.PL main page

rsgb_lf_group
[Top] [All Lists]

Re: VLF: Resonate the antenna, or not?

To: [email protected]
Subject: Re: VLF: Resonate the antenna, or not?
From: Piotr Mlynarski <[email protected]>
Date: Thu, 24 Mar 2011 03:27:38 +0100
In-reply-to: <[email protected]>
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <BF4A524700075746A6467658DFC7102C88B2129D4C@ICTS-S-EXC2-CA.luna.kuleuven.be> <000b01cbe622$6a23f8d0$8d01a8c0@JAYDELL>,<[email protected]> <BF4A524700075746A6467658DFC7102C88B2129D4D@ICTS-S-EXC2-CA.luna.kuleuven.be>,<[email protected]> <BF4A524700075746A6467658DFC7102C88B2129D51@ICTS-S-EXC2-CA.luna.kuleuven.be> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
User-agent: Thunderbird 2.0.0.24 (Windows/20100228)

Stefan Schäfer pisze:
Wow, nice!

Rik/ON7YD, now its your turn again: What will be the ERP when running 100A in that wire? I think 100A is realistic on such a wire. Skin depth should be 0.9 mm. So the effective conductor area 19 mm^2. Assuming 20m x 30m (?) wire (=600m^2) means 100m length, so R ~ 0.15 Ohm. So Scott gets 100 A rms when running 1.5 kW into the antenna (no problem for the mains), without having problems of winding a large coil, without resonating, without ferrite parts, without high voltages (but high currents ;-) ). Am i right, Rik? And what is the ERP? I could take a look on your website but you can do it so well here! What is the L and Z and so the needed voltage to get 100A? :-) Instead of standard FETs, some IGBTs could be used, shouldn't be a problem at 9 kHz and some 100V. Any recommendations? :-)

Scott, what FETs do you use in your design? The IRFP460 is OK for 20 A but not much more. One could do the effort and switch 4x 10 of them in parallel but you'll need a good driver, maybe IXDD430... Interesting stuff!

73, Stefan EI/DK7FC

Hi Stefan,  LF group

Just before i was going to switch off my computers and go to bed your mails arrived ....
below my quick calculations   / Rik , pse, check it out :)  /
Al wire diameter 6.5 mm length 100 meters, f= 8970 Hz
skin depth: 0.925 mm   so Rac @ 8970 Hz  = 0.174 Ohm
20m x 30 m rectangular loop - its inductance L = 162.85 microHenry /RA9MB equation/ radiation resistance Rrad = 0.008994 microOhm / or using picoOhms as in recent examples 8994 pOhm/
2*pi*f*L = 9.178 Ohm
2*pi*f*L/Rac = 52.72

using enough pwr to develop 100 Amp current  TX radiated is 89.94 microwatts
loop over ground i.e. twice the Rad along with -0.39dBd loop gain results in ERP = 164.4 microWatts
Voltage loop around 918 Volt

                                                          73, Piotr, sq7mpj

qth: Lodz /jo91rs/

<Prev in Thread] Current Thread [Next in Thread>