MAGNETIC LOOP ANTENNA CALCULATOR ONLINE - I CAN´T FIND A SITE

Hi,

it´s Patrik here again (I have to calm down with the posts).

Can someone give me, please, a link to a magnetic loop antenna calculator? I can´t find it.

73s,

Patrik

Hi Patrik,

You keep posting my friend, it's good to see the forum alive apart from the usual call sign requests.

There's several Magnetic Loop calculators about but most seem to be pieces of software you download. The one I used when I played about with such loops is an online calculator available here :-
(plus many other handy calculators!)

https://www.66pacific.com/calculators/small-transmitting-loop-antenna-calculator.aspx


I gave up my experiments as although they are wonderful antennas for their diminutive size they do require constant retuning and were worse performing than a simple wire antenna. If you do experiment rather than trying to purchase an expensive variable capacitor you can make fixed capacitors up with lengths of coax or use a sliding plate or 'book' type capacitor which are very effective. (Homebrew at its best!)

Loads of info on the web and always worth searching many of the 'Non-English-Language' sites that google searches normally spout out.


Keep posting, keep asking, keep playing and never lose that inquisitive nature.  


All the best,
Victor

Thanks Victor!

(As always!)

I will deffenetely make (or buy!) me a variable capacitor, I calculated the value and it said 174 pF for the frequency 14.100 for 20 meters, because I don´t want to take much space with a big dipole (and not as much wire, if not, my parents aren´t going to be very happy  . I already used a lot of wires with my previous antennas for 11 meters: my dipole, my T2LT, a shortened dipole, a ground plane and another dipole, but then I made two 2 meter antennas: a ground plane and a dipole ).

So now you see why I need a small and short antenna, that doesn´t use much wire.

73s,

Patrik

Interesting..

For NVIS HF you'd have to make two Mag Loops for 160m/80m and 60m/40m

Target frequencies would be 1.905 MHz/3.663 MHz and 5.2585 MHz/7.045 MHz

(these are RAYNET HF Calling Frequencies 5MHz is always USB, the rest LSB)

160/80                     60/40
Conducting wire circumference
19.5m                      12.05
Diameter of Conducting wire
2.5 cm                      1.0 cm
Efficiency
32%/82%                 61%/81%
Bandwidth kHz
1.94/10.4                 18.8/45.3
Tuning Cap pF
323/87                     92/51
Cap Voltage RMS
1592/1324               304/262
Circulating Amps
6.16/2.66                 0.922/0.593
Inductance micro henrys
21.6                         9.99

It'd be interesting to have a switch between two tuned capacitors on each antenna to change the calling frequency, but suspect these would have to be pre-tuned tuning capacitors, switched using some sort of diplexer, with each antenna also switched by a diplexer.

It also looks like top band has a decision between antenna % efficiency and conductor wire diameter, a bandwidth of less than 2.5 kHz voice, I'd suggest you'd need at least 3 kHz of bandwidth for SSB Comms to avoid clipping the audio, so this means the efficiency would not get above 22% on top band, giving just one pre-tuned Voice channel using 1.5cm diameter conducting wire.  80m would have its efficiency drop to 74%, but that's the best compromise if you're intent on operating spot frequencies with automatic band switching.

A complicated project, and I'd probably target fixed frequencies for JS8Call or PC-ALE instead of voice communications.

However, I suspect an array of tuned/trapped dipoles is less complicated, or a random dipole on an  SGC Smartuner would be much simpler to build...      umm wait a minute...