Magnetic Loop Calculator

Magnetic Loop Antenna Calculator
Magnetic Loop Antenna Calculator

 

Magnetic Loop Calculator v.1.6 by KI6GD

It’s a light magnetic loop antenna calculator that run on MS Windows, and allow to calculate capacitor values and voltage based on Loop circumference, conductor diameter, desired resonant frequency and the operating power.
Works either in Standard and Metric units, and let you choose on material, and  loop shape, as circular, square or octagon.

Does not requires setup or installation, is a simple executable that can be lunched directly.

Download the  loopcalc.exe  for Windows. (12Kb Zipped)

 

Note by PA0NHC

This software should not be used for loops having a larger circumference than 1/10 lambda. The resuls then become faulty. Read his loop article why this software is not valid under that conditions.

 

23 thoughts on “Magnetic Loop Calculator”

  1. Salve buon giorno. Avrei intenzione di costruire una antenna loop magnetica per i 145,5 mhz da utilizzare sul mio portatilino.
    Ho navigato su vari siti ed i programmi che ho trovato per calcolare il loop si blocca sul parametro lunghezza del loop.
    Premetto che il diametro del filo in rame è di 3 mm. Nei programmini non riesco a ricavare la lunghezza complessiva del filo per il loop ed il diametro…
    Gentilmente mi potresti dare una dritta?

    Saluti da Ortisei
    Ilijtsch IN3EBM

  2. Very nice, program, BUT only for 1 – 30MHz.
    If I want to design for 144MHz, where do I start?

  3. Thanks once again Simone. I have found several articles on your website to be of great help. 73’s, Dave 26TW252

  4. I have just started researching magnetic loop antennae for HF and find your article to be very useful.
    Thank you.
    VK5ZWM.

  7. Many thanks – just what I was looking for! A program to confirm my own calculations (I wasn’t ‘that’ far out). Much appreciated Simone. 73’s Lin M0TCF.

  8. Dear Simone,
    Seen your mag loop calculator , thanks for helping Hams !
    My problem is , tried to down load it to my I pad ( apple) but no luck!
    Do you have a version for it?
    Any way , I am thankful to you!
    Kindest Regards ! Merry Christmas and Happy New Year! 73!
    Leonard Fernando.

  11. Hello,
    the results of this software are only correct for loops with a (VERY small) circumference of less than 1/10 lambda. This is due to the fact, that the software supposes, that the RF current around the full circumference of the loop is constant (i.o.w. has everywhere the same value). That is NOT Always true !
    As the RF current in 1/8, and especially in 1/4 lambda circumference loops is NOT constant, the software output for a 1/4 lambda circumference loop is completely WRONG.
    Furthermore : the useablity of the “radiation resistance” is NIL for a loop builder. If he wants to match his loop to a 50 Ohms power source, he needs the loops “feed point impedance”. Which is a completely other value and dependant on the position of the feed point..
    G0CWT found out what the real feedpoint imedance of a 1/4 lambda circumference loop is, its real (far lower) losses are, and its (NON- omni) radiation pattern.
    At my site : http://www.pa0nhc.nl is a detailed description of my 10m circumference loop, perfectt;y matched for 40m and 80m.
    73’s, Nico pa0nhc.

  12. This is a fine calculator but I agree with Alan… I need to calc for antennas in the upper VHF and UHF TV bands (174-216 mhz and 470-700 mhz). Also, I was hoping for a calc to do receiving antennas. This is for transmission only (it asks for operating power in watts), so very limited for many of us. Would we have to input 0.000001 watts for good result?

  13. Hey Jopower – transmit and receive antennas are about the same, aren’t they?
    The “Operating Power” input exists only to calculate the “Capacitor Voltage”. Ignore them both. And maybe if you enter “0” power, it will output “0” voltage.
    For a receive antenna, the tuning capacitor capacitance will be the same, but the voltage rating can be much lower.

  15. Dear Simon ,
    I have seen your loop calculator, thanks!
    Do you ha be a version to use it with Apple I pad? If so where can I find it.
    Kind Regards and 73!
    Leonard Fernando.4S7LF
    Srilanka.

  17. What if I will use 22mm pipe instead of 22mm solid wire? Cross-section surface will be different.

  20. As for the HF orientated range it covers, fair play as most who’d download it want a mag loop (STL for either/dual use) will be looking at a fixed segment HF size design or will take it to the next step as a tunable variant.

    As for upwards of 30mhz, well, any good reference on antennas will give you the formula chain required, just about as easy to knock up in a spreadsheet or as a type-in/output result CLI program in C/Basic/*insert preferred language* interpreted or as a compiled standalone exe. Hell, with C#, you can knock out the equivalent covering a wider range quite easily.

    Just keep in mind, when constructing, once in VHF upwards (especially at UHF upwards) everything you use material wise has notable distinct parasitic potential to start being reflective and absorb notably EM wise and you’ll find that BW becomes much narrower, relative to a proportional relationship between loop section diameter and loop diameter itself, as does the material etc.

    At VHF upwards, I found good results moving away from wire and using large diameter section tubular construction for the loop itself – everything BW wise gets narrower for a resonance when you get into VHF/UHF/SHF RF (as HF people view it, dark magic territory still to this day). My design for 430-440mhz use (70cm orientated to cover up to hotspot/gateway digital use segs as much as TG/SSB) uses 3cm section diameter tubing (made of copper sheet I bent into tube sections) with not horrible overall bulkiness.

    Remember also, where in the loop you put your termination affects it’s polarisation characteristics and overall is a great substitute for a dipole and is barely (if built right) much lower than unity gain (I got one to 99.99% efficiency with a good fixed frequency centre resonance and bandwidth I needed) but the brickwall rejection characteristics off angle are worth a bit of inefficiency easily in our high QRM digital world hell.

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