Wednesday, July 10, 2019

Frame antennas for transmitting (multi turn loops)

Don't have much space but want to get on HF? A magnetic loop can be effective. 

A problem in some cases is they need lots of thick heavy metal to be efficient. 

Another approach is to use a longer but thinner conductor wrapped around or supported by a timber frame.  

Efficiency is not necessarily very good but you may still be able to get a signal out, especially if using efficient digital modes like WSPR.  And frame antennas can work very well on receive. 

Here are a couple of 3.5 MHz frame antenna ideas to think about: 

* SM0VPO frame antenna for 80m

* DL1GSJ 80m frame antenna

You would no doubt be able to redimension them for other bands.

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1 comment:

  1. Hi Peter,
    Here is a link to a multi-turn loop calculator:
    It is in Czech but an English version is available by clicking the English flag in the top right corner of the page.

    I've used this calculator to build a 2 turn loop for 40m using LMR400 coax and an MFJ-19 butterfly cap. It works well on my small condo balcony using FT8 and CW.
    Paul VA3ZC


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