Wednesday, June 12, 2019

LF receiving antennas

Digital modes and new amateur allocations have caused an upsurge of interest in the radio spectrum's low frequencies. Even if you won't wish to transmit, listening and decoding signals can be an interesting pastime. As an example, here is a recent example of LF signals being decoded on WSPR across the United States. 

It's not too hard to set up a receiver. You could make an upconverter to an HF receiver. Some also find that computer sound cards can receive signals at very low frequencies. 

Then there's the question of what antenna to erect. Unlike transmitting high efficiency is not important. You can be thankful for that because it means that you can make LF receiving antennas quite small. What is important though is good signal to noise ratio. The ability to null out local noise (if it comes from one direction) is one reason that people often use loops for LF and VLF receiving. 

Some ideas on LF antennas and techniques are presented here:

* LF articles from the ARRL

* ON7YA on 136 kHz antennas

* VE7SL 10 foot receiving loop

* W4DEX LF page

PS: Want to get more from amateur radio? This book can help. Available in electronic and paperback form, exploring the facets suggested will keep you entertained for hours. Find out more at vk3ye . com or search the title on Amazon. 

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