Friday, April 12, 2019

Antenna ideas for the 160 metre (1.8 MHz) band

160 metres (1.8 MHz) can be a tricky band for antennas. In fact it's a band that many (most?) amateurs don't bother with due to the space many antennas require. Because basic 'building block' full-sized antennas are massive. For example a half wavelength dipole is 80 metres long. And a quarter wavelength vertical is 40 metres high.  For this reason, unless you've got plenty of space your antenna will need to be significantly smaller. While that compromises performance, you're probably in the same boat as most others on the band. And unless you are in a very remote location contacts should still be possible on the band.

Whereas on bands like 40 metres a half wavelength dipole is almost guaranteed to give good results, greater thought is required for 160 metres. This is not only due to space constraints but where you wish to work. This is because 160 metres supports both ground and sky wave propagation. That's different to other bands where 99% of contacts are skywave and an antenna's groundwave characteristics can be almost safely ignored.

Look at what the AM broadcast stations use. They aim to maximise groundwave coverage within their 50 - 200 km service area. For that they use vertically polarised antennas. So should you if that's your aim, for example if you enjoy local chatting around town or across a bay near you. While your first reaction might be to use VHF for that, 160 metres can also be suitable and is particularly enjoyed by those who use AM.  Good antenna choices include a vertical, or if you want a bit of everything, an inverted-L. You can even use antennas that look horizontal (like a flat top horizontal dipole for 80 metres) as a vertical if you tie the feeders together and load against all the radials you can roll out.

What if you live (say) 200 - 300 km out from a main population centre? They're still good distances for the 530 - 800 kHz end of the AM broadcast band and also our amateur 630 metre band. But they're long for groundwave coverage above 1 or 1.5 MHz.  You can still span those distances on 160m but it will need to be at night employing skywave. The antenna polarisation doesn't matter very much. But you do want the radiation angle to be fairly high. A horizontal dipole, inverted-vee or end-fed wire at any practical height should be fine for that.

What if you want DX? Yes, you can work 10 000km plus DX on 160 metres, though it requires more patience than on easier bands like 40 metres. But it is desirable to have a low radiation angle. A vertical with a good ground system (like we used for local communication) should be OK. But, unless it's very high, a horizontal dipole is unlikely to be.

The above paragraphs settle it. Unless you wish to work some immediate distances then your antenna will likely be some form of vertical (or inverted-L). With as good a ground system as you can manage. And if you're seriously into DXing and you find noise a problem then a separate antenna for receiving is desirable as well.

Below are some ideas on antennas for 160 metres.

* Inverted L by W1FB
M0MCX inverted L for 160 80 40m
* W8NX space-efficient dipole (pdf)
* VK3ZZC 160m vertical
* 22 different wire antennas for 160m
A 160m antenna for a small backyard
PA1M 80 & 160m antenna for the small garden

Have you had experience with these (or other) antennas for 160m? If so please let us know what worked and what didn't in the comments below.

PS: Want to get the most from low power amateur radio? You need Minimum QRP. It covers the equipment, antennas, operating and strategy you need to succeed with QRP. It's available as an ebook or paperback and has been favourably reviewed.

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