Tuesday, October 15, 2013

The challenges of 80 metre operation from a small garden

Regular readers of this blog will already know that I operate from a small garden. You will all know that this hasn't prevented or deterred me from working DXCC on every band from 80 metres through 10 metres. My lowly Butternut HF6V, which is 26 feet tall, and ground mounted in a corner of the garden near the wall, has enabled me to operate in a limited capacity on 80m. Through last winter, especially as a result of my participation in the CQWW CW contest in late November, I was able to finally get 100 countries confirmed on that band on LoTW.

But I have never been able to enjoy good operation on 80m because the Butternut is too short and therefore limited in what it can hear. It gets out reasonably well for the DX stations, and the low angle of radiation definitely helps.

A photograph of my nested inverted vees, with labels.
Just this week, I decided to put back up the 80m inverted V, off the same feedpoint as the Vees on 30m and 40m. From previous experience, I knew this would involve some serious dog-legging. (For non amateurs, this means making the wire antenna "turn a corner", so to speak, because there isn't enough room for a straight run of wire that's 66 feet long on each leg. One leg - the "reflector" - is able to get a run down along the side of the house, as far as the gate pillar at the front, although about three feet of it still needs to be dog legged.

The other leg - the "transmit" leg - runs down above the back wall of the garden, and then dog-legs up the side wall of the garden to a point at the back wall of the house under the eave. From there, it is dog-legged again by about three feet and tied off. And the mast (insert word "pole" here!) is only 30 feet at the apex.

It's far from ideal, I know. I bet some of you are trying to picture this all in your head and wondering how I've managed to defy the laws of physics, and indeed the laws of effective radiation of RF fields. So how's it working?

The reflector leg of the 80m inverted v dipole runs down
between the houses and is tied off (dog-legged) at a gate pillar.
Here's a summary of the contacts made last night on CW using just 100 watts: PI4EME, US8UX, EI3HMB, HA5OV, IK6DIN, YU9CF, EI6IL, F5TVG/P, HB9FBA, EI7BA, S51FZ, GM3ZLC, EI2EO, UT8MM, G4LEM, PA1MUC and HB30OK. So it's getting out, as far as Ukraine. Hardly a comprehensive test of its abilities, but the reports coming back were generally 579 or 599 or 599 plus! The previous morning, I had worked N8NA on 100w on CW, so that wasn't bad either, but it's likely that he's got bigger antennas than me.

Time will tell if it's up to the job of making more distant contacts. I will run 400 watts when conditions improve and the band quietens a bit - the QRN here can be s9 at times.

Interestingly, the 80/40/30m nested V system also has some resonance on the lower portion of the 160m band. When I say "some", I mean about 3:1 at best, maybe 3.5:1. It might allow me a limited amount of operation on that band over the next couple of months. I may figure out a way to tune it better for 160m. We will see.

In the meantime, I will keep you posted as to the performance of this compromise antenna system.

6 comments:

  1. thanks for sharing, I live in pretty similar environment and you have given me some good ideas, 73 de EI3HXB Martins

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    1. Martins, in my short experience on the bands, it would seem that dog-legging inverted vees is not such a bad thing! I have worked the world on 30m and 40m using those vees. Fantastic stuff.

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  2. Hi we just have to make do with the space we have available and at my old qth i had room for beverages etc but at the is qth i have a 47 - 108 MHz log per on the roof and a 10 meter bazooka dipole inside my attic which at this qth i started over and i am on 99 countries with 5 watts on the inside antenna but i love the challenge 73 David

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    1. That's great going for 5 watts and an attic dipole. Well done! Glad to hear you are enjoying it - that's the main thing!

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  3. Hello Anthony, most amateurs have to deal with small gardens. But I always say: better one antenna then no antenna. if propagation is right you can work the world with this inv-V.You just have to be there on the right time. 73, Bas

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    1. That is so true Bas! You are absolutely right. I have worked some nice DX with that Butternut, including Clipperton and New Zealand!! Perseverance is the key...

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