Hi all,
Just a quick question,
I have a 205ft G5RV antenna that I will be using in an inverted V configoration, the center will be @ ~8m so how close can I have the ends from the ground? If they are to close will it cause a problem?
Thanks and best regards,
Kyle...
VK6FKJN
Inverter V question
Re: Inverter V question
Kyle,VK6FKJN wrote:Hi all,
Just a quick question,
I have a 205ft G5RV antenna that I will be using in an inverted V configoration, the center will be @ ~8m so how close can I have the ends from the ground? If they are to close will it cause a problem?
VK6FKJN
Dipoles close to ground radiate a lot of their energy at high elevations, which is great for short distances, and not so good for longer distances.
A further effect is that you will lose more power heating the ground when the wire is close to ground, so higher is better, and less than a few metres increases the ground heating loss markedly.
I am wondering though why you are using a 205' long G5RV.
Anyway, back to your question, 8m at the centre is pretty low, and you should try to keep the lowest part of the wire above 3m for ground loss reasons... but higher is better.
I just did a quick calculation of a catenary for 2mm bare HDC wire with a 30m span, 8m at the high end and 4m at the low end. For survivability of 40m/s winds, you will need a sag of 0.76m, but the lowest point remains the 4m end. So, such a span is feasible... probably not with annealed wire.
Owen
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VK6FKJN
Re: Inverted V question
Hi Owen,
I am using a "WA2NAN True-Talk G5RV 205ft", I assume you are asking why 205ft? Well I got the antenna pre getting my license and it was a bit of a snap purchase
but I have found nothing wrong with it why do you ask?
From your comments it would seem best for the heights i am talking about to configure the antenna as a dipole, 8m - 8m - 8m? With no inverted V?
I will be using this antenna this weekend mobile on the hills in Perth for the upcoming competition and was looking for the best way to set the antenna up etc.
Any advice is most welcomed,
Best Regards,
Kyle...
VK6FKJN
I am using a "WA2NAN True-Talk G5RV 205ft", I assume you are asking why 205ft? Well I got the antenna pre getting my license and it was a bit of a snap purchase
but I have found nothing wrong with it why do you ask? From your comments it would seem best for the heights i am talking about to configure the antenna as a dipole, 8m - 8m - 8m? With no inverted V?
I will be using this antenna this weekend mobile on the hills in Perth for the upcoming competition and was looking for the best way to set the antenna up etc.
Any advice is most welcomed,
Best Regards,
Kyle...
VK6FKJN
Re: Inverted V question
Kyle,
The G5RV is not a good performer on 10m. I expect that the 205' G5RV works on 160m. but at the expense of poor performance on 14MHz. I guess that is not an issue as you aren't licenced for either band, but the dipole is twice the length of the G5RV and for what benefit?
Bigger isn't necessarily better. I recently explained to three chaps on 7MHz in one Saturday afternoon that their 80m halfwave dipole with coax feed would work ten times as well (on 40m) if it was half the size. (Yes, I mean't that literally... their coax feed had loss of 10dB (~10% efficiency) or more in the way that they were using it.) The way I figure it, with a FL, you have only 10% of the power that most people run, there is little point in chucking 90% of what is left away so that you radiate 1% of what most people are using.)
The merit in the Inverted V configuration is that one tall mast can carry the antenna. In a field situation, you often afford to use a long rope at the end of each leg and tether the rope at ground level and the end of the wire will still be several metres above ground, so needing only one mast.
Owen
The G5RV is not a good performer on 10m. I expect that the 205' G5RV works on 160m. but at the expense of poor performance on 14MHz. I guess that is not an issue as you aren't licenced for either band, but the dipole is twice the length of the G5RV and for what benefit?
Bigger isn't necessarily better. I recently explained to three chaps on 7MHz in one Saturday afternoon that their 80m halfwave dipole with coax feed would work ten times as well (on 40m) if it was half the size. (Yes, I mean't that literally... their coax feed had loss of 10dB (~10% efficiency) or more in the way that they were using it.) The way I figure it, with a FL, you have only 10% of the power that most people run, there is little point in chucking 90% of what is left away so that you radiate 1% of what most people are using.)
The merit in the Inverted V configuration is that one tall mast can carry the antenna. In a field situation, you often afford to use a long rope at the end of each leg and tether the rope at ground level and the end of the wire will still be several metres above ground, so needing only one mast.
Owen