V Pole antenna

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Re: V Pole antenna

Post by Ivan on Thu Apr 23, 2015 7:47 am

Hi James,
IMO all that project is an "easy and fast made" antenna for experimenters. It probably will work at once, but it will require some pruning to get optimum results and to make the antenna permanent. The length of the nails, their material (iron? brass? copper?), their diameter (=the diameter of small coils near the feeding point!) surely make certain difference. The wooden base should be dried and then impregnated against moisture.
But even without these precautions it may be good for making fast experiments.

73 Ivan OK1SIP

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Re: V Pole antenna

Post by JamesOB on Thu Apr 23, 2015 7:26 am

Hi Ivan
You may possibly be right. However, you may for instance use pins that are 10 mm long and I may use pins that are 25 mm long. At 430 MHz this does make a huge difference (possibly not so critical at the lower frequencies).
I have for been looking for a simple antenna for 70 cm that is easily and reliably replicated.  This has turned out to be very difficult - dimensions are critical and in the case of Harry's design you will find that the amount of moisture in the wood is also going to play a role.
One could argue 'build it and see' - however, once again, getting reliable SWR measurements is difficult at these frequencies.
73 James ZS1XN

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Re: V Pole antenna

Post by Ivan on Thu Apr 23, 2015 6:24 am

Hi James,
the detuning influence of the pins is probably included in the empirical constant 1.028, that Harry uses. The dimensions of this type of antenna are not extremely critical anyway.

BR from Ivan OK1SIP

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V Pole antenna

Post by JamesOB on Wed Apr 22, 2015 3:55 pm

On the site Harry describes making very simple VPole antennas.

He wraps wires around panel pins which is nailed into wood.

Now, if the wire makes contact with the pins/nails, surely this will affect the length of the wire and therefore the resonant frequency of the antenna? Especially on 70cm even a few mm will be critical?

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