[OZAPRS] Newb HF questions ;)
David and Justine Olsen
davejust at bigpond.net.au
Sun May 24 12:54:56 EST 2009
Well my 1/4 wave is closer to 1/2 meter
On 24 May 2009, at 10:09, Craig Turner wrote:
> Hmm,
>
> Actually the standard VHF antennas on the aircraft I fly are about
> the length of a knitting needle. Are the V shapped horizontal
> antenna often found on the empennage a diploe? I had thought they
> might be as there is one element either side of the empennage?
> Actually those ones look more like wire coat hangers than knitting
> needles
>
> Craig
> VK3LCT
>
>
>
> David and Justine Olsen wrote:
>> No but I did think to myself, that is a short dipole for 120 MHz-
>> I am a pilot.
>> On 24 May 2009, at 08:10, Ray Wells wrote:
>>> Ben,
>>>
>>> Nope, not a knitter, but my wife is.
>>>
>>> Didn't anybody spot my "mistake"?
>>>
>>> If one needle when used as a quarter wave, and the frequency is
>>> 240MHz, two of them used as a dipole will still be 240MHz, and
>>> not 120MHz.
>>>
>>> Ray vk2tv
>>>
>>> Ben Lindner-VK5JFK wrote:
>>>> Well done Ray. Were you a knitter from way back ? having those
>>>> needles hanging around. Not that there is any thing wrong with
>>>> that, a lot of men knit :-)
>>>>
>>>> Ben vk5jfk
>>>>
>>>> Ray Wells wrote:
>>>>> Looks like it's time to get technical, heaven forbid!
>>>>>
>>>>> I've just measured a typical aluminium knitting needle at
>>>>> 300mm. If we assume it is a quarter wavelength and the length
>>>>> to diameter ratio is 0.96 we can divide 300000 by (1200/0.96)
>>>>> to arrive at 240Mhz. This is a reasonably thin needle so an
>>>>> appropriate adjustment needs to be made for fatter needles. The
>>>>> metal end-cap would add slight capacitance to slightly lower
>>>>> the resonant frequency.
>>>>>
>>>>> Since knitting needles are usually used in pairs, a dipole
>>>>> would be resonant at about 120Mhz which is great for the
>>>>> aircraft band.
>>>>>
>>>>> Ray vk2tv
>>>>>
>>>>>
>>>>> Tony King wrote:
>>>>>> I had to ask.... What band are knitting needles resonant on??
>>>>>> Regards Tony VK3API
>>>>>>
>>>>>> Ben Lindner-VK5JFK wrote:
>>>>>>> "Have you thought about trading in your radios for knitting
>>>>>>> needles :-) "
>>>>>>>
>>>>>>>
>>>>>>> Ray, I believe that Scrap Booking and Quilting have taken
>>>>>>> over from knitting now. :-)
>>>>>>>
>>>>>>> Ben
>>>>>>> VK5JFK
>>>>>>> _______________________________________________
>>>>>>> Ozaprs mailing list
>>>>>>> Ozaprs at aprs.net.au
>>>>>>> http://aprs.net.au/mailman/listinfo/ozaprs
>>>>>>> ----------------------------------------------------------------
>>>>>>> --------
>>>>>>>
>>>>>>>
>>>>>>> No virus found in this incoming message.
>>>>>>> Checked by AVG - www.avg.com Version: 8.5.339 / Virus
>>>>>>> Database: 270.12.36/2126 - Release Date: 05/21/09 06:22:00
>>>>>>>
>>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Ozaprs mailing list
>>>>>> Ozaprs at aprs.net.au
>>>>>> http://aprs.net.au/mailman/listinfo/ozaprs
>>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Ozaprs mailing list
>>>>> Ozaprs at aprs.net.au
>>>>> http://aprs.net.au/mailman/listinfo/ozaprs
>>>>> ------------------------------------------------------------------
>>>>> ------
>>>>>
>>>>>
>>>>> No virus found in this incoming message.
>>>>> Checked by AVG - www.avg.com Version: 8.5.339 / Virus Database:
>>>>> 270.12.37/2129 - Release Date: 05/22/09 17:56:00
>>>>>
>>>>>
>>>> _______________________________________________
>>>> Ozaprs mailing list
>>>> Ozaprs at aprs.net.au
>>>> http://aprs.net.au/mailman/listinfo/ozaprs
>>>>
>>>
>>> _______________________________________________
>>> Ozaprs mailing list
>>> Ozaprs at aprs.net.au
>>> http://aprs.net.au/mailman/listinfo/ozaprs
>> _______________________________________________
>> Ozaprs mailing list
>> Ozaprs at aprs.net.au
>> http://aprs.net.au/mailman/listinfo/ozaprs
>
> _______________________________________________
> Ozaprs mailing list
> Ozaprs at aprs.net.au
> http://aprs.net.au/mailman/listinfo/ozaprs
_______________________________________________
Ozaprs mailing list
Ozaprs at aprs.net.au
http://aprs.net.au/mailman/listinfo/ozaprs
More information about the Ozaprs
mailing list