Antenna Length

[rocky28965]

I have a Nagoya NL-144P wip antenna mounted on my roof.
It receives amazingly well on VHF Airband, which supprised me as it's tuned for 144Mhz - 174Mhz
Airband in this part of the world is 116Mhz - 136Mhz
From the Nagoya specs, the current length of the wip is 570mm
I was wondering if it would work better or worse if I inceased the length to 600mm.
I would have to source a wip of that lenght to try it, so thats why I am asking the question.
Thanks

 

[doctordialtone]

I would have to source a wip of that lenght to try it

I think you're close enough to the proper length - especially since the antenna is already in place.

Any improvement will be minimal.

Good luck.

 

[ka3aaa]

if it works why play with and mess it up.

 

[mmckenna]

If you really felt the need to try it, and experimentation is certainly part of the hobby, try using a length of metal coat hanger. Just make sure you sand/scrape off any of the coating on it. It'll be an easy test to see if it makes a difference. I doubt you'll see much, though. Looks like a 1/4 wave design on 2 meters, and quarter wave antennas are quite broadband.

 

[rocky28965]

Well that's why I asked the question and now I know the answer, so I'll leave it as is.
Thank you all for the replies.

 

[vu2nan]

I have a Nagoya NL-144P wip antenna mounted on my roof.
It receives amazingly well on VHF Airband, which supprised me as it's tuned for 144Mhz - 174Mhz
Airband in this part of the world is 116Mhz - 136Mhz
From the Nagoya specs, the current length of the wip is 570mm
I was wondering if it would work better or worse if I inceased the length to 600mm.
I would have to source a wip of that lenght to try it, so thats why I am asking the question.
Thanks

A ¼ λ ground plane antenna or a ½ λ J-Pole antenna, cut for 125 Mhz, would make a big difference.

Regards,

Nandu.

 

[majoco]

I watched 'flightradar24' and followed a few flights from home until they descended into Auckland, Napier or Christchurch. I didn't work out the distances but I was very pleased with my coverage from a folded dipole cut for 125MHz - it's only about 3 metres off the ground. I don't know how many people down your way are receivers for FR24 but you can have a look and see where you lose signal. I recall that you are in Wanaka so your physical horizon is quite high which might reduce your reception - if the aircraft has gone over the horizon no antenna will receive a signal much beyond that, regardless of whether it's tuned, untuned or a bit of wet string.

 

[jwt873]

For the metrically impaired -- 570 to 600mm is an increase of 30mm or 1.18 inches. For transmitting, that would be a fairly significant change, but for receiving I can't see it making any difference at all.

FWIW, our airport is 50km away over flat land. I hear it OK using a dual band 2m/70cm antenna mounted on top of a 12 meter tower.

 

[Ubbe]

For transmitting, that would be a fairly significant change, but for receiving I can't see it making any difference at all.

An antenna element behaves exactly the same at both receive and transmit. The only difference are that when you transmit into a detuned antenna you get SWR back to the transmitter that could damage it if it doesn't have any protection for it, like a current limit circuit.

Everything like groundplane and lenght of elements and there angle are as important to the signal level regardless of which way the electromagnetic energy travels.

/Ubbe