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- เผยแพร่เมื่อ 5 ก.ย. 2020
- Let’s compare a quarter wave whip with a half wave whip on 2 metres FM.
Check out these other channels too:
/ ianxfs - Ian / ianxfs
/ @zl1bqdroly / Roly ZL1BQD
/ radioprepper - Gil / RadioPrepper
/ @mattdixon5299 - Matt Dixon / 2E0MLD
/ hollyend01 - Mike / Hollyend01
/ @m0szt - Carl / 2E0EZT
/ m0mcx - Callum / DX Commander
Interesting. I find that having the antenna at the back makes it directional. Maybe a better test would be to use one mag mount in CENTRE of car and manually swap the whips over. Would be also interesting to see the locations plotted out on a map with orientation of car on map. As with many experiments, leads to further experiments and more questions.
An interesting comparison test Tim. I'd love to see this continued to get a more full picture. Your theory of angle of radiation could well be a factor here. Is there a possibility that the spacing of the aerials meant they may becoming array elements to each other?
Good question! I might redo this test but with one antenna at a time 73
Nice one Tim, a good easy to follow video with plenty of information. = )
Thanks Theo!
I use a 7/8 whip on two for even more gain. It is a monoband antenna. Paul G4IJL (for 70 Cms I use a treble 5/8 mobile antenna)
Thanks Paul that’s a useful insight. 73
@@timg5tm941 The ground plane is also the hidden part of the verticle. I use a tripod to mount the whip at a base height of six feet the base is screwed into a SO-239 bolted to the tripod and thus well grounded. I also use low loss UR67 coaxial cable and 'N' connectors. I run a portable station not mobile as its safer on the road.
It is always interesting to see" in the field testing" .
I cant help wondering if the results would change with the antenna mounted in the center of the car roof each time for a more accurate comparison.
The placement on a vehicle can radically change the pattern in my experience.
I think in retrospect you might have a point there Adrian. Although the only thing to add is that the 1/4 wave didn’t exhibit any better performance in any direction.. including that where the majority of the car roof faced towards. I think I’ll consider trying this again in future with a local net to give me time to switch around the antennas.
A colinear mobile antenna (one which is longer than a quarter wave) achieves its gain by lowering the angle of radiation, which can be detrimental in a mountainous region like we have here in western North Carolina. (Elevations from 2000 ft to 5000+.) I've found that a quarter wave antenna is often superior to a common 5/8 wave antenna due to the higher radiation angle of the quarter wave which is able to get over the mountain tops and fill in the space behind it. Plus, the higher radiation angle of the quarter wave is better able to hit the mountain-top repeaters. -- N4SM (Mike)
Interesting bit about 1/4 patterns versus 5/8 wave
Surely lower angle of takeoff is the same regardless of the difference in range. The half wave takeoff angle for the longer range would be nearer the quarter wave angle. Fankly I do not know the relative plots of the two antennas but in may be useful to overlay one over the other and see a comparison.
When I drove around a few years ago on two meteres I used a seven eights Co-linear. Home bound at the mo.
Nice upload Tim.. :)
Thank you sir!
A very informative video Tim, I love to see real world testing and (surprising) outcomes like these. It would be interesting to know the placement of the magmounts on the car roof, as I'm wondering if the aerial location on the roof was a factor in the differing signal reports. Also to add to this to be able to identify contact (rough) locations to get an idea of the radiation patterns involved?
Not sure if it's possible to do a similar test with a 1/4 wave magmount vs a 1/4 wave/groundplane antenna on a pole off of the car, in that this would show where the car body may provide any signal directivity over an 'ideal/free standing' 1/4 wave, especially at 2m and 70cms?
In my younger days on the 11m band, we would set up 1/4 whips on each side of the car to see if it provided any directive 'gain', but it was long ago and not very scientific.Keep up the great vids, 73 Col :)
colin campbell Thanks Col! Some food for thought here 👍 73
I'm pleasantly surprised Tim. I'm contemplating upsizing the car antenna to something larger for static mobile use, but I'm less sure it's worth the expense now. I get a claimed 3db gain on 2, and 6db on 70 with the Diamond nr770. Guess a small Yagi on a pole is the way to go?
Sounds like a great idea
Good test Tim great for new hams 73
Thanks Andy 73
Great video... maybe next time you can set up a camera at the receiving station so we can hear your transmission and see the signal meter.
Now that’s a very good idea indeed. I might do this test whilst out portable but with the signal recorded at home. 73
Radiation pattern and with a bar display it might show the same, but a meter will drop, maybe slightly, but it will, the distant stations could still be heard, but weaker, so less was being received by the antenna though the bar display stayed the same. Not a big enough drop for the display to drop, plus it was at its last bar, so if it dropped it would be telling you it was receiving nothing, which wouldn't be true either! However, if you listen to the signal, it tells you it is not the same strength you are receiving. Just saying! :-I
Would there be any difference between 1/4 wave antennas? A micro magmount with RG213 vs a standard-sized magmount with RG58. Does magmount size come in to play at all? I was thinking about the capacitance to the car body. Or is it not a factor at 2m?
Hi Nick. On 2m little difference in terms of mag mount size. All things equal, a 1/2 wave has a slight advantage over a 1/4 wave. 73
If you used the same mag mount position for each report I would have bought the test. Two mag positions just dosen't make any sense.
👍👏👏
Sirio link please Tim?
Here you go Douglas: www.moonraker.eu/sirio-hp2070h-vhf-uhf-mobile-antenna-dual-band-2m-70cm
This "test" is as misleading as it can be... magnets random placed on a car doesnt tell anything about the antennas solely, it just shoes how the entire setup worked at the time of the recording.
As misleading as it can be? Interesting if somewhat sweeping judgement friend.
@@timg5tm941 Well.. The heading says "antenna shootout"... But the different results you are getting does not depend solely to the antennas in use, but also what they are used for an mainly the mounting and placement on the car.... Testning antennas solely is a completely different ballgame 😁
Thanks for the interesting video Tim. I like these videos about 2m as that's the only option I have at present until i take the plunge and drain my bank account :-)
2m down here in Cornwall is pretty good i think. Not many repeaters but certainly quite lively at times. I would like to get a reasonably decent VHF/UHF setup for use at home and mobile use, and will then look at the antennas you have mentioned. Many thanks again.
73 M7YYZ
Thanks Nik! 73