Author Topic: 50MHz antenas for Handhelds?  (Read 6364 times)

Offline Greekman

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50MHz antenas for Handhelds?
« on: January 20, 2015, 03:33:03 PM »
So... I had a look at the Diamond antenna website and found 4 models
http://www.diamond-ant.co.jp/english/amateur/antenna/ante_3hand/ante_hand1.html
http://www.diamond-ant.co.jp/english/amateur/antenna/ante_3hand/ante_hand2.html

question is what are the negatives/compromises with the 3 band HT antennas?

Offline Carl

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Re: 50MHz antenas for Handhelds?
« Reply #1 on: January 20, 2015, 04:17:07 PM »
But a 5/8 wave Two meter antenna IS a 1/4 wave for 6 meters.The problem is that they are really a bit long and put a good bit of stress on the radio/antenna connector. The 6 meter antenna that came with my Yaesu VX5 HT was less than 10 inches long but was very ineffective for 6 meters and the balance of the antenna was off as the radio body was way too short also. SIZE DOES MATTER with antennas.

Offline Greekman

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Re: 50MHz antenas for Handhelds?
« Reply #2 on: January 21, 2015, 12:28:08 AM »
I see..thanks

Offline Carl

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Re: 50MHz antenas for Handhelds?
« Reply #3 on: January 21, 2015, 04:38:09 AM »
I see..thanks

Don't give up on your project just understand it is less effective to use a 10 inch antenna than a 54 inch tall long whip. Ant that the radio,as a portable,has way too small a body to act as 'ground' for either antenna. I have worked stations as far as 2500KM with just that poor combination...but locally the two meter or UHF was far more capable.

Offline SCWolverine

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Re: 50MHz antenas for Handhelds?
« Reply #4 on: January 21, 2015, 05:04:43 AM »
not worth much, but my new Wouxun 5D's (2m/6m) came with a pretty long (13 1/2") antenna.  Haven't had a chance to really fool with them yet.

Offline Carl

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Re: 50MHz antenas for Handhelds?
« Reply #5 on: January 21, 2015, 05:16:12 AM »
not worth much, but my new Wouxun 5D's (2m/6m) came with a pretty long (13 1/2") antenna.  Haven't had a chance to really fool with them yet.

I would love to hear your 2/6 comparison on simplex communications. I love 6 meters , but it really requires more antenna than is convenient for portable use.

Offline Greekman

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Re: 50MHz antenas for Handhelds?
« Reply #6 on: January 21, 2015, 06:13:05 AM »
50 cm is not that bad uf it is somewhat flexible.

I was thinking about the 6m for recce/security ops in terrain

Offline Carl

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Re: 50MHz antenas for Handhelds?
« Reply #7 on: January 21, 2015, 06:45:41 AM »
50 cm is not that bad uf it is somewhat flexible.

I was thinking about the 6m for recce/security ops in terrain

The possibility of better signals in terrain is only possible with near full size(and fully grounded) 54 inch or so antenna and counterpoise. SIX meters is better in terrain if all other factors are equal,as in antenna/ground/power ,though power is not as big a factor as antenna/ground ..here is a bit about others' attempts.

http://www.eham.net/ehamforum/smf/index.php?topic=74019.0

I wish it were so easy ,but RF just does not go through earth very well.

Offline Greekman

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Re: 50MHz antenas for Handhelds?
« Reply #8 on: January 21, 2015, 02:38:34 PM »
couldn't one gain soem advantage by having a full blown comms station in 6m?

Offline Carl

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Re: 50MHz antenas for Handhelds?
« Reply #9 on: January 21, 2015, 03:11:01 PM »
couldn't one gain soem advantage by having a full blown comms station in 6m?

Without the band being open,6 meters will transmit 5 to 10 percent farther than 2 meters on a 1/4 wave ground plane for each station. That can easily be outdone by a directional beam on 2 meters , and though you can get a directional antenna for 6 meters ...the cost and size is forbidding. A simple HF station will easily out-distance the 2 and 6 BUT not with local ground wave signals...it takes careful antenna design to talk as close as 200 miles on HF , while distance is easy...except for the novelty of talking to other countries...there is limited utility in HF for preppers.

OK ,the utility thing is just my opinion, but I am not driving 2000 miles to help a guy with a flat tire.

Offline Greekman

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Re: 50MHz antenas for Handhelds?
« Reply #10 on: January 22, 2015, 01:15:39 AM »
so what I take from this is.
6 (& 10 meters) are to be used more like HF than VHF.

Offline SCWolverine

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Re: 50MHz antenas for Handhelds?
« Reply #11 on: January 22, 2015, 04:42:36 AM »
in the last episode Jeremy spoke of using 6m FM for a 'race' that was in 'terrain' and that 6m outperformed 2m FM in that situ.
I've been told that 'back in the day' our local club used 6m (for a golf challenge) vs. 2m; but I'm thinking this was before the 2m repeater days?  I personally don't know enough Not to try it as you mentioned (GreekMan) so I bought 2 of the Wouxun HT's to give it a go...Carl is dead on the antenna...4.5' for a 1/4 wave

Offline Greekman

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Re: 50MHz antenas for Handhelds?
« Reply #12 on: January 22, 2015, 04:53:34 AM »
thanks for the reference, i downloaded everything

Also, I voted for a 6-10m special in your survey.
And it woiuld be useful to add a sigline with some links...

Offline SCWolverine

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Re: 50MHz antenas for Handhelds?
« Reply #13 on: January 22, 2015, 05:48:08 AM »
great idea!  ;)

Offline Alan Georges

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Re: 50MHz antenas for Handhelds?
« Reply #14 on: January 22, 2015, 07:02:01 AM »
Also, I voted for a 6-10m special in your survey.

That would be an interesting topic.  This no man's band between pure HF/skywave and VHF/line-of-sight behavior is weirdly interesting.  I'd like to hear more on how people use it.

Offline SCWolverine

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Re: 50MHz antenas for Handhelds?
« Reply #15 on: January 22, 2015, 07:21:10 AM »

Offline Carl

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Re: 50MHz antenas for Handhelds?
« Reply #16 on: January 22, 2015, 07:25:14 AM »
That would be an interesting topic.  This no man's band between pure HF/skywave and VHF/line-of-sight behavior is weirdly interesting.  I'd like to hear more on how people use it.

I had a man in heavy German accent ( YEP,he was in East Germany)tell me I should chat with my friend ,OFF of the 6 meter call frequency...then he decided to ask for a contact when I cleared off...so many think 6 and 10 meters are for DX ONLY....I denied his request.

I would like to hear what utility is being done on 6 or 10 meters as I am kinda' tired of being 'worked'

Offline Carl

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Re: 50MHz antenas for Handhelds?
« Reply #17 on: January 22, 2015, 08:31:52 AM »



I would be interested in practical use of ground wave with 6 and 10 meters for local communications,
and the polarization effects with surrounding tree/buildings with concerns to semi portable (off vehicle antenna)and portable
stations (on vehicle antenna).Also the viability of pocket portable 6 and 10 meter with compromised antennas and ground (antennas you can walk with)


In a random quote from an old USMC Antenna manual:( PM email address for PDF of the old gem of a manual)

Polarization Requirements for Various Frequencies

At medium and low frequencies, ground wave transmission is used
extensively, and it is necessary to use vertical polarization. Vertical
lines of force are perpendicular to the ground, and the radio wave
can travel a considerable distance along the ground surface with a
minimum amount of loss. Because the Earth acts as a relatively
good conductor at low frequencies, horizontal lines of electric force
are shorted out, and the useful range with the horizontal polarization
is limited.
At high frequencies, with sky wave transmission, it makes little difference
whether horizontal or vertical polarization is used. The sky
wave, after being reflected by the ionosphere, arrives at the receiving
antenna elliptically polarized. Therefore, the transmitting and
receiving antennas can be mounted either horizontally or vertically.
Horizontal antennas are preferred, since they can be made to radiate
effectively at high angles and have inherent directional properties.
For frequencies in the VHF or UHF range, either horizontal or vertical
polarization is satisfactory. Since the radio wave travels
directly from the transmitting antenna to the receiving antenna, the
original polarization produced at the transmitting antenna is maintained
as the wave travels to the receiving antenna. If a horizontal
antenna is used for transmitting, a horizontal antenna must be used
for receiving.

Advantages of Vertical Polarization

Simple vertical half-wave and quarter-wave antennas provide
omnidirectional communications. This is desirable in communicating
with a moving vehicle. The disadvantage is that it radiates
equally to the enemy and friendly forces.
When antenna heights are limited to 3.05 meters (10 feet) or less
over land, as in a vehicular installation, vertical polarization provides
a stronger received signal at frequencies up to about 50 MHz.
From about 50 to 100 MHz, there is only a slight improvement over
horizontal polarization with antennas at the same height. Above 100
MHz, the difference in signal strength between vertical and horizontal
polarization is small. However, when antennas are located
near dense forests, horizontally polarized waves suffer lower losses
than vertically polarized waves.
Vertically polarized radiation is somewhat less affected by reflections
from aircraft flying over the transmission path. With horizontal
polarization, such reflections cause variations in received signal
strength. An example is the picture flutter in a television set when
an aircraft interferes with the transmission path. This factor is
important in areas where aircraft traffic is heavy.

When vertical polarization is used, less interference is produced or
picked up from strong VHF and UHF transmissions (TV and FM
broadcasts) because they use horizontal polarization. This factor is
important when an antenna must be located in an urban area that
has TV or FM broadcast stations.
Advantages of Horizontal Polarization
A simple horizontal half-wave antenna is bidirectional. This characteristic
is useful in minimizing interference from certain directions.
Horizontal antennas are less likely to pick up man made interference,
which is ordinarily vertically polarized. When antennas are
located near dense forests, horizontally polarized waves suffer
lower losses than vertically polarized waves, especially above 100
MHz. Small changes in antenna location do not cause large variations
in the field intensity of horizontally polarized waves when an
antenna is located among trees or buildings. When vertical polarization
is used, a change of only a few feet in the antenna location may
have a significant effect on the received signal strength.