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Author Topic: HF from the beach  (Read 2703 times)
M5AEO
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Posts: 265




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« on: November 25, 2011, 03:29:20 PM »

I spent a rather miserable couple of hours on a north Norfolk (UK) beach last week. 
I put up my firbeglass pole with a quarter wavelength of wire and spread out some radials in the sand, connected up to my FT-897 and sat down expecting GREAT THINGs !

I was disappointed: I only worked 5 stations in 2 hours with my 20 watts of SSB before the batteries ran out and I started shivering in the cold wind.  I learned a lot logistics-wise, such as don't do it in November, and sand gets everywhere!

But I really did expect the antenna to perform better than it did.  This was my first portable op using the vertical, and I think my inverted-V dipole used in the past seemed to perform better.

What are your experiences?

Jonathan, M5AEO

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WB6BYU
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« Reply #1 on: November 25, 2011, 04:51:39 PM »

How close were you to the water?

Was the band otherwise open?  Did receive signals sound strong?

I've had good results - sometimes - operating from the shore.  Probably the best was
from southeast Alaska with an antenna strung from a spruce tree out across the tide
flats - I went out at low tide and tied off the end of the antenna with plenty of rope.
(A 20 foot tidal difference is not uncommon.)  Then when the tide came in I had a
sloping long wire over salt water.  Worked KG4 and KZ5 (back when both were DX
prefixes) and a PY with my trusty Argonaut at 2 watts output on Field Day.  On
the south coast of West Australia I worked long path into the eastern US using a
dipole tied across a rock face.

On the other hand, operating from Tasmania I had a great 10m vertical dipole
dangling over the edge of the bay and didn't work anyone.


I use the following rules of thumb for such operating:

1) the antenna has to be close enough to the salt water and/or high enough.
To maximize low angle radiation for DX, I figure that radiation from the antenna
needs to be able to travel downwards at 20 degrees from the horizon and hit salt
water before it hits sand or rock.  For a quarter wave vertical that is measured
from the feedpoint.  For a longer vertical (such as a half wave hanging from a
kite) it is measured from the point of maximum current.  For shorter skip, the
antenna has to be closer to the water so the reflection at the desired angle
is from the water, not the beach.  (And especially not from rock.)  DXpeditions
like to mount their vertical antennas close enough to the water's edge that the
base is actually surrounded by water at high tide.  You may find that raising the
feedpoint up your mast and putting it as close to the water's edge as you can
manage helps to improve your signal.

2)  The band has to be open.  Even the best antenna won't help if there is no
propagation.

3) A vertical over salt water will help a lot for DX, but not nearly as much for
shorter distances that require a higher angle of radiation.

4)  watch the tide.  In Alaska I had my station set up on a plank laying against
a large driftwood log, and I nearly went maritime mobile when the tide came all
the way up to the log and around the end to where I was sitting.
« Last Edit: November 25, 2011, 05:10:05 PM by WB6BYU » Logged
W8JI
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« Reply #2 on: November 25, 2011, 05:02:26 PM »

I spent a rather miserable couple of hours on a north Norfolk (UK) beach last week. 
I put up my firbeglass pole with a quarter wavelength of wire and spread out some radials in the sand, connected up to my FT-897 and sat down expecting GREAT THINGs !

I was disappointed: I only worked 5 stations in 2 hours with my 20 watts of SSB before the batteries ran out and I started shivering in the cold wind.  I learned a lot logistics-wise, such as don't do it in November, and sand gets everywhere!

But I really did expect the antenna to perform better than it did.  This was my first portable op using the vertical, and I think my inverted-V dipole used in the past seemed to perform better.

What are your experiences?

Jonathan, M5AEO



The salt water only helps in the direction of the salt water and mostly on lower bands.

The salt water does not change or fix antenna ineffieciency, it only changes Fresnel region losses.

How good was your antenna and ground system, and was the band open in a direction out over the salt water?

73 Tom
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KG6BRG
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Posts: 119




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« Reply #3 on: November 26, 2011, 06:34:09 AM »

I have good luck usually just with a horizontal random wire and a counterpoise of course you need a tree or something to attach the far end of the antenna wire but I have found just a couple of meters above ground is fine, at least on 40 meters. 
I agree, the beach with all the sand is a poor environment for radio gear. I like parks and lakeshore for portable ops.  Cheers Scott.
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KE3WD
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Posts: 5689




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« Reply #4 on: November 26, 2011, 09:01:32 AM »

I spent a rather miserable couple of hours on a north Norfolk (UK) beach last week. 
I put up my firbeglass pole with a quarter wavelength of wire and spread out some radials in the sand, connected up to my FT-897 and sat down expecting GREAT THINGs !

I was disappointed: I only worked 5 stations in 2 hours with my 20 watts of SSB before the batteries ran out and I started shivering in the cold wind.  I learned a lot logistics-wise, such as don't do it in November, and sand gets everywhere!

But I really did expect the antenna to perform better than it did.  This was my first portable op using the vertical, and I think my inverted-V dipole used in the past seemed to perform better.

What are your experiences?

Jonathan, M5AEO




WHAT BAND? 

73
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K2DC
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« Reply #5 on: November 26, 2011, 11:46:10 AM »

Jonathan,

   Look up Dave, G4AKC.  I've worked him many times on 20M from the beach and the boardwalk in Blackpool, so much so that we know each other by voice let alone call sign.  I've worked him mobile, bycicle mobile and pedestrian mobile.  When the band is there he always has a cracking signal.  Maybe he can give you a tip or two.

73,

Don, K2DC
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N4KZ
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Posts: 598




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« Reply #6 on: November 26, 2011, 05:13:14 PM »

I have operated from beaches in Florida and South Carolina several times. And I have used dipoles and small verticals. While the verticals are convenient, their efficiency can be suspect while the dipoles played very well with good signal reports and lots of QSOs. If you're working 20 meters and higher, go with the dipole if possible.

73, N4KZ
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M5AEO
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Posts: 265




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« Reply #7 on: November 27, 2011, 11:49:11 AM »

Thank you all for taking the trouble to reply.

I actually made contacts spread across 10, 20 and 40 metres.  Two of the five QSOs were with Norway which kind of proved the sea-path theory; if you look at the map, the Norfolk coast and Norway have only sea between them.  Also RST reports were good both ways, so perhaps I just picked the wrong time of day!

I will try again with the dipole and report back.

M5AEO



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KD0NFY
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Posts: 75




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« Reply #8 on: November 27, 2011, 09:41:00 PM »

I did that this summer from the beach at Gulf Shores Alabama with a 28' vertical and a few 40' radials.  I was using an FT-817.  If I remember right my longest contact with the vertical was Canada. 

I did better with a 75' wire about 7' off the ground and a 30' counterpoise.  I used an MFJ 901B for a tuner.  Longest contact was Costa Rica.  This was all SSB with 5 watts. 

I called a lot of stations that didn't hear me, and called CQ over and over again without a response but I knew that going in.  Minus the fiberglass pole that was under 4' collapsed, the whole station fit in a messenger bag about the size of a briefcase.  I took a 12 amp hour gel cell for power. 
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VA7CPC
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Posts: 2383




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« Reply #9 on: November 28, 2011, 02:30:53 AM »

My best results were with a 20m vertical dipole, taped to a 31' fiberglass pole.  The top 2' just waves in the air.

Mounted near salt water, it works well, and avoids some of the ground losses of "vertical + radial" setups.

             Charles
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G8JNJ
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Posts: 492


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« Reply #10 on: November 28, 2011, 03:35:45 AM »

Hi,

I recently had my first experience of working 10m DX from the waters edge. It was quite an eye opener.

Using a 30W PRC320 manpack with attached 2.5m vertical and four counterpoise wires. I found that sitting on rocks surrounded by sea water gave about 10dB improvement vs. sitting about 50m away from the waters edge.

Regards,

Martin - G8JNJ

www.g8jnj.webs.com
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G0GQK
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Posts: 634




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« Reply #11 on: November 28, 2011, 12:45:20 PM »

There is a page about operating DX from an island somewhere on the net and the writer found the same as yourself. After trying different things they found that you should not lay the radials on the sand, they should be above the sand. As an example I feed a vertical similar to yours four feet above earth and the raised radials are tuned to length and have no difficulty in making contacts

Mel G0GQK
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