HF shore station

[wad'nwind]

Originally Posted by NoTies

I want to set up a shore based HF station so I can do my cruising vicariously for a while. I'm familier with boat installs but no experience with land based. I have a iCom IC-M710 and automatic tuner. What do I do for antenna and/or ground plane? I need to have the set-up designed before I can apply for a station licence.

Dear Pete,

I have good results using a skywire-loop or cloudburner with a autotuner like AT141.
Advantage is that you do not need any particular groundplane. Because the loop is closed, it has a very low man-made noise sensitivity.
At the lower bands the radiation lob's are pretty steap, but on higer bands the lob's are more horizontal.
Lots of info at google

If you want to stay friends with your neigbours, do never use a monopole antenna with couterpoise, because of LFI at (chinese) audio and computer equipment

[El Pinguino]

By the sound of things vertical near the middle would be best.... appears to be workable... all the roof sheets need to be bonded... ... will ask around in the morning.

It may be worth asking the sailmail people .... they run shore side stations on all the maritime frequencies... I think the earliest one on the west coast of the US worked out of a West Marine store.

[NoTies]

Thanks Mr Peguin. The whole building is steel framed so full continuity. I'll await your response oncce you have spoken to your gurus.

[btrayfors]

Pete,

You have the setup required for a very simple and effective antenna system, with the M710 and AT130 or AT140.

Antenna: Just run a length of insulated wire -- any size, but AWG 12 or larger is better for physical strength -- as high and as long as you can from the antenna tuner lug;

Ground plane: you've got it....use the steel roof, run a heavy wire or wide copper strap from the roof to the antenna tuner ground lug. The tuner should be located as close as possible to the roof, so that the wire or strap connection is short.

You'll need a length of coax...RG8X or RG213 if available...from the transceiver to the antenna tuner. This can be any desired length.

Be very careful with the terminations, i.e., the connectors to the radio and to the tuner. Be sure there are no shorts or opens.

That's it. No need to make it more complicated.

Bill
WA6CCA

[hellosailor]

Pete-
I would also recommend the ARRL Antenna Book, and I think that normally comes with a CD copy of the book so if shipping is too costly, maybe someone can just forward the CD to you. Or perhaps the ARRL would simply sell you a CD, especially if the station is also to be used for SAR purposes.


Using the metal roof of a 100' shop as a ground plane, probably is a good idea, IF there are decent connections between the panels. At radio frequency, they're probably good enough and better than having to spread multiple radials. If for some reason the roof wasn't working, you could spread radials on top of it and just "tar" over them, so nothing lost in trying.


As to the antenna itself...there are advantages to a vertical (omnidirectional) and disadvantages (guy wires, or a tower, both vulnerable to high winds) and if you look online many companies make fine multi-band verticals that can be erected easily.


With a horizontal, you can always build one from wire, inexpensive and again documented many places on the web. The problem there is the will always be directional to some extent. But they're cheap enough, so you can put one up, and then switch to a factory-made vertical or re-orient the horizontal one and it sounds like the only major speedbump might be getting licensing(?) permission to move the antenna.


Don't skimp on your cable, and do make sure your cable run is done properly, because the cable is very much as important as the antenna. Again, the ARRL is a great resource because "HF is HF is HF" whether it is ham or marine. Plenty of ham-oriented web sites about the whole system as well.

[NoTies]

Thanks for the info everyone. I'll try using the shop roof as a ground plane and initially try a horizontal antenna as the main communications I will be using are north and south (the direction Vanuatu archipelago lies) and the shop lies east/west. Licencing is not a problem, all government departments want here is your money.

[El Pinguino]

Have just consulted my gurus....

Some suggestions.....

Long wire ( 40 footish ) to a coconut palm.... get a few star pickets ...grind of or otherwise get rid of the bitumus (sp) coating.... drive into ground as close as pos to tuner and use them as your ground plane. (AKX has set up lots of rough and ready stations in PNG and Tuvalu over the years...as I write this he working portable from a roadside somewhere in Tasmania with a squidpole)

Use the roof as your ground plane... run a 'sloper ' across the roof to a palm beyond the far end.

Find a 'moonraker' vertical ( one of the tasmanian ones) on one of the wrecked yachts... set that up above the roof using the roof as a ground plane. I have a moonraker ( about 5 metres) on my boat - amonst other stuff - hooked up to an Icom7600 and an AT-130/40...works good. Doesnt need staying.
As long as it is insulated from the roof etc at the base you could just use a bit ( 5 metres or so ) of alloy pipe as a vertical.
Hope this helps....
Cheers,
Ping

[NoTies]

Thanks Ping, I'll give the second option a try this weekend and see how we fare. The roof survived 150 knots so should be well fastened. Unfortunately, most of the moonrakers were destroyed during the cyclone, I've had to airfreight more in for clients.

[El Pinguino]

Originally Posted by NoTies

I mainly want 8 megs to run the local cruiser's net but also want a greater range for possible use as SAR station so anything from 2 megs up I guess.

If you can get it up into the air a dipole cut for your 8 MHz frequency would be a very good option for yachts not too far distant...

[ka4wja]

Pete,
First some brief info...

1) You're going to want to use a horizontally polarized antenna, NO higher than 30' - 35' above ground for your 8mhz comms....
2) For comms below that freq, you could benefit from a horizontal antenna higher up, but getting one much higher than 50' - 60' is usually difficult, so no worries there...
3) Since you already have the remote tuner, it makes sense to use it!!
And, while I agree with Bill that a piece of wire from the tuner strung up will be a good inexpensive antenna, there are some better/more versatile/higher efficiency choices...
a) run a loop of wire 100' - 300' around, in any reasonable shape, square, rectangle, triangle, etc. supported about 30' - 40' above ground (or above your shop), with one end to the tuner's output lug and the other end to the tuner's ground lug....
The tuner will tune this antenna very easily on any freq where the wire is .75 wavelengths or more in length (loop circumference)....this can be a rather large loop for coverage down to 2mhz, but it is a wonderful antenna for both daytime and nighttime Near Vertical Incidence Skywave comms (2mhz - 9mhz, from 20miles to 500 miles), and can be a very good antenna for nighttime long-range comms on 4mhz - 8mhz as well....

Originally Posted by NoTies

I want to set up a shore based HF station so I can do my cruising vicariously for a while. I'm familier with boat installs but no experience with land based. I have a iCom IC-M710 and automatic tuner. What do I do for antenna and/or ground plane? I need to have the set-up designed before I can apply for a station licence.

Originally Posted by NoTies

I mainly want 8 megs to run the local cruiser's net but also want a greater range for possible use as SAR station so anything from 2 megs up I guess.

Originally Posted by NoTies

Thanks for the info everyone. I'll try using the shop roof as a ground plane and initially try a horizontal antenna as the main communications I will be using are north and south (the direction Vanuatu archipelago lies) and the shop lies east/west. Licencing is not a problem, all government departments want here is your money.

Understand that horizontally polarized antennas have a significant advantage over verticals (6+ db, even compared to verticals over sea water, until you look at VERY low radiation angles of < 3-5 degrees, where the vertical shines)
And, when compared to ground-mounted verticals with poor ground systems (which MOST are!), almost any horz antenna will beat it by 10+ db!!
So, unless you need long-range comms (> 3000 miles) on 2mhz - 4mhz, stay with the horz antennas!!


There's a LOT more info/advice I could give, but just wanted to give you a few brief tips first...
And, I can add more later, if you desire...
(FYI, I teach radiowave propagation, antenna design / engineering, etc....so your question is right in the middle of my forte...)


I hope this helps!!

Fair winds..

John

[ka4wja]

Pete,
I wrote in a rather matter-of-fact way, above...
http://www.cruisersforum.com/forums/f13/hf-shore-station-145350-2.html#post1816068
Unfortunately that can put some off, so here is some info in a bit more concise way...

Originally Posted by NoTies

I want to set up a shore based HF station so I can do my cruising vicariously for a while. I'm familier with boat installs but no experience with land based. I have a iCom IC-M710 and automatic tuner. What do I do for antenna and/or ground plane? I need to have the set-up designed before I can apply for a station licence.

Originally Posted by NoTies

I mainly want 8 megs to run the local cruiser's net but also want a greater range for possible use as SAR station so anything from 2 megs up I guess.

Originally Posted by NoTies

We have a workshop about 100' long that it can be mounted on the roof of. Budget not too much of an issue,

Originally Posted by NoTies

OK, the roof of my shop is roughly 3000 square feet, made of steel, as is the whole building. Can I use the roof as the ground and rig a single wire antenna up to 100' long above it?

Originally Posted by NoTies

So, vertical on top of the roof? I can do a vertical beside the roof if needed. 2 megs is not a game breaker, more a nice to have.

Originally Posted by NoTies

Thanks for the info everyone. I'll try using the shop roof as a ground plane and initially try a horizontal antenna as the main communications I will be using are north and south (the direction Vanuatu archipelago lies) and the shop lies east/west. Licencing is not a problem, all government departments want here is your money.

Using what you wrote here in these posts, I'll summarize:
1) You wish to communicate throughout the Vanuatu archipelago, in a North-South orientation, using the marine bands from 2mhz thru 8mhz (2mhz isn't a necessity, and 8mhz is an absolute)...
2) You have a shop with a 3000 sq ft metal roof,about 100' long (E-W) and about 30' wide (N-S)....(not sure how high this roof is, but I'll assume a single-story structure w/ a flat or slightly-sloped roof, of about 8' - 12' high...)
3) Licensing is not a problem, and budget/cost is not too much of a problem either (nice!)...



Antenna ideas::

Knowing all of the above, there are a few things that pop out immediately...and they are:
a) You can use your AT-130 tuner, as the feed-point of a large horizontal loop antenna...
Make a loop of wire, about 250' around (200' min, 300' max), supported from masts/poles at the corners of your shop, keeping the loop about 30' - 35' above the ground...

This will give you one single antenna that your AT-130 will tune from 2mhz thru 25mhz, and give you very good performance on 4mhz, 6mhz, and 8mhz, for local/regional NVIS communications (both day and night), from 0 to 300 - 500 miles away.....
And, adequate performance on 2mhz...
And decent daytime/evening long-range comms on 12mhz, 16mhz, etc. out 1000's of miles...(but some odd patterns can make higher freq comms less effective)...
As well as nighttime long-range communications on the 4mhz, 6mhz, and 8mhz bands....out more than 2000 miles or more...


b) Without using the AT-130 tuner, or allowing you to use the AT-130 tuner for another antenna....
Build and install 3 dipoles / "V" antennas, coaxially fed from one common feed-point (known as a "fan-dipole" antenna), for 4mhz, 6mhz, and 8mhz....(using 4.125mhz, 6.215mhz, and 8.291mhz, as the design freqs....but these will allow coverage on other channels/frequencies on these bands, including cruising nets, etc...)

This would be 3 simple wire dipoles, commonly fed, in the center (I'd recommend a good current balun at the feed point), supported by a few poles/masts at the edges of your shop....use double-braided Dacron/polyester line as support ropes/lines....(actually if you rig a block at the top of the support poles/masts, it will make installing/rigging/adjusting the antennas VERY easy!!)

Please cut the wires a bit longer, and prune to resonance as needed.....these dimensions will vary!!!

--- The 4mhz dipole = 113' 5" long overall...supported from masts/poles in opposite corners of your shop (giving you about 104' 5" corner-to-corner), about 45' - 55' high above ground at the ends (typically a 40' - 50' pole will work fine here), and allow the wire to droop down in the middle (feed-point) to a point about 25' - 30' above ground, where you balun/feed-point will be (and where the 6mhz and 8mhz dipoles will also be attached)...

--- The 6mhz dipole = 75' 4" long overall....supported from some other masts/poles in opposite corners, or at the ends, of your shop...at about 33' - 38' high above ground, and allow the middle to droop down a bit to the feed-point at about 25' - 30' high above ground....

--- The 8mhz dipole = 56' 5" long overall....supported from the masts/poles in opposite corners that are supporting the 4mhz antenna, (or other poles/masts if you desire at the ends of your shop, etc.)...at about 25' - 28' high above ground, and either run flat across, or allow the middle to be pulled up slightly to the feed-point at about 25' - 30' high above ground....

These 3 dipoles share ONE common feed-point (preferably a hi-quality 1:1 current balun, such as DX Engineering, or Balun Designs, etc....or even Radioworks), and operate as ONE antenna.....and from this feed-point/balun you have ONE coaxial cable (RG-213 or RG-8x) run down from the center of these antennas (keeping the coax running down away from the antennas for as long as possible and then into the building and to the radio...

So, this one antenna, just like the big horizontal loop antenna above in "a", will give you excellent coverage across the Vanuatu archipelago, day and night, and require NO remote antenna tuner at all...


Which one to choose???
Well, antenna "a" is simple, fool-proof, and works well....but antenna "b" can be optimized for your exact application and can be a slightly better performer (although the difference will be hard to measure in the real world)...
Since you mentioned having access to much rigging / masts, etc. if you didn't already have the AT-130, I'd recommend antenna "b"....
But, since you DO have the AT-130 already, and also desire comms on other frequencies, then antenna "a" is my best recommendation....


BTW, you'll notice I didn't mention much about the "metal roof".....yes, this will improve you antenna performance, especially the 8mhz performance of antenna "b", the improvement will be small but noticeable...
But, be aware that metal roofs CAN be a pain for RECEIVING signals, as their movements and constant making and breaking of electrical connections CAN cause receive RFI....this is usually not an issue with antennas aways away (such as dipoles, loops, etc.) and in areas where there is little other RF sources around...
But, if using a vertical antenna mounted on the roof, and/or using the roof as part of your antenna's ground / counterpoise, metal roofs are many times problematic!!

Originally Posted by El Pinguino

appears to be workable... all the roof sheets need to be bonded...

As El Ping wrote, they NEED to be bonded and completely congruously connected throughout, in order to even be considered as part of a vertical antenna system...



Speaking of "vertical antennas", as I wrote earlier, this is BIG mistake for you and your application, when compared to even a simple big loop of wire strung up and fed with the AT-130 tuner (one end of the loop to the "antenna output" terminal and the other end to the "ground" terminal), a vertical antenna is going to be a significantly worse antenna....MUCH worse!!!
Even if mounted in the center of your large metal roof, and all the roofing panels are completely connected together, and even if your shop is overlooking the ocean (just yards away), and you had very good soil conductivity (which you do not have), even then the vertical's "gain" at high radiation angles (which are needed to communicate from beyond line-of-sight out to 400/500 miles) is a NEGATIVE number, of -8dbi to -20dbi (depending on the exact angle and both near and far field ground conductivity)...
Versus a simple loop having +6 to +7.5 dbi gain from about 50-60 degrees to 90 degrees (straight up)...it is these highest angles of 60-70* up to 90* that allow daytime regional communications on 2mhz thru 8mhz...
(and if your shop is inland, or on sandy/rocky soil, or you don't have LOTS of radials in addition to the large metal roof, the "gain" of the vertical is even worse!!)

What this means in the real world, communicating with vessels from 20 miles out-to 300 miles away, day or night, on 4mhz, 6mhz, and 8mhz, is that the vertical antenna WILL be at least 15db to 25db worse than the horizontal antenna....at ranges of 400 - 500 miles, day or night, the vertical is now only 10db - 15db worse than the horizontal antenna....
{FYI, a 10db - 15 db difference is like multiplying your transmitter power (and the other stations'/vessels') by 10 - 30 times!!! Yes, than means using a big horizontal loop compared to using a simple vertical, is like using the vertical with a 1500 watt to 4000 watt transmitter!!!
(I know that laypersons will question this, but it IS fact...)
Just wanted to be clear as to how important antenna choice is...}

Nighttime long ranges, beyond 1000-1500 miles out-to 5000 miles, the vertical will be better than the low-mounted horizontal antenna, as the vertical (depending on ground system and soil conductivity) will have a "gain" of -5dbi to +1dbi (at angles of 10-15 degrees) and the low-mounted horizontal dipole will have "gain" of -5dbi to -2dbi (at angles of 10 - 15 degrees), but here the differences aren't as large....(and of course if you raise the horizontal dipole up to a height of only 1/2-wavelength, it will have a "gain" of + 1dbi to + 3dbi (at 10-15 degrees) and if raise it up higher the simple dipole's gain goes up to +4dbi to +6dbi....
(sorry for the rambling....just wanted to be clear as to WHY a vertical antenna on-shore, is a BAD idea for your application!!!)
I've posted antenna patterns before, and will do so again if you desire....please advise...


I do hope the above helps, without getting you overwhelmed..

Fair winds..

John