Hello,
I am hoping to make it to the Faroe islands this summer, and I plan to do some activations. Since the QTH is currently Arizona, it would be fun to be able to reach my “home association” W7A. I will use either a G90 or an FT-817, so 20w max.
My normal antennas are dipoles or end fed, but I was contemplating building an antenna with directional gain.
Doing a quick mockup on the SOTA-antennas designer, using the mast I currently use:
10m dipole with centre at 5m should have a maximum gain of 6.5dB at 28 degrees, 3dB at 14 degrees.
10m moxon at 3m has a lot of directional gain and rejection, peaking at 8.8dB but with a takeoff angle of 42 degrees, only 3.7dB at 14 degrees.
A delta loop at 5m (top) fed near the lower corner should have 3.4dB gain at 14 degrees, with the flattest takeoff angle, but no front to back rejection.
From this quick look at antenna simulation, it looks like the weight of a 2 element beam may not be worth building, since its main advantage would be front to back ratio for receive. My interpretation of the charts suggest that a Delta is probably more useful, though harder to rotate. At roughly 0 to 0.7dB advantage over a dipole, the Delta may also not be worth building.
I used a 10m Delta loop with apex at about 5m the other week. It seemed to work much better than my EFHW does as an inverted L on 10m. Not statistically valid as it’s only been used a few times. It also seemed a very quiet antenna. This was 58.9 degs North so not as far North as you will be but I worked 2 stations in AZ.
Tobias, Simon @GM4JXP has had great results with delta loops and moxons. Pictures in his latest report. I’m sure the moxon is a MM0OPX design
(youtube). I use a 15m delta loop to the same design as Simon uses and it works well.
Tobias, I could reach Arizona in the last few weeks several times with a J-pole hung from a 10m mast. TRCV was a KX2 with 10W in CW. If the sun spots play along all of your suggested antennas will work. I would opt for the delta loop. It seems to be a good compromise between gain, antenna complexity and ease of set-up.
I like the J-pole because it can be coiled up like a piece of cable. It can be set up quickly. Would be nice if somebody could calculate what the elevation of maximum gain for this set-up is.
Hi Tobias,
You seem to have decided on 10 metres as your band of choice - as long as the current conditions continue into summer, 10m should be viable from the Faroe Islands down into W7. Of the antennas you have considered, my recommendation would be the Moxon antenna if you can also carry a suitable mast to mount it on. I would suggest getting the Moxon up to 5 metres AGL if you can, not just 3m. Just in case the conditions aren’t so good, however, I would also take along a linked or off-centre-fed dipole as a backup to get you onto 15 and 20m.
I don’t know the Xiegu G90 but it appears to have an internal ATU which would give you more flexibility on the choice of antenna than a ‘naked’ FT818 (and the extra power can be useful).
In recent months I’ve routinely worked west coast US stations (including AZ) on 10m from the UK using 10W CW [from my KX2] with an non-resonant omnidirectional antenna (Cha MPAS Lite vertical) as well as with a 40/20/10 EFHW inv-L [not aligned in any particular direction].
If I were you, I wouldn’t bother trying to make your antenna more unidirectional as 1) you probably won’t need to [but I’ll leave it to the propagation buffs to say if 10m conditions will worsen from now until the summer] and 2) there are some keen EU 10m chasers (e.g. in Greece) that would like to work you.
My takeout of these is
-On TX, his dipole is better at all angles
-On RX the SCV would give you a lot of rejection of locals stations where the signal is coming down.(NVIS).
Which seems a tad unlikely on the Faeroes (and on 10m anywhere probably. Is NVIS a thing on 10m?)
Hello Tobias, I have operated several years from a small Fijian surfing island, several acres, in the Pacific as 3D2IZ. I always have used verticals. Simple and easily set up. Of course I would add a 4 or 6 wire ground plane. Also used resonant wires flown from a kite. I I made thousands of contacts throughout the planet. A vertical over a salt water surface, like the Faroe islands will make for a very efficient antenna, and with no man made noise sources to interfere you will find your results to be remarkable. I have had a similar experience operating /MM on voyages to/from Hawaii from W6 land. I used resonant verticals (1/4 wave or 3/4 wave) strung from palm trees or attached to fiberglass telescoping “fishing” pole (not carbon fiber - they conduct). Ground planes were also resonant 1/4 wave elements, typically 4 wires. I would also suggest you refer to some of the literature from DX-peditions as guidance. Those teams have it all dialed in for ease of assembly and getting results. Lastly, I found computer logging was mandatory - the pile ups were enormous and would last for hours. I could only take so much, and would have to beg off to find time to sleep and surf.
Given the magnificent peaks and sheer drops of the Faroes a vertical with 4 elevated, tuned radials would be a good choice. We use them here in W7W for field day and they work great on peaks and ridge-tops. I would also say that having one for 15m might be a useful tool as well, the number of days I hear EU on a modest setup here in W7W are about 3x more on 15m than 10m.
The moxon would be a good choice as well – the modeled takeoff angle will drop quite a bit if you’re operating from a significant hilltop. The benefit to the directional antenna will likely be the rejection of signals from the backside, which will help attenuate the EU wall and help you to hear the West Coast over more local callers.
You can make a Moxon vertical, and the dimensions work out pretty favorable to do this at 10m on a SOTA pole.
You can end feed the moxon at the bottom.
The end wires don’t have to be dead square, they can be angled, which helps making a vertical wire moxon on a flimsy pole.
Another simple idea is just use a vertical EFHW it’ll only be 5m, maybe 4m with an end loading coil. Then a second one ~1/4wave away will work as a reflector. If you have an offsider, they can walk around with the reflector, making for a simple rotator. You could put a string between them the right length, just above the guys.
The unique advantage of a moxon over other directional antennas is that can have about the deepest null at the back of any simple antenna. The spacing between the tips of the moxon is what tunes the depth of the null. (i.e. the length of the driven element tips tunes the resonant frequency, then the length of the reflector tips can tune the depth of the null)
If it’s a howling gale, this is the one that will actually work. Still, doesn’t seem terribly likely on a hilltop in the Faroes.
A half-square is a solid performer as well, and worth considering as another simple option. A 20m EFHW can simply be set up as a10m half square if you have two supports. Measure and mark the corner locations ahead of time. And for 10m, you don’t need very tall poles.
As you can see after lunch 20m band gives you highest chance of success to reach Phoenix.
Off course such simulation should be done day or two before activation to give you more accurate picture.
VOCAP also calculates most likely take off angle, and that is 10-15deg on 20m band.
Based on that data I would choose EFHW4010 (66ft wire) setup as a half square which gives low take off angle on 20m band without need for high mast.
As it happens 20m is also best band for European QSOs, with 15 and 17 for southern Europe.
Off course if 10m is open than the entire World is available. In such case I would put up single band vertical EFHW10 (15ft wire) as high as you can get it.
Hi Marek,
I think Tobias wants to take part in the 10 metre SOTA challenge - hence his choice of 10 metres as the primary band, I agree with you however that 20m may be suited better for that path (hence the reason I suggested at least taking a dipole along for 20 & 15m).
In midsummer there is a reasonable chance of multi-hop Es but it still won’t suffice to get to Arizona from OY on 10m. F2 will do the job if the SFI is high enough. Earlier in the year when the SFI was up to around 190 I was finding west coast USA activations easy to hear but the last couple of days the SFI has been down to below 130 and 10m has been very disappointing, it all depends on the sun - or more accurately, since solar activity is asymmetrical in longitude, which part of the sun will be facing you when you are on OY.
So here is an interesting and very simple proposition. Short EFHW2010 ie. 10mtr wire as inv-L. End of the antenna pointing SW (7 or 7:30 on the clock) on a short 6mtr mast. Transformer 1-1.5mtr from the ground.
2.3dBi at 10deg and 4.84dBi at 22deg. Again low angle of radiation is needed for Arizona or West Coast of US.
It will gives option of 20 and 10 to reach Arizona and most of Europe.
Now a crazy part, place 5.2mtr reflector 2mtr to the right/left of vertical part of the antenna and you gain about 2 dBi. ATU might be needed to adjust for SWR. This reflector works only on 10m band so it would need to be put down for 20m band operation.
Good choice - it’s worked for me on 10m. But I question the orientation. Assuming that your simulation has the radio path following the Great Circle route (from Faroe Isles over Iceland to Arizona) wouldn’t the best bearing for a directional antenna be more like WNW than SW.
The discussion about providing a highly unidirectional antenna makes interesting reading but I assume that Tobias @KK7BCO wants to work AZ but not only AZ but other Dx locations.
There’s been nothing said about the topology of the summit(s) to be activated or the weather.
You will most likely walk in rain, in sunbeam from multi-coloured skies and in rolling fog. The average temperature in July is 11.5 °C (53. °F).
Being close to the common cyclone tracks in the North Atlantic region the islands have a windy climate. The mean wind speed is generally high in the Faroe Islands.
So, if it were me going to a previously unknown summit in cool, wet and very windy conditions, I would take a simplequick-to-deployrobustmulti-band antenna with a small footprint, i.e. a vertical with 4 short counterpoise wires (plus a rubber mallet for the ground spike, in case the summit is thin soil over rock).
I never thought or said it would. I mentioned SpE ranges in relation to working shorter contacts in to Europe to give more local coverage as well as what can be done via F2.
Having used my loop only a few times, it impressed me by how quiet it was. On one occasion I worked plenty of local-ish EU stations in HB9/DL etc. The last time it was YO,SV (much further away) and zillions of US stations. Talking to local club member he pointed out loops work well when low down compared to other antennas. His 40m loop (arranged and fed like mine) is in the trees in his garden with the base about 2m AGL. He has no difficulty working VK/ZL etc. from GM on 40m with 100W. You would need a good vertical or a dipole mounted much higher to do the same.
If you consider how much crud you may have to take with you to play radio then that may affect your choices. If you have a 10m loop it will work on a 5m mast. Likewise a 10m and a 12m 1/4wave GP fit easily on a 5m mast. Such masts are generally light and the travel fishing rods collapse to less than 60cm so fit into suitcases with ease. My loop, 10/12m 1/4waves, a 5m travel, the guying kit and the few short runs of coax needed for them weighs under 1kg. The suggestion of a 15m 1/4wave is one I’d consider seriously. You can squeeze one on a 5m pole but TBH, they really need 6-7m poles.
You don’t say if you can operate CW. If you can, the 5W 817 is not a limit. And… depending when in the Summer you are in OY, a 6m flowerpot could be useful. Lots of people would be pleased to work OY on 6m not just SOTA chasers!
It’s difficult to really know were to draw the line. For example I’m away on vacation with the family in the UK in a few weeks. Space is a premium so I’ll have the tiny SOTA gear, 20m QCX, 30m (and 40m reduced performance) QCX, 20/30/40m EFHW. That will let me do a few activations and work UK and EU with ease, maybe some DX. Later in the year we have a family vacation in a less frequently activated island which is classed as Africa. Whilst I’ll be flying, there’ll be more space so the KX2 and the 10m loop will be in the bag as well as other antennas.
SFI is 125 today and DL’s are working HL and 4S7, I’s working VU and there’s some nice propagation from F to TY5 (Benin). The spot says the TY5 is calling and calling and nobody is going back!
