Kite-lifted long wire antenna operation (Part 1)

[G8CPZ]

Reading previous threads on using a kite to lift a long wire (LW) antenna I get the impression that the wind speed and direction usually changes too much at SOTA summits to be practical and is very time-consuming compared to using traditional pole-erected antennas. Please tell us if your experience is otherwise.

I want to experiment in a non SOTA situation (hence OFF TOPIC posting) with a kite to lift a LW and am looking for advice especially regarding change of wind direction. I’m concerned the antenna will move around and I don’t want to operate “Pedestrian Mobile” trying to follow it.

I foresee a problem if the wind direction changes. Without changing the kite-cord tether point (to compensate), the top end of the antenna will try to follow the kite. As I intend to tether the antenna at the bottom it will no longer be vertical (which is not a problem radio-wise) but it would be under greater tension to stretch.

BACKGROUND
I’ll be using the method described by Richard, G3CWI, in his on-line article, i.e. you attach 5m of shock cord to the top of the LW (e.g. 50m of thin wire for 5/8th wave on 80m) and they hang vertically from a knot in the kite cord which is about 10-12m down from the kite. The bottom end of the LW is tethered to a metal screw-in ground stake (and loosely connected to a 9:1 UnUn then coax feeder and radio).

So we have a right-angled triangle: the vertical LW/shock cord (“opposite”), the kite cord (“hypotenuse”) at roughly 40(?) degrees to the ground (but I assume this will vary depending on weight of LW, lift from kite in particular wind speed, other factors?), and the horizontal distance along the ground (“adjacent”) between the kite-cord tether ground stake and the antenna tether ground stake.

With me so far? Or have you got bored?

Doing the trigonometry, the kite cord (from ground tether to top of shock cord) is about 86m. Plus the 10-12m up to the kite gives a total cord length of 100m. Distance on the ground between ground stake tethers is about 67m.

Now here’s the tricky bit. We don’t get to decide the wind direction. If you wanted to fly with any wind direction AND you want to sit in a particular spot, you would need to have the vertical LW in the middle of a circle (where you are) with radius 67m (as viewed from above).

However, the bit of land where I want to try this overlooks the sea. In calm weather (winds 6-12mph), I think there should be onshore breezes during the day. [In theory: land is warmer than the sea during the day/summer/autumn so cooler higher pressure over sea causes air to move to warmer lower pressure over the land]

If true, I should be able to tether the kite cord at the ‘sea end’ of the field and the kite should fly inland (and over the bench where I want to sit on!)

Faulty logic?
Things overlooked?

Anyway, your comments please.

[G1INK]

There’s a video by M0XMX on YouTube about kite lifted antennae. Easy to find on his YouTube channel. You may get some pointers there

[G8CPZ]

@G1INK

There’s a video by M0XMX on YouTube about kite lifted antennae

Thanks. I watched the one where M0XMX lost his kite into the sea because the cord knot wasn’t secure. Important lesson to be learnt. I’ve also watched other kite-antenna videos on YouTube. Unfortunately, I could find none that address my question.

[G1INK]

I know Mike 2e0yyy tried a kite (think he lost it in the Peak District).

[G4POP]

I have run the aerial wire as a slopper with the wire running down alongside the kite cord and diverging about 20ft from the kite anchor point to an earth stake with my static bleed resistor and tie off chord.

I always use a short length of lower breaking strain chord between the kite and main kite chord then if there is a sudden unexpected gust that could break the main cord the ‘Fuse’ cord breaks first and the unstable kite will eventually land but my aerial and all else is safe.

Retrieving the kite after an operation can be tiresome if you dont use a Carrabin clip with a strap attached to ‘walk’ the kite down from anchor point to kite, then once the kite is tamed it is easy to wind the aerial wire and kite cord up because are no longer under preasure.

Happy kiting de G4POP

[VK3ZPF]

I’ve never done kite activation so I am interested in how you get on.

Bernard @VK2IB has a blog post about SOTA kite activation

Mt Hotham VK3/VE-006

Cheers
Peter

[DL1CR]

A few years ago I had very successful kite activities. My usual 20m long End Fed was tied to the kite string about 10m below the kite. This allows the kite to ascend easily and pull the antenna up.
The efficiency of the antenna was enormous and my “CQ kite” gave me tremendous pile ups without spotting.
The difficulty was that you needed 2 operators, one on the trx and one on the kite. That’s why it did not work for a long time.
Short video on this DL1CR DL3HC Kite portable - YouTube
73 Chris

[VE1PVH]

I’ve done quite a bit of flying antenna’s over the last couple of years. I have never used them for SOTA activation yet though. I’ve flown dipoles, end feds, OCF’s, inverted Vee and verticals all to varying degrees of success. If there is one thing learned it’s the more complicated you make the support system, the more of a mess your going to have if it doesn’t work. I now fly a simple end fed anchored at the same point as the kite cord. I leave slack in the antenna so it doesn’t wrap around the kite cord. I use a 6’X4.5’ sled kite. Flying antenna’s is a lot of fun! The wind shares the same opinion.

[VK2IB]

A kite is a great way to provide a “sky hook” that can support an antenna. Based on my experience I’d offer the following suggestions.

1. Pick your kite carefully. Use a “sled” type. These are designed for lifting and are stable in flight, as long as the wind speed doesn’t fluctuate too wildly. Pick one that’s big enough to carry the weight of your antenna plus the effects of wind dragging on the wire, but not so big that it pulls your arms out of their sockets or needs a pilot with the physique of a sumo wrestler.

2. Plan your rigging thoroughly, then test it before you want to do your activation. I’d suggest getting the kite up first, check that it’s doing what you expect and that you can control it, then bring it back down before you attach your antenna to it. Don’t attempt to bring the kite down by reeling in the flying line. Clip a carabiner on the line and walk it down.

3. Persuade someone to assist as a kite pilot who can keep an eye on it and make any adjustments that may be needed. You’ll probably find it hard to both operate the radio and fly the kite.

4. I don’t need to lecture you on safety, do I. Overhead power and telephone lines, trees, nearby houses, airports… You need a lot of clear area for this. And don’t forget a static bleed resistor. It’s amazing how much charge will build up on the wire if you don’t do this. It probably won’t kill you but it’ll give you a jolt, and it might be fatal for your radio’s front end.

In a seaside environment, the sea breeze will probably die away shortly after sunset. Anyway, you probably want to get the thing down in daylight so you can see what you’re doing when you go to pack it all up.

Good luck!

73

Bernard VK2IB

[RX9WT]

I want to share my experience in using a kite as a lift for an antenna. Earlier, traveling on the RDA (Russian Districts Award) program, I tested different versions of DX antennas on 160 and 80 meters. GP type antennas had good results. But tall masts can only be lifted with helpers. One does not work in any way.

Experimenting with various types of kites and tuners for several seasons, settled on a soft kite - a paraglider. Of course, the automatic tuner is ideal in this situation, since such antenna parameters are never stable. The tuner AT-130 solved all the problems.

The kit turned out to be very compact and convenient for installation by one person. The flying force of the kite is enough in excess for a wire antenna longer than 100 meters. when the wind is even, the antenna becomes almost vertical. With a gusty wind, the position of the antenna, of course, is not so stable. But the efficiency does not change very noticeably.

Choosing the length of the wire, I settled on the size of 5/8 lambda. This length allows to have sufficient efficiency and does not require a large number of radials. Only 2-4 was enough, about 0.1 lambda long. Of course, such an antenna is relevant only in windy and clear weather. There was a case, in October, bad weather, a kite hid in low clouds. I managed to make only a few QSOs - the antenna and the kite fell on the field. A layer of ice on the surface of the kite and antenna wire made the system unsuitable for continued flight.
In calm weather, instead of a kite, it is convenient to use a balloon filled with helium.

Of course, in this case the wire must be taken thinner, since the lifting force of a balloon with a diameter of about 1 meter is small.
It’s probably not advisable to lift the AT-130 tuner to the summit in a backpack. It is designed for slightly different conditions. But the idea itself is quite viable, it seems to me. A compact and economical tuner for QRP kite antenna can be bought (for example LDG-817) or assembled by yourself.
I want to add that in the summer it is difficult to use such high-raised low-band antennas because of the strong QRN. Do not forget about the danger of lightning!
73!
Vlad RX9WT

[GM0HUU]

Thanks for topic. Some interesting advice and references in the replies. Kites and balloons are things I have wondered about for SOTA or /P operation. I have also wondered if anyone has tried using a drone to hoist an antenna?

[G8CPZ]

Question on anti-static bleeding method

Walking the dog in lovely late afternoon sunshine yesterday along the wide low-tide sands on the River Kent estuary near my village I felt inspired to resume my interest in kite-borne antenna radio using a vertical end-fed long wire [for 60m and 40m] suspended a few metres below my [SOTAbeams] kite from near the upper end of the flying cord. This is not intended for SOTA activations but just a bit fun and a challenge at my local coastline [somewhere with not many people around!]. I’ve tried it briefly a few times but have been nervous about connecting it to my precious KX2 for fear of electrostatic damage.

In the example setups I’ve seen they use a bleed resistor (about 1M-ohm) from the bottom of the vertical long wire to ground to bleed off static build-up in the antenna wire due to friction with the air.

I plan to use a 9:1 UnUn [redundant from an old antenna project] to help the KX2 internal ATU match the hi Z of the EF LW. The ‘hot’ terminal of “9” side connects to the end of the EF-LW and the ‘cold’ terminal goes via a short wire to a [‘dog lead’ type] metal ground stake that skewers about 15 cm into the ground. The ground stake also acts as a physical tether for the lower end of the antenna wire via a short length of bungee cord.

I think the “9” side of the UnUn will provide an adequate DC path to the ground stake to bleed off static (in lieu of a bleed resistor) and my KX2 should be isolated on the other side (“1” side") of the UnUn.

Do you think this is a safe alternative to the bleed resistor?

Regards,

Andy G8CPZ

[MM0FMF]

It’s a DC path inside the UnUn so yes.

[G8TMV]

@G8CPZ

Do you think this is a safe alternative to the bleed resistor?

As Andy says it’s a DC path so yes. However, I’d be worried about how good your DC ground is. The antenna will work with just the ground wire and the spike acting as a counterpoise even if it’s insulated from the actual ground but your “safety” ground needs to be a low DC resistance to earth which probably means at least a 3-foot spike.

[MM0FMF]

@G8TMV

I’d be worried about how good your DC ground is.

Yes. I’ve no experience of what is needed here. What earthing stakes etc. are other kite antenna users using?

[G4AZS]

Well, if it is normal to use a 1 Mohm bleed resistor, I suppose the ground connection needs to be of that order or less. Maybe stick in two pegs a metre or so appart and measure the resistance between them…?

[G8CPZ]

If a 3-foot ground spike is really necessary to get an adequate electrical ground connection, it would doom [for me] the temporary use of kite-borne antennas as impractical in most terrain in this area.

My back garden is typical of the area 10-15cm of soil over rock hard 340M year old Dalton Limestone. The sands at the estuary are more penetratable

As I understand it the current due to friction static is micro amps, hence the 100k - 1M ohm bleed resistor.

[K6HPX]

Hi all,
Had very good experiences using an end-fed, half wave vertical on 40M.
Used a para-foil; flies at a very high angle, and pulls like an ox.
Tether was to a very large public bench. This was long ago, before SOTA.
Was running 5 watts to an old Oak Hills rig. Lots of fun!
Think that a Zepp would be very good for this; possibly the best, although it is heavier.

Best, Ken

[BX2AI]

Thanks for this thread and some valuable advises. I am interesting in trying this “wire antenna hook” method. (not for SOTA activation though since I think there are rare summits which could be suitable to deploy a kite.)
Regards,
Huawei

[G8CPZ]

@G4AZS

Maybe stick in two pegs a metre or so apart and measure the resistance between them

Between two metal ground stakes 1m apart screwed ~15cm into slightly-damp sand on the beach I measured about 300-500Ω. Doing the same on my back garden lawn I got about 1200-1400Ω.

A ground plane of that resistance per metre radially about the ground stake should be more than adequate to bleed μA’s of static due to friction with the air. The 9:1 UnUn has a DC resistance on the “9” side of about 0.5Ω.

At the risk of stating the obvious, it would be highly inadvisable to operate a kite-borne antenna even with a hint of thunderstorm in the region and the electrical grounding is not intended for bleeding static in that circumstance. Fortunately, there are plenty of clear days to indulge in this occasional activity.

Yesterday I did a ‘test flight’ on the wide flat sands of my local estuary in what the Wx forecast called a “gentle breeze” (9mph). The SOTAbeam kite had no trouble lifting off even when carrying the 25m of UltraLite wire (my 5/8th 40m vertical EF) and bungee cord but didn’t gain enough height to get all of the wire off the ground except during gusting.

One trial is not statistically significant but it looks like the wind speed needs to be a bit higher for the kite to fly higher (as I’ve seen it do many times before) to support the weight of the antenna.

The problem I foresee is the kite and thus the antenna wire moving around as the wind direction changes a bit. On the next trial (with higher wind speed) I’ll tether the antenna wire near the bottom end via 1m of bungee cord to the ground stake. I might even take the radio.