I was wo dering if thete might be interest in builing arrow antenna clones or perhaps a slightly different (hopefully.improved!) design?
Thinking that it will be great to have the skookum rig at the OTC and would like.to have a setup for sat hunting when I am out on my own.
Anyone interested?
I love this idea. I was going to buy an Arrow but I’ll see if there’s interest in @Doug’s idea here first.
The Arrow costs about $200 and is super professional looking. I’m not sure we’ll do as well.
Even if we don’t build, at the very least we should perhaps look at a group buy of Arrow antennas.
I always enjoy building antennas. Happy to have one that’s maybe a little more robust than my measuring tape yagi.
I talked to @Doug about this last weekend. He has some cool ideas to make one that is significantly better than the Arrow. His will be much easier to store, for example. He needs a bit of time to sort out his ideas but I have personally put off buying an Arrow for awhile until we see if this project advances.
Adrian brought his Arrow in on the weekend. Looks good. He made a couple of satellite contacts right from that parking spot.
I should mention, the price since Adrian @VA7YEP-obi-wankenobi bought his has increased to about $300 CAD.
to reactivate this old thread…
With an Arrow you’re paying for the beautiful mechanical construction.
If you just want to play with satellites, basic yagis are simple to build. Here’s one of mine from 20 years ago, for 70 cm.
It’s a piece of 10 mm dowel stuck into a bit of broom handle for a handle. Bits of galvanised steel wire, looks like about 16 gauge, with blobs of epoxy on the ends to protect my eyes and clothing. Folded dipole feed with 1/2 wave balun, but a direct 50 ohm feed is also OK if you design for it, just offset the two driven elements by 5 mm and solder the coax on one side. I’m ashamed to say the elements were held in place with tape, not even glued. I’ve made a similar design for 2 m, thicker wood, using brass TIG welding rods though they were a bit flimsy. It would be easy enough to put them on the same boom.
I use the yagi dimensions from the Antennas In Practice book, here’s the relevant table:
but there’s also QuickYagi if you want to roll your own.
75, Thomas VE7TOA
That’s a great point but the Arrow gives us one more thing: VHF and UHF in one yagi. You can do that with a home-brew but it’s harder. I would love to do a project at the OTC to build a portable satellite antenna.
I’m not excited about the sat station that John XB and Dino built because it’s only available to a few people and at very limited times. I would be very excited about a rig that I can use in a portable kit, which I can take to any park.
I would also hope to keep the cost down so everyone in the club can participate. Projects that cost several hundred dollars are great, but they exclude a lot of members who simply can’t afford such expenses. We have plenty of expensive projects. Let’s have one that costs $20-30.
Yes my construction method is a problem for crossed elements. It would definitely work, just drill holes in both directions and away you go, but then you have an enormous fixed object that can’t be taken apart, wouldn’t fit in a normal car.
Two ways to solve this: 1) removeable elements, but then you have to find a way to get good RF connection. 2) Two yagis held together with some sort of double-sided clips, that can be rotated into the same plane for storage, and at 90 degrees for operation.
If you’re using one radio, the diplexer is another thing you need, in principle for 5 watts it’s just a few small inductors and capacitors but I’ve never built one. This page has a few nice designs that look cheap enough.
@Doug was toying with the idea of hinged elements. That would be elegant for portability.
Hi
The idea I copied from a yagi I bought at a swap neet a couple of years ago. The elements are mounted slightly above the boom on a plastic (3d printed) mount that is bolted throght the boom and held w a wing nut. By loosening the nut the element can be rotated parallel to the boom. Also the parasitic elements can be slid off center so the collaped length is about the same as the boom.
The ant I want to build has a few more elements than the Arrow which will give a bit more gain at the expense of it being a llittle bigger.
I am also considering a design w the same number of elements as the std Arrow.
I still plan to build both, but the project is.9n hold.right at the moment.
Yes but with a flexible wire across the hinge for guaranteed electrical conductivity.
I rediscovered this dk7zdb antenna [fixed link] which claims to have reasonable gain, 10 dBi on 2m and 70 cm, planar antenna 1 x 1 metres with a single feedpoint. It looks amazing, but I’d need to simulate it and then build it for myself to be sure.
I wonder about a take-down plastic plumbing antenna, using:
- mechanical support: thin electrical conduit, that you plug in to a series of cross pieces holes like you would with tent poles. Pipe. Tee. Cross. Also amazon. I think I’ve seen smaller fittings somewhere, 10 or 15 mm outside diameter but these 1/2" pipes would probably work, just a bit bulky
- electrical conductors: 14 gauge ultra-flexible copper wires with silicone insulation a-la “bntechgo”
- elastic at the element tips to pull the wires straight when the element is set up, and allow you to break the element when necessary.
- 70cm elements could be straight metal tubes through the boom.
- choke balun would just be the main feed coax wound around the outside of the same plastic boom…
This could make a $30 dual-band yagi for handheld satellite use, still portable though slightly heavier than the arrow.