Hello everyone. Though it's not quite done yet, I wanted to share my most recent project: A 900mhz FPV groundstation.
I wanted to build a long-range antenna for my 900mhz FPV system. I was very inspired by David Windestål's "overkill" FPV groundstation, but didn't have any G10 fiberglass or a CNC machine. What I did have was oak, so I decided to go with a slightly different aesthetic--an aesthetic that says "I'm Captain Nemo in a cowboy hat".
Almost all the wood used for this build is 1/4" oak, milled from a tree that fell on a friend's property. The handles are made from some oak chair legs I found at Home Depot. It's held together pretty much entirely with 2-part epoxy. I designed the grip to emulate that of a chainsaw, which is also a heavy tool of a similar shape that must also be wielded with extreme precision.
I built the antenna using I.B. Crazy's guide. The helix is 3/16" copper tubing and the reflector plate is made of aluminum with copper foil laminated to both sides. I could've used a solid copper plate, but this would've been heavier and much more expensive. I had originally intended to use bare aluminum, but found that impossible to solder, so I decided to laminate it with copper for practical and aesthetic purposes.
The copper pipe endoskeleton not only provides handles with which a spotter can aim the antenna, it also protrudes from the bottom to form a support. This serves two purposes: It keeps the weight of the unit from resting on the delicate reflector plate, and it cants the antenna up at an angle so it can be used just sitting on the ground.
Yes, it's a jumble in there. I'll try to hit all the major points of what's going on; I've got two 900mhz receivers, one hooked up the the helical antenna and the other to a SMA female port on the top of the box (currently outfitted with an omnidirectional CP antenna). The red circuit board is a Range Video diversity controller. At the back, you can see a gold panel mount plug; this is a stereo plug I've wired up to send power and signal to my screen or goggles via just one 3.5mm stereo cable. It's also got 10 amber LEDs which were originally supposed to function as a power meter but ended up simply as an indicator lamp when it became clear that my knowledge of circuitry wasn't up to the task.
The side panel is held on with magnets that secure to the 4 steel tabs at each corner of the enclosure.
Here's a shot of the rising sun ornament with the LEDs lit. Also seen is the newly-installed knife switch, which isn't in the other images.
This is a close-up of the antenna connection and impedance matching solution. I did an impressively awful job soldering it, but for all that, it works phenomenally. The range and penetration is vastly greater than what I was getting with the omnidirectional antenna.
Finally, I wanted the unit to be fully tripod-mountable, so underneath the plate for the receivers there's a T-nut threaded to accept standard tripod mounts. The thing weighs 7 lbs. (3 kilos) and it's a little ungainly, but it works.
And when I'm not using it for flying, it's a great costume piece!
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