BD4WCL I saw some portable bamboo structures made of two units online and thought about making one myself. My initial idea was: Use 2020a square aluminum material as the main beam. Unpowered oscillator: Connect the transducer using connectors, with a 5.6-meter pull rod. Active vibrator: Two small arms, made of square aluminum material, are also used on the left and right sides of the main beam. Each small arm has two connectors that connect to a single M10 connection point. A pull rod is then connected to each M10 connection point. Finally, a ready-made barrel is used. Using a 4.8-meter light stand and a video light stand adapter. Use rubber insulation pads for both the oscillator and the aluminum to provide insulation. I will also provide pictures of these parts later, as they are not available on Taobao. The problem I'm facing now is that I don't know the specific length parameters for this Yagi antenna. I hope you can all help me. Most importantly, I would appreciate any advice from experienced individuals. Thank you very much!
BD4WCL The current progress may need some adjustments. The two units are a bit unusual, so the plan has been changed to three units instead. The other aspects remain unchanged for now.
BH6QCE The pull-down effect was particularly severe. I tried a three-element Yagi antenna, but it only provided a bandwidth of 12/10 meters. The remaining frequency bands were unusable due to excessive attenuation, resulting in excessively high standing wave ratios. Specifically in the 20-meter band, almost all of the antenna was extended, drooping like a fishing rod. Therefore, I recommend using a 1.2-meter aluminum pipe. If you absolutely need to use a pull rod, then the pendulum should be suspended at an angle to counteract the downward force.
BH6QCE BH6QCE And I assume you've also considered portability, since you've divided your main beam into eight sections… The poles are already 1.2 meters high, and one electric piano case can solve the problem.
BD4WCL BH6QCE If you were to pull it with a rope, that would be a very large undertaking.😂I want to use it on a 20-meter wave, but I need to figure out how to do that. I'll have to rethink the design and create a pulling mechanism to keep it parallel.
BD4WCL BH6QCE Another concern is that if I were to use it in the 20-meter band, the main beam would need to be 9 meters. I'm now wondering whether my main beam will bend under such conditions.
BH6QCE My three-unit trolley (now in a 10-meter configuration) ↑ has now been completely replaced with aluminum pipes. The main beam is made of 2020 aluminum profiles, measuring 3 x 1.2 meters.
BD4WCL BH6QCE The main reason I'm considering it is portability. Adding a few more aluminum tubes would make it too heavy and difficult to set up. Now, I'm wondering if I can add a stand on top of it? To attach the wind rope.
BD4WCL BH6QCE Also, how do you achieve impedance matching? It seems like I can't directly connect a resonant circuit to a Balun; my knowledge of antenna matching is still lacking.
BH3XZT Someone in Area 8 has done this successfully before, and you can search for it on Bilibili. I've forgotten the exact name of the video.
BH6QCE BD4WCL 9-meter aluminum profiles? Bending allowed. My incentive valve, directly connected to the barrel, had an M10 expansion screw installed at the bottom end of the aluminum pipe. By connecting to the insulated end via terminal blocks, power can be supplied. Since it's a 50-ohm design, a direct 1:1 balun is sufficient.
BH6QCE For reference (I was just wondering if using a 9-meter main boom for two or three Yagi antennas is really necessary)
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