Amateur Radio Bike Mount for Vertical HF Antenna

thingiverse

Attach a mast to your bicycleThis project enables you to attach a fishing pole or another fiberglass pole to your bicycle. My mount is designed so that it can be secured with zip ties to a location where a rear trunk bag would normally fit.Assembly and useYou need at least 4 M4 screws with nuts to assemble it. Base is designed for a 32 mm diameter mast but it is easy to use adapters or modify my project (I attach a FreeCAD project). Personally I use short piece PVC pipe which is tight fitted into the mount and if I want to take mast with me I just put collapsed fishing pole into the pipe and when I stop in order to operate I can telescope it in few seconds.At the bottom of the mount I have placed a slot for a PL-239 UHF connector. I advise you to also print a protection cover for that connector so that water and mud will not get into it.Four holes at the bottom of the base mount are meant to drain any water in case you will ever get caught in the rain.The antenna and ground radials can be attached using M4 crimp terminals or lugs. I use M4 nuts with 3D printed attachments that allow for easy hand connection and disconnection, without the need for a wrench. The best option would most likely be to use butterfly-type nuts.Finally there is also a spot for a impedance transformer or BALUN. Something like 1:9 or 1:64 would allow you to install an end-fed or LW to your bike.About the vertical and radialsRemember that a low SWR on a vertical antenna does not necessarily mean that the antenna is efficient. It can also indicate that you are losing power into the ground.I have tested this antenna in the field with four 10 meter long radials. It worked with a very good VSWR (<1.4:1), but with an ideal vertical antenna, you would expect to be closer to a 2:1 VSWR. The number of radials should not significantly affect your resonant point, though.Personally I have used it as a vertical which on 20 m was exactly 1/4 wavelength.It fits smugly with my trunk mount but I cannot guarantee that it will work for all of you since I don't expect this things that these things are standardized in every part of the world. Feel free to remix it to fit other bikes. This is open source project after all!I DO NOT recommend riding with the pole fully extended.Loading coilI have used this adapter with a 5-meter fishing pole, and it worked great, even during windy conditions. On my profile, I also have a coil former that can be attached to the mast. It also has screws for quick connection to the antenna. With that coil I had no problem working 40 m band.Enjoy the radio,73 de SP6GK