Making a 75' bamboo antenna for HF or 25' horizontal long wire - Page 1
Forum section: electronics / rf-microwave

author: Beamin
author_rank: Super Contributor
timestamp: October 23, 2017, 09:00:47 am
content: I live on a hill with a steep back yard. I like to listen to HF and will be getting a forty meter WSPR TX and RX. The lots not that big but the house is huge.So this is what I came up with. I found some bamboo trees behind the house they are about 3" around and are perfectly straight 24' poles. So what I was going to do was take three of them join them together end to end and plant one end in the ground and use a rope or something to pull it vertical. I would like a HF gen purpose to run along the side and add coax on the side with a 2 meter vertically polarized dipole that will be at the top 80-90 feet high with a skinnier bamboo sticking out the top.Or should I take three 24' trees stick them vertical with 25' between them and run a coax feed line up one and string a long wire antenna from the tops like they do with AM broad cast radios??Does the antenna get messed up if the coax connects to the long wire at the base of the antenna? I'm also not sure if I should do a 1/4 wave length or what. I'm about 10 miles away from the site where half of the tv /fm broadcast antennas are so I have to keep that in mind. I'm also running an unun (9:1 or 1:1 it has a 3/4" ferrite core) where ever the coax turns to wire, and a 4' copper pipe as a ground rod at the base.I only have enough wire to make one so I dont know if it should be an 24-50' tall inverted V, a very tall "whip" antenna; or a horizontal antenna strung across the top.Free antenna masts and they are carbon nuetral blend in and biodegradeable. Just sucks I need to find more bamboo to cut down when I move.I think living on a hill with a 90' 2m antenna would kick ass. I wish I was able to mount it on the roof of the house it would be about 150' above the ground and hundreds of feet above all terrain for a few miles around it. MY beofueng will be so happy!

author: Beamin
author_rank: Super Contributor
timestamp: October 24, 2017, 05:02:37 pm
content: pics....

author: cdev
author_rank: Super Contributor
timestamp: October 25, 2017, 06:38:56 pm
content: Bamboo is potentially a very good antenna support. Its very strong and also very elastic.It also sometimes grows very fast and puts out roots to expand into new areas very fast.Growing bamboo shoots exert tremendous pressure on things like masonry and concrete landscaping, paths, etc.It can get very well established and sometimes it can cost an incredible amount to stop (it from encroaching upon housing and yards and possibly damaging buildings as it grows up.) It can become an invasive plant.So keep that in mind.

author: radiogeek381
author_rank: Regular Contributor
timestamp: October 26, 2017, 01:52:18 am
content: Great project!The neat thing about WSJT and even PSK31 is that you don't need to be a powerhouse to make some contacts. (The same is true for all modes, actually.)Inverted V is a pretty good choice. Is there a particular reason that you are concentrating on 40m? For WSPR, 30m and 20m are reasonably active and provide some very interesting patterns.In any case, the performance of most antennas improves dramatically when they go from piles of wire on the ground to stuff hanging in the air: there is a lot to be said for "cut and try" especially when it comes to HF antennas. (First principles analysis and antenna modeling programs don't do well at accommodating the complexities of a hill with a house on it, and trees, and leaves, and wind, and rain, and two bicycles in the yard, and so on.)The bamboo tripod sounds like a neat platform for lots of experiments. Start simple, and get an antenna tuner. You'll be surprised how well non-resonant systems work (as long as you have a sense of humor, keep the transmitter clean, and recognize that the coax is now part of the antenna).

author: Beamin
author_rank: Super Contributor
timestamp: October 26, 2017, 05:15:14 pm
content: Quote from: cdev on October 25, 2017, 06:38:56 pmYes well I'll be cutting a lot down because home depot is stupidly over priced when it comes to that stuff and transporting when you don't own a truck is unreasonable.I chose 40 meter because I just happened to order a DIY 40meter low power transceiver and saw some youtube videos by dave casler on his 40 meter set up. I have an analog swr meter will that surface until I get an analyzer?Another question will a 1/4 wave work as well or close as a longer multiple? 40 meters is a lot of space and a lot of wire. Is there a preferred for transmitting or receiving? Once I put this up I don't want to have to overhaul the whole thing multiple times because I have a bad back and have to get someone to put it up for me. I have a lot of coax that I can work with too. I think the majority of it is 50 ohms RG6 it was free and I plan on splicing the longest ones together not ideal but cost wise its best.