Need some advice

[elect1mike]

I want to set up a antenna to use with my hf radio but we are in the process of maybe moving so I do not want to set up a tower then have to take it right back down. How high do I need to place a dipole antenna off the ground for it to work at its best or near best? And is a dipole the way to go or do you have another idea? I was thinking of setting up a pole 20+ feet and mounting my 2 meter/70 cm antenna almost at the top and a antenna for hf 10-80 metetrs on top but I guess I could go higher if I guide wire it.

 

[Beetle]

I want to set up a antenna to use with my hf radio but we are in the process of maybe moving so I do not want to set up a tower then have to take it right back down. How high do I need to place a dipole antenna off the ground for it to work at its best or near best? And is a dipole the way to go or do you have another idea? I was thinking of setting up a pole 20+ feet and mounting my 2 meter/70 cm antenna almost at the top and a antenna for hf 10-80 metetrs on top but I guess I could go higher if I guide wire it.

Higher is better. For a dipole (single band, 468/F), it should be at least a half wavelength high -- in other words, as high as it is long. For things like the G5RV, it should be as high as you can get it, shooting for a half wavelength on the lowest frequency you'll be using. Anything lower than a half wavelength high will not be "...at its best or near best." Also, it needs to be free from buildings, power lines, etc.

And the supporting wires for a mast are GUY wires, not "guide" wires.

 

[elect1mike]

Sorry guy wires

 

[W5LZ]

You asked about the 'best' height, but that's not always possible or practical, and lower dipoles can do more than you'd believe sometimes.
If it's going to be temporary, why not just put up an antenna for the lowest band you want to work at whatever height you can? If I was lucky, the typical HF antenna I had up was maybe 20 feet high, and that was for 80 meters. Nope, not even close to an "ideal" height, but it didn't matter, I did several WAS's with it. It was a sort of 'bent' dipole, didn't have enough room to run it 'straight'. It also wasn't the 'formula' length when finished. I just tuned the thing (adjusted length) till I got a usable SWR. I honestly couldn't tell you what the finished length was, I didn't measure it. You can 'get away' with some really odd shaped dipoles that do work. So... if it's not going to be 'permanent', use whatever 'room' you have and see what happens.
Why the lowest band of interest? Because 'too long' antennas can be 'made' to work on higher bands with a half way decent tuner. A 'too short' antenna is much harder to 'make' work on lower bands. Don't expect 'miracles', but it may work just dandy. Certainly will get you on the air anyway.
- 'Doc

 

[Moleculo]

Since you said this is a temporary antenna, I just put it up as high as you can and still be able to take it down easily and have fun. When you move, you can figure out what is "best" for your new situation.

 

[elect1mike]

Thanks guys I can put one up about 25' no problem so that's what I plan on wish me luck.