Longwire

[unidenjim]

Hello, i first got into radio listening to shortwave broadcasts. started with the silly telescopic antenna. frustrated with indoor reception and interference, i strung magnet wire between two trees, connected to a balun, one side to a ground rod, the other to some cheap and available tv 75ohm coax, to a tiny balun, and the results since then have been above acceptable, all previous problems gone.

anyway, now that i have finally got a transmitter, i want to use that long wire in the tree and try to transmit. i already have run some 50ohm coax outside.

the owner's manual for the transmitter says 50ohm unbalanced. i also kind of understand that the longwire in the tree is also considered unbalanced. will it be safe to transmit on the longwire if i put a UNUN in between? also, what about the longwire length? I would say it's about 20 feet high, maybe 30 feet long. ground spike 6 feet down.

how do i know what "direction" the beam will transmit according to the orientation of the wire to the ground, unun, radio, etc? the end of the wire opposite of the unun and ground is south east. where will the rf be strongest?

 

[prcguy]

A "long wire" antenna is defined as being many wavelengths long and 30ft at 27MHz is less than one wavelength. If you make the wire about 36ft long or a full wavelength it would have a four lobe clover leaf radiation pattern at about 45deg angles to the wire with a tiny bit of gain. The impedance of an end fed full wavelength is very high impedance around 2500 ohms and you would need something to match it like a 49:1 transformer which is easy to build.

This antenna would be ok for skip if one of the four lobes happens to be pointed at the distant station. Problem is you can't rotate your house very easily to repoint the antenna. It would not work very well for talking to locals using a vertical antenna.

Hello, i first got into radio listening to shortwave broadcasts. started with the silly telescopic antenna. frustrated with indoor reception and interference, i strung magnet wire between two trees, connected to a balun, one side to a ground rod, the other to some cheap and available tv 75ohm coax, to a tiny balun, and the results since then have been above acceptable, all previous problems gone.

anyway, now that i have finally got a transmitter, i want to use that long wire in the tree and try to transmit. i already have run some 50ohm coax outside.

the owner's manual for the transmitter says 50ohm unbalanced. i also kind of understand that the longwire in the tree is also considered unbalanced. will it be safe to transmit on the longwire if i put a UNUN in between? also, what about the longwire length? I would say it's about 20 feet high, maybe 30 feet long. ground spike 6 feet down.

how do i know what "direction" the beam will transmit according to the orientation of the wire to the ground, unun, radio, etc? the end of the wire opposite of the unun and ground is south east. where will the rf be strongest?