vertical antennas

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AE1CT:
will vertical antennas work on am or is a dipole better. what about inverted v antennas? a friend of mine told me that a may pole vertical is a very good antenna to use on am....any thoughts on this topic.

K1JJ:
For 75M "local" work within 400 miles or so, a flat, straight dipole at 40' high (or more) is the best antenna you can get.  Feed it with coax or openwire - it makes no difference in performance except for band-hopping with the openwire.

An inverted vee is a close second, but a compromise because the legs start to cancel radiation as they come closer together. The average height is reduced too.

A vertical will be down maybe 15-20 db locally compared to the dipole. On 160M, va ertical can work well, but is still down to a dipole for local work.

Keep the dipole as far from large objects as possible, like houses, powerlines, etc. Trees are OK and almost invisible. The geometry of the dipole is important. No zig-zags or sharp angles. Strive to make it look like a "T" with the feedline coming straight down to the ground, if possible.  Your radiation pattern will then exhibit the best figure-8 pattern possible. Be sure to erect it broadside to your two favorite directions. (Southwest - NE for example)

Build your own and avoid the gimmick antennas offered for sale. A simple dipole with one center insulator and two end insulators fed with feedline is all you need.  Try to support the center. It will last longer in wind storms. Use 3/16" "aircraft" braided cable to go thru the tree limbs on each end. Rope will break after a short time due to friction from wind.

Do you have the room to erect a full-size 123' dipole for 75M?

Hope this helps.

Tom, K1JJ

AE1CT:
i dont have very tall trees in my yard (30 ft) high and the most room i have is probably 40 meters and i want to get on 80. i want to operate mosty sw from my location and there are no trees that will give me that direction. i want to get on the air but im in a position were i dont have a big yard or the tree hight that i need. WHATS a future AMer to do. any ideas would be greatly helpful.

K1JJ:
In your situation, the next best thing would be to hang a 123' long 75M dipole at 30' high. Stretch the flat legs out as much as possible (65' ?) and then drop the ends down towards the ground on each end. Pull the ends out as far as possible making a slope if you can.  This dipole will look like an inverted "U".  

At 30-40' high, the dipole is mostly omni-directional for local work anyway, so don't worry about the supports and directions for now.


This will work fine on 75M and also on 40M if you wish to feed it with openwire.  Some of the AMers do this and have great signals.   You can even load it up on 160M if you use heavier wire and good quality openwire.  Go to Home Depot and pick up a 500' spool of #10 or #12 black electrical insulated wire. Make the openwire and flat top from it and use a balanced antenna tuner for all band use.  If you use coax feedline, no tuner required, but you are limited to just 75M with the antenna as described.

T

AE1CT:
i was told that i can use a long wire and run it from tree to tree and feed it with 400 ohm ladder line and run a short 20 ft lenght on the open side of the ladder line, sort of like a windom. i mostly want to operate 40, 80 and 160 AM.  will this work for me with some reasonable results, im not looking to be a power house, i just want to be heard and have some fun on AM.

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