need help with my first base

[bigmotorjoe]

im runnning a cobra 29hd edition tweaked with connex echo set it up in my basement w pyramid 14 amp supply 75ft of astatic coax to my attic where i have a 500w dipole antenna set up in a inverted v . im only getting out like 3 mi . i had it horizontal but swr was 3 across the board got it down to 1.2 now any help will be appreciated thanks alot

[Irondog]

I'm running a dipole, also....and I'm finding out that it's fairly directional. Is it mounted inside or outside? I'm curious as to where you have yours and how high off of the ground.

[Cain64]

when is it inside you sre going to lose alot of power and distance partly to the metal flashing used in the attics for roofs.

['Doc]

Some 'givens' about antennas are;
Outdoor antennas will always perform better than indoor antennas. Just more stuff a signal has to go through to get anywhere from inside a house.
Dipole antennas start becoming directional when they get about 1/2 wave length above ground. None of them are 'spot lights', more like 'flood lights'. At less than about a 1/2 wave length height, they are not very directional at all.
There can be quite a difference in signal strength because of polarization. One vertical antenna and one horizontal antenna don't particularly 'like' each other at sort of close ranges. After a signal makes a 'skip', the polarization can change so it doesn't matter a lot, sort of.
If you are seeing an SWR of less than 1.5:1, quit worrying about it, that's about as good as a dipole ever gets, unless the legs of that dipole are 'drooped' a bit.
Power ratings are sort of meaningless with dipole antennas, kind of. It depends on the insulators more than the size of wire used to make them. 18 ga. wire will handle as much power as a '00' size wire, or 1" tubing.
The biggest, or 'best' change you could make is to hang the thing by one end making it a vertical antenna. Not very easy to do in an attic though. An alternative is to make just one 'leg' of it vertical, the other 'leg' horizontal. Sort of like a single radial groundplane.
- 'Doc

[snipe 264]

I just finished a dipole and got the swr's down to 1.7:1 I am going to try to go a little lower. I had mine in a horizontal configuratin but going to try to put her about 20ft more in the air hopefully talk some skip and not just local. I have also thought about hanging it like a single radial groundplane.

[elmer]

my first post but I think I have a good itdea about dipoles

doc is right outdoor antenna's will out perform indoor. you have all kinds of metel in your attic wires nails flashing smoke stacks.
I used a virtical for a long time 1/4 wave with the center at 15feet off the ground but when I put it up at 25feet it worked much better.
not sure about this part of doc's post "Dipole antennas start becoming directional when they get about 1/2 wave length above ground" however the inverted V is a directional antenna wether it's on the ground or 2 wave up. virtical is the way to go for local talk, skip talk thats a nother game.
check out wikipedia there is a lame little picture that shows the radiation pattern of a moving dipole. notice as the diple folds you loose the radiation on the back side.


my dipole I tossed a rope over a tree and attached one end to my element and hoisted it up it just hung there.

dipole is a good place to start with a new rig or low cost setup but i'd say just save your $ and pick up a base station 11 meter antenna. I've also talked to a guy on a K40 that was mounted on the aluminum trim on his house. he used a L shaped mount and just screwed it to the peak.

[Night Crawler]

not sure about this part of doc's post "Dipole antennas start becoming directional when they get about 1/2 wave length above ground.

He's right.
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[Irondog]

It's strange how well my dipole is working. I have it actually hanging from my ceiling fan in my bedroom in an inverted "V". The "legs" are attached by string...one to an exposed carpet tack against a wall and the other by string to the bottom of a clothes hamper. LOL...I know...it's a strange setup...but temporary. But I have now talked 10 miles that I know of for sure....and the guy said my audio was crisp, clear and hitting him strong. I live in a trailer that's had rooms built onto it...so there is a lot of metal that I would think would cause problems. I have an SWR of about 1.1...great. My Uniden Washington is keying around 3 and swinging to 12. I haven't done any tuneups or any other mods to this radio...yet.
I live in Branson, MO and anyone familiar with the area will attest to the fact of all of the Ozark Mountains that surround it. I have some major "hills" all around me since I'm basically in the bottom of a holler.
Oh yea....the dipole is made with a short piece of pvc with a connector in the bottom...then the leads are kept separate...one going to the right and the other going out the left side of the pipe (about 4 inches long and capped). Then I used two pieces of 8.5 foot stranded copper wire for each side. I can't complain...it works great. I have 50 foot of coax and have it looped like a balun hanging from the bottom of the connection.
Thought I'd kinda clarify how good this temporary setup is doing for me.

[elmer]

hmm not that I am saying your wrong but the qsl site is a 0 deg Azimuth. that means it's a horizontal dipole right? and in that case ALL horizontal dipoles are directional. as the plots show if you have it close to the ground it acts all most like an omni. a virtical dipole will transmit in a donut shape around it's feedpoint no matter the hight, a true omni. as you bend it's legs to form your V shaped or L shaped dipoles the pattern changes yet again. horizontal dipoles are an odd duck and will give your metters misleading reads normaly at less then 5/8 wave. I have a horizontal right now at 25 feet with a 1:1.5 swr my metter is showing 675 watt at 27.385mhz but my amp only puts out 525. this is caused by radiation reflection from the earth. you can find the 3d dipole patterns all day long if you google it. you will see the same donut shape around all straight dipoles. the horizontal patterns change from the radiation reflection that your transmiting right at the ground. try it some time find your self a 1/4 or 1/8th wave loaded whip and put it in the bed of your truck and open the tail gate. the radiation will bounce all over the bed of your truck till it finds the open tail gate and bam you have a directional virtical antenna. the point is any omni antenna will become direction at any hight if you place it next to a good ground and the patterns and plots will change depending one how close that ground plane is.

['Doc]

Antenna radiation patterns can be very confusing depending on knowing how they are derived. The 'free space' patter for a dipole resembles a donut, the dipole running through the center, the 'ring' oriented to the sodes of that dipole. The classic 'figure eight' pattern is what that donut looks like if you just cut it straight across parallel with the ground. That's fine, and does give you a very general idea of what that radiation pattern can look like. With the newer way of doing graphics (computers), more 'things' can be taken into consideration when generating one of these radiation patterns (@#$$ of a lot faster than doing it by hand, right?). If you think of 'ground' as a mirror, things can be imagined easier. How conductive the ground is sort of corresponds to how 'dirty' that mirror is. If it isn't very conductive, things get sort of 'fuzzy', if that makes sense, and the resulting radiation pattern changes to something not as 'ideal' as it was, sort of. Huge variations in thinking of it in that way, none of them completely accurate. If reflectivity/conduction is better in 'spots', then the resulting radiation pattern get's sort of 'lumpy'?
What it all boils down to is that a 'classical' radiation pattern is almost never achievable, just close, sort of. Depends on where the antenna is, how high, what's around it, and at times I think, the color of the @#$ conductor used. An accurate duplication of a particular pattern (different location) means duplicating everything that was present in the original set up. If you EVER figure out how to do THAT, please let me know??
- 'Doc

On second thought, I'm not too sure I wanna know.

[drdx]

Actually, they are BI-directional. I think what doc was getting at was that ground proximity plays a big role, and low ones don't usually have the classic pattern. If you have the means, 2 dipoles, one oriented n-s and the other e-w, or simply 2 that are perpendiculer to each other will give you nice switchable horizontal coverage. Do that setup under a vertical, using a 3 way switch that grounds unused antennas and you have a very effective poor man's setup.

-drdx

['Doc]

There are always a bunch of "but's" involved in anything you do. The idea is to minimize those "but's" to get the best return for whatever it is you're doing. That holds for antennas just like anything else. (I could afford a new 'Vette, but can't afford the insurance, you know? RATS!)
The basic idea for antennas is to radiate the signal sent to it in the best way it can. That 'best way' thingy includes direction, and distance. There are limits though. Particular 'sized' antennas tend to have particular characteristics which don't change until the 'size' of that antenna changes too. A rubber-duck antenna will radiate, just like a 5/8 wave antenna will radiate. It just ain't gonna get as far. Has the same ability in direction, just not distance. Doesn't really matter how much power you feed that rubber-duck, it just ain't going very far when compared to a larger 'sized' antenna. Smallness makes a difference in capability and convenience, but not ability. If you have to use a particular 'size' antenna for whatever reason, you are limited to it's capabilities no matter what you do.
So, the 'trick' is to optimize any particular antenna as much as possible. The three things that will make the most difference when doing that 'optimizing' is making the thing appear to be resonant (get rid of all the reactances you can), make it's input impedance compatible with the rest of the antenna system (feed line and radio), and put it as high as possible. In the case of directional antennas, add pointing them in the direction you want. Lots of 'wiggle room' in all that. When it gets to the point where it does what you want (with in reason), it's time to quit messing with it. If the results aren't what you wanted, then start looking for another antenna, or see if you can improve what hasn't been 'improved' yet. The overall limit is practicality. I just don't have the ability (space, property, finances) to put up the "best" antenna in the world (whatever the #$%% that is!). So, I make do with the 'best' that I can do. Which falls in that "with in reason" thingy. Uh ... unless I win the lottery, right?
The only 'mystery' in any of this is which antenna 'type' will fit you the best. After enough research and a 'SWAG' or two, you will eventually find it. Happy hunting!
- 'Doc

[elmer]

well said doc... back to topic 1. put that thing out side. 2 for local talk go vertical. 3 put it up in the air. and if you wana talk skip do some googling lots of info on it out there.

"happy hunting!" !