Dipole Configuration

[blkhwkdr]

I plan on taking my morse exam next weekend. <fingers crossed> To finish my upgrade to a General ticket.

I have a 40 meter CW qrp rig setup w/a dipole just for listening and copy practice. I'd like to ask about dipole antenna configurations.

Currently it's just loosly strung along the roof eave outside about 8 feet off the ground.

I understand what horizontal does and inverted V I sorta get.

But when I read that sloped, which would actually be the best, space wise for me, is directional, does this mean I will lose alot of the DX I could hear from the sides, if I was say, flat or V mounted?

I'm new to the whole Ham group, and working like crazy to upgrade to General. Theory in a book is harder to understand than good ol plain Elmer advice.

Thanks a million and 73

 

[Captain Kilowatt]

A sloped dipole ,or sloper, will have a slight directivity if the support is metal like a tower etc.This is only about 3-6 dB or about one S-unit.If the support is a tree or other non-conductive material there will be essentially no directivity at all.Once you start adding resonant lengths into the mix then things will change but for a simple sloper dipole you need not worry about missing out on signals from certain areas.

 

[blkhwkdr]

So in effect a simple dipole will be almost identical in performance in any configuration if it's mounted outside the higher the better?

 

[Hamin' X]

A dipole is by it's nature, directional. It's TX/RX pattern is to the sides, not off the ends. If your dipole is mounted vertical, then it be comes omni-directional Higher is better, but you will do fine if you can get a horizontal dipole up 1/2 wavelength minimum. The inverted V is more non-directional, and does not have to be as high to perform well.

Rich

 

[W5LZ]

Rich,
A horizontal dipole being directional depends on a number of things, height above ground, it's configuration, and what it's close to. At below something on the order of 1/4 to 1/2 wave length above ground it isn't very directional at all, about as directioanal as a typical vertical antenna.
Especially at HF you wanna take the directionality of an antenna with a fairly large dose of 'salt'. There are no ~very~ directional HF antennas, they're more a 'flood' light, rather than a 'spot' light sort of deal until you get into multielement, huge, almost impractical things which most people don't have the room and $$$ for.
'blkhwkdr's antenna is probably 'sorta' directional, but only because it's near something (house), the height not really 'counting' because it's so low. It's radiation pattern is probably sort of 'egg' shaped rather than round (if that makes any sense, it's early, not enough coffeee yet).
I can think of one type/style antenna that doesn't depend on height much. It's at least twice as long as any dipole, not a very 'simple' antenna to make, requires other parts besides just wire, and also has an input impedance that isn't anywhere near 50 ohms. I've had/used two of them. Wish I had another. Ain't gonna make another one, and am too cheap to buy one (if I could find someone making them). It isn't a very common thing, is called a "C.C.D." antenna (Controled Capacticance Distribution), and is 'different'. Wish I hadn't brought that up...
- 'Doc

 

[blkhwkdr]

Thank you Doc and Rich and Hamin,

Those 3 paragraphs turned on my brain light switch.

I GET IT!!!

Jester

 

[Hamin' X]

Doc,
Your points are well taken and that is why I specified a 1/2 wave dipole, at 1/2 wave minimum height. Not only does the height above ground affect directivity, but droop, sag, angle, ground conductivity, nearby objects and a host of other factors, play a role. These things can, also affect the feedpoint impedance. I figured that keeping it simpler was a better starting point for Jester, as he indicated that he is just beginning and shows a desire to figure it out.

Jester,
Most antenna installs are a compromise. For example, the 1/2 wave minimum height. On 40 Meters, that is 70 feet, not really practical for most folks. I suggest that you beg, borrow, or buy an ARRL Antenna Handbook. Read through the theory part first, then throw up a wire and load it up. You will be surprised at what works. The point is, put up something, then learn how to improve it. Knowledge acquired in this manner will last a lifetime.

73, Rich

 

[Beetle]

Jester - don't be afraid to experiment, either. If Marconi and the other early radio guys hadn't done some experimenting, we'd be a lot less "evolved" than we are now. And they didn't have antenna analyzers and the Internet to help them.