600 Ohm Ladder Line vs Coax

[Robb]

Do you have any reasons why you cannot use the ladder line? With a fiberglass mast, you can even just tape the stuff to it, then run it at an angle down to where you're going to run it into the house...

My shack is in my garage; not in the house. The house is oriented lengthwise east to west - and the garage is just west of the house - and the line needs to go to the far west side of that garage - at the base of that palm tree.

18734 Loree Ave - Google Maps
To the left of the picture is a palm tree. My shack is under there - just to the right of it. One can barely make out the IMAX on the garage roof. To the east of it - is the house - where I am planning to put up the fan dipole mounted from the NW corner to the SE corner of that roof. The distance between the center of the roof of the house to the west side of the garage is approximately 60 ft. Plus, the slope from the antenna apex is going to add more length.

The length of this dipole is 82 ft; so it should work well on that roof as an inverted "V" configuration.

How would you set it up?

 

[Moleculo]

You need to water the grass

 

[packrat]

He needs to water the dirt.

 

[Robb]

LOL!
The dog ate it.

 

[Moleculo]

So, are you planning on putting up the mast right in the center of the roof?

 

[Beetle]

Keep the vertex angle greater than 120 degrees and you shouldn't have any problems. Actually for an 80+ foot dipole, finding enough horizontal space to keep the angle that wide is usually the biggest problem on an average residential lot.

 

[Robb]

So, are you planning on putting up the mast right in the center of the roof?

Yes; unless I get advice to the contrary.
Like I said; I'm trying to get this right the first time around if I can.

 

[Robb]

Keep the vertex angle greater than 120 degrees and you shouldn't have any problems. Actually for an 80+ foot dipole, finding enough horizontal space to keep the angle that wide is usually the biggest problem on an average residential lot.

120 degrees - got it.
I'll just have to put the ends up high enough so that will be the case.
I want to be sure that 80 m works well enough; but I also want to ensure that I get an omni pattern out of it so I can work enough DX. The NW/SE mounting was done to make it fit for my location; but the inverted "V" is needed to get the omni pattern from it.
I can do that - thanks!

 

[W5LZ]

I really wouldn't worry about that antenna getting directional at all on 80 meters until it get's to around 65 feet or so high. Dipoles are omnidirectional until they get about 1/4 to 1/2 wave above ground, then they start getting directional a bit.
- 'Doc

 

[Peddler]

You need to water the grass

He can't afford it what with all the radio equipment ...

 

[Beetle]

120 degrees - got it.
I'll just have to put the ends up high enough so that will be the case.
I want to be sure that 80 m works well enough; but I also want to ensure that I get an omni pattern out of it so I can work enough DX. The NW/SE mounting was done to make it fit for my location; but the inverted "V" is needed to get the omni pattern from it.
I can do that - thanks!

Like 'Doc said, any 80 meter dipole less than about 70 feet high is going to be omnidirectional. You don't have to make it an inverted vee, but it won't hurt anything. Now, higher frequency bands may become more or less directional for a given antenna height, but 80 meters will be omnidirectional either way.

The reason behind the 120 degree vertex angle is that the pattern starts to interfere with itself at about that point. You'd be experiencing phase cancellation in really unpredictable directions. At 120 degrees or greater, the patterns at the ends of the dipole can't "see" one another that well, so the pattern remains intact.

Let us know how things go!

 

[Robb]

He can't afford it what with all the radio equipment ...

Yes !!! That's it !!!!

 

[Robb]

Like 'Doc said, any 80 meter dipole less than about 70 feet high is going to be omnidirectional. You don't have to make it an inverted vee, but it won't hurt anything. Now, higher frequency bands may become more or less directional for a given antenna height, but 80 meters will be omnidirectional either way.

The reason behind the 120 degree vertex angle is that the pattern starts to interfere with itself at about that point. You'd be experiencing phase cancellation in really unpredictable directions. At 120 degrees or greater, the patterns at the ends of the dipole can't "see" one another that well, so the pattern remains intact.

Let us know how things go!

I appreciate it - you guys. Must be less than 1/4 of a wavelength on 80m to be omnidirectional. Need all the info I can get to engineer it right...

 

[Beetle]

I appreciate it - you guys. Must be less than 1/4 of a wavelength on 80m to be omnidirectional. Need all the info I can get to engineer it right...

Another consideration: the closer it is to the ground, the higher your losses will be. What does get radiated will generally be omnidirectional, and with a high TOA - maybe NVIS.

 

[Moleculo]

and with a high TOA - maybe NVIS.

...which is perfect for MARS use