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Best Dipole Setup

codeman said:
I use two cheap fiberglass antennas, I think they are Mobile Tronics brands or something like that. I 've used one on my pickup and it did a great job. It really pulled in the weather channels. I am able to get weather bands from 70-90 miles away with it. Anyway they have rings that loosen then you just unscrew or screw in the tip to set the swrs. Makes it easy. I may try it at 6ft. just to see what happens. I also run a dr.dipole antenna in an inverted v at about 10-11 ft. at the feedpoint. When skip is rolling i can make some decent contacts. The inverted v works much better for local talk as it should.
I live in a townhouse with a small patio, so I have been trying to have my fun with the radio while not stirring up the neighbors. Trying to keep it as stealth as possible.
I have been thinking about putting the dipole up to 18ft. to see how that would work. I am gone 4-5 days on the road so I don't have much time I would like at home to mess with the radio and antennas.
Click to expand...

The resulting SWR at 6' might be a little lower as the article I referred to suggests, but for actually making contacts, I have to agree with Paul. Higher wins. I've tried time and again to disprove this because of the convenience of mounting low but they were just visions of grandeur. Am giving up.

That doesn't mean I'm mounting mine high. I can't. Just have to do the best I can and hope for good conditions. o_O

PS Love the car in your avatar!
 
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From the article:

This is not the ideal DX antenna, but it does provide good signal strength at reasonably low angles (6 dB down at 20 degrees elevation angle). It is essentially the same pattern as the .25 wavelength height dipole, but with the benefit of being matched to 50 Ohms. In addition, it provides a very broad NVIS signal lobe. This looks like a good compromise between both modes, and is fairly easy to set up on frequencies above 10 MHz.

and

According to the above article, The Best Dipole Setup is somewhere between 20% and 15% wavelength height, where a dipole's impedance crosses 50 Ohms.


which is it? a low angle DX antenna or an NVIS antenna?

I'm really glad:rolleyes: that it radiates about like an antenna that is mounted @ .25wl:ROFLMAO:


NVIS at" frequencies above 10 MHz"....................NOT!

BTW, This is written by the same guy that sells the 2 meter antenna disguised as roofing vent pipes.... they are really just 50 ohm dummyloads too;)

Bottom line, for DX get it up at least .5wl (or higher).
 
DainBramage said:
BTW, This is written by the same guy that sells the 2 meter antenna disguised as roofing vent pipes.... ;)
Click to expand...

And read by the same guy who puts antennas in an attic surrounded by a AC/Heating unit, foil ducting, tin vent pipes, Christmas decorations, and miles of electrical wiring and expects great things from it. Me!

Pretty sure I'd be better off finding a new hobby. Scientific fact and me don't get along.
I prefer wishful thinking and outlandish hopes.
 
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here is some good and correct info: http://www.w8ji.com/nvis_n_v_i_s_antenna.htm

notice this quote: "Please, let's not give silly advice like 5-foot high antennas are good ideas for emergency communications or NVIS operation. Very low antennas produce very low signal levels at any distance when compared to antennas of modest height."...
 
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Just a note or two.

First off, hey doc, its good to see you posting again. I have seen you around thus far and haven't said anything yet, so now I did.

Riverman71 said:
According to every chart I've ever seen, an SWR of 1.2 typically results in a power loss of .8%, leaving 99.2% power available at the antenna. For an SWR of 1.4, it is 2.8% and 97.2% respectively.
Click to expand...

Those charts are wrong about something. What SWR does is actually reflect a certain amount of power. That doesn't mean that said power is completely lost.

Take a look at the video I posted in this thread at about 41 minutes and 10 seconds.


The DB
 
DainBramage said:
here is some good and correct info: http://www.w8ji.com/nvis_n_v_i_s_antenna.htm

notice this quote: "Please, let's not give silly advice like 5-foot high antennas are good ideas for emergency communications or NVIS operation. Very low antennas produce very low signal levels at any distance when compared to antennas of modest height."...
Click to expand...

Thanks. Have seen that before. Was hoping it was written by some guy who sells flowerbed ornament antennas. Judging from the author's website, it wasn't. LOL.

Am having a senior moment. If an antenna is down 13 dB when compared to another, what exactly does that mean?
 
The DB said:
Take a look at the video I posted in this thread at about 41 minutes and 10 seconds.
The DB
Click to expand...

That is a great video. Saved it when you first posted it.
Just watched part of it again. Doing so is similiar to planting a tree.

What's the best time to plant a tree? Twenty years ago.
Second best time? Right now.

Wish I'd watched this video twenty years ago. Heck, forty.
I understood and retained much better back then. :D
 
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Riverman71 said:
... If an antenna is down 13 dB when compared to another, what exactly does that mean?
Click to expand...

I can't post the chart I want to post, go here and look at the chart... if you signal is 13 dB down, it has lost about 95% of its power.

Every time you double (or halve) the power level, you add (or subtract) 3 dB to the power level.
This corresponds to a 50% gain or reduction.

10 dB gain/loss corresponds to a ten-fold increase/decrease in signal level.
A 20 dB gain/loss corresponds to a hundred-fold increase/decrease in signal level.
In other words, a device that has 20 dB loss through it will lose 99% of its signal

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwjE54C6hOzVAhXjxFQKHaHyBJwQFgguMAE&url=http://www.fab-corp.com/pages.php?pageid=5&usg=AFQjCNHHwPOVBILOW4cRDNryD0hY70ON6w
 
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Reading threads like this and associated today. After six weeks on the road am taking today off.

Off being more like reviving the idea seen elsewhere of truck drivers using a Vertical Dipole. Claiming success.

I haven’t gotten drunk yet, am reserving that excuse for monkeying with two different mounts. One an MFJ-347, and the other simply using two mounts on the “bar” which bolts to the body (can do a 45-degree — whatever — with the non-powered whip).

The readings a pleasure.

Like Riverman, I get by because I can put “them” in a far better light than they deserve. Like the wetback that stole an $85 antenna off of my truck yesterday. Does it really matter which one takes the blame?

(Nope. Don’t mess with me. Horizontal ain’t yet on the menu. Need that downhill and uphill march, first).

.
 
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A few notes.

That table has the % diff and dB diff backwards. For example, 1% loss is not 20.6 dB loss, but 1 dB loss is about 20.6 % loss.

Another problem to consider, the info under the chart treats loss and gain as the same, however, the percentages are actually different with losses and gains. The chart above is only close to being accurate for losses.

Examples of what I am talking about.

1 dB loss is about 20% below the starting power, however, 1 dB in gain is closer to 25% above
3 dB loss is about half (50% below) of the starting power while 3 dB in gain is double the starting power (100% difference)
10 dB loss is 1/10 (or 90% below) the starting power, while a 10 dB gain is 10 times (1000%) over said starting power.

Here is a link to the one I like to use, make sure you use power and not voltage as the results will be different.


The DB
 
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The DB said:
A few notes.

That table has the % diff and dB diff backwards. For example, 1% loss is not 20.6 dB loss, but 1 dB loss is about 20.6 % loss.

Another problem to consider, the info under the chart treats loss and gain as the same, however, the percentages are actually different with losses and gains. The chart above is only close to being accurate for losses.

Examples of what I am talking about.

1 dB loss is about 20% below the starting power, however, 1 dB in gain is closer to 25% above
3 dB loss is about half (50% below) of the starting power while 3 dB in gain is double the starting power (100% difference)
10 dB loss is 1/10 (or 90% below) the starting power, while a 10 dB gain is 10 times (1000%) over said starting power.

Here is a link to the one I like to use, make sure you use power and not voltage as the results will be different.


The DB
Click to expand...


Something wrong with that page.

Where are the, This old weird trick cures . . . “, ads?
 
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