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Dual Antenna's Question

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DualAntennas

New Member
Oct 6, 2013
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My main goal is to be able to talk to truckers going down 3 OR 4 express-ways around my house. one e-way is 3.6 miles from my house and one e-way is 7.8 miles from my house.
What effect would Running Dual Antron-99's have?
Example one on each side of my ranch home?
So they would be way more than a wave length apart.
I heard on a forum they would cancel each other out if spaced this far? Is this True?
Would it shorten my range?
 

Dual antennas will have more gain in two directions, on the broadside in both directions. You will also have to build a cophasing harness to correct the impedance mismatch. You can have them much closer than 1 wavelength if you go this route. Truckers use dual antennas; but a base station doesn't need to do that.

Honestly, I don't know why you must take this course. If you had just one antenna up high enough it would work just as well and be truly omnidirectional. Which -IMO - is best for local communications anyway. Thirty feet up should be optimal; higher is still better too.
 
Sometimes one antenna is better than two and this is one of those times. Running phased antennas requires some knowledge regarding spacing and length of the phasing line that connects them to the transmitter. One antenna has to have the proper delay in order to work right IOW the signal must arrive at each antenna at the proper time. Simy picking a distance to space them lime each end of the house makes it really hard to determine the proper length of coax to use as a phasing line. Picking a known exact length like a halfwave or even a full wavelength makes it much easier to determine the length of the phasing line.

I would stick with one antenna up as high as you can get it.
 
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I ran a few models with the 4nec2 modeling software to see the radiation patterns for two end fed half wavelength antennas 5 meters high over "real ground" at various distances apart. They are also in phase. This is what I found...

1/2 wavelength apart...

1.jpg


5/8 wavelength apart...

2.jpg


3/4 wavelength apart...

3.jpg


7/8 wavelength apart...

4.jpg


1 wavelength apart...

5.jpg


At a half wavelength apart there are two lobes broadside to the pair of antennas. As you begin to spread the antennas apart from there the existing lobe begins to shrink as new lobes open in line with said antennas (on the X axis). These lobes continue to get larger, and if continued past the point shown here begins to split into two lobes each.

Because of this the distance of separation matters. If you are looking for two deep nulls 1/2 wavelength separation is your best bet. If you are looking for maximum gain in two directions 5/8 wavelength apart is your best bet, although a 3/4 wavelength separation will yield 0.06 dB less gain, this is insignificant and will not be noticed by anyone.

These look just like the diagrams shown in the last few versions of the ARRL Antenna Book for antennas with similar spacing apart. It was listed in said book to be for quarter wavelength antennas and these models are of half wavelength antennas. I guess size does not make much of a difference here.

Well there was my first modeling project... I learned a thing or two in the process and hope it is of help.


The DB
 
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Shakesphere 176-1 VS. Antron-99

Now for the choice...

Shakesphere 176-1 VS. Antron-99

I've also considered the Maco V-5000

Which of the 3 is best for my circumstances???

one e-way is 3.6 miles from my house and one e-way is 7.8 miles from my house.
The E-ways make a circle around my base station
Keep in mind limited Budget Here
 
DualAntennas said:
Now for the choice...

Shakesphere 176-1 VS. Antron-99

I've also considered the Maco V-5000

Which of the 3 is best for my circumstances???

one e-way is 3.6 miles from my house and one e-way is 7.8 miles from my house.
The E-ways make a circle around my base station
Keep in mind limited Budget Here
Click to expand...

If you are on a budget; then why get two antennas? Not practical in that regard. If you could spend that much I would consider getting just one decent antenna, and I don't mean an A99.


I would get a Sirio Vector 4000, put it up 25-30ft, get a pre-made length of quality coax like RG-213 with the connectors on it to feed it, and you should be off to the races with a setup that will transmit and receive with the best of them - IMO. Just make sure you support the antenna well with guy ropes and do not install it where it could fall over on power lines if high winds should happen. Pretty much it.
 
Last edited:
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DualAntennas said:
Now for the choice...

Shakesphere 176-1 VS. Antron-99

I've also considered the Maco V-5000

Which of the 3 is best for my circumstances???

one e-way is 3.6 miles from my house and one e-way is 7.8 miles from my house.
The E-ways make a circle around my base station
Keep in mind limited Budget Here
Click to expand...

I guess I'm not understanding what you are trying to accomplish. If the expressways all circle your home base, I would assume you wanted to transmit to all of them, in a circular pattern. You could accomplish this by using one ground plane. If you need to pinpoint a specific area, then I would buy a beam, mount it vertically, and use a rotor to point it at whatever highway you want to get your tx/rx as strong as possible.

73,
RT307

PS of all the GP's listed, I'd pick the Maco.
 
The DB said:
I ran a few models with the 4nec2 modeling software to see the radiation patterns for two end fed half wavelength antennas 5 meters high over "real ground" at various distances apart. They are also in phase. This is what I found...

1/2 wavelength apart...

1.jpg


5/8 wavelength apart...

2.jpg


3/4 wavelength apart...

3.jpg


7/8 wavelength apart...

4.jpg


1 wavelength apart...

5.jpg


At a half wavelength apart there are two lobes broadside to the pair of antennas. As you begin to spread the antennas apart from there the existing lobe begins to shrink as new lobes open in line with said antennas (on the X axis). These lobes continue to get larger, and if continued past the point shown here begins to split into two lobes each.

Because of this the distance of separation matters. If you are looking for two deep nulls 1/2 wavelength separation is your best bet. If you are looking for maximum gain in two directions 5/8 wavelength apart is your best bet, although a 3/4 wavelength separation will yield 0.06 dB less gain, this is insignificant and will not be noticed by anyone.

These look just like the diagrams shown in the last few versions of the ARRL Antenna Book for antennas with similar spacing apart. It was listed in said book to be for quarter wavelength antennas and these models are of half wavelength antennas. I guess size does not make much of a difference here.

Well there was my first modeling project... I learned a thing or two in the process and hope it is of help.


The DB
Click to expand...


I wanted to show the same thing but I am on my phone at work. Can't do much pattern work on it. :D. As for the length of tbe antennas, the patterns will remain the same as will the relative gain over a single antenna. In practice you just end up with a system with a little greater or less overall gain depending on the antennas used.
 
Maco V-5000
height will help you out alot
if you cant make the trip at 4 and 7 miles then something is wrong somewhere
keep in mind when the noise level goes up you wont ever have anything to cut thru it or even be able to hear them
but 1 antenna a metal antenna
and put it as high as you can
watch the powerlines
 
North Texas Mudduck said:
Maco V-5000
height will help you out alot
if you cant make the trip at 4 and 7 miles then something is wrong somewhere
keep in mind when the noise level goes up you wont ever have anything to cut thru it or even be able to hear them
but 1 antenna a metal antenna
and put it as high as you can
watch the powerlines
Click to expand...

the colons represent the e-ways the hypons are my road...
I May do better with an antenna switch...
Maco V5000 on each side of my ranch home
my house in the middle.
::.....::
::----::
::.....::
 
Last edited:
Captain Kilowatt said:
Question: What good would that do? Answer: Absolutely nothing at all. Both antennas are omnidirectional. All you gain is one antenna being 40-50 feet closer than the other.
Click to expand...

That was my question would an antenna switch
provide me anymore range on either e-way
Or would 40-50 ft. closer not be noticable????
 
No you wont be able to peg a guy needle with the antenna 50 foot closer
or even with the other antenna or 2 antennas

if you get the Maco V-5000 then put it as high as you can
50 foot would be a great start

1 antenna is all you will need
 
Would Mounting an Ol'' Moon Raker Vertically pointing straight up in the air
give me more range than a regular omni-directional antenna.
Or would I be better off with the Maco V-5000?

What effect would being vertical have on the moon-raker???
it may be good for skip.... rolling on floor laughing?
Anybody want to test this ideal???
 

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