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Antenna Theory. Questions involving dual antennas!

8113 Northern MN

Active Member
Aug 9, 2013
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Virginia,MN
Back in my early days of CB use, I always ran with dual whips on the back of my jeep. I never understood the concept of wavelength and modulation and SWR. I simply hooked up the whips...connected them to the Jeep and turned the radio on!

Now that I understand having to tune in SWR, and how radio waves work (well in basics), Im wondering if there is a proper way to run dual antennas on a vehicle without causing problems and actually benefiting my RX and TX. Yesterday I purchased a mag mount for a 3ft Firestik I had laying around and hooked it up. I also had a K30 antenna which is what I have been using in the Radio for quite some time. Ive talked all over the country with the K30 and was interested how much better reception I would get with the Firestik. But first I wanted to play around. I bought a coupler that hooks both antennas into one and then into the radio. I put the K30 towards the front of the roof and the Firestick towards the back. I drive a 2007 Chevy Trailblazer so there is a bit of room up there. I checked the SWRs and they were just a hair above 1:1 so i felt comfortable and began trying. I was successfully able to make a contact with a station out of germany as well as many US contacts. Having never made a trip across the pond in my mobile I instantly wanted to believe it was because I was running dual antennas and I had hit the holy grail setup.

So whats the truth and facts about running dual antennas. Am I actually gaining anything from this setup? Am I loosing anything from it? As long as SWRs are watched and kept low is this a viable setup?


And next. If this works.....is it possible to run dual antennas to the home base. I have an Imax 2000 70' to the tip currently and also have a homemade dipole in the rafters of my shack. Both are perfectly tuned at 1:1. Would i see any gain in hooking both of them up at the same time?

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Oh Robb, you would make me do some major reading ;) Ive already got the sickness when it comes to "more power" and bigger and better Antennas. Im afraid if I get any crazier, my shack may become my bedroom because the wife is getting a bit irritated lol!
 
Oh Robb, you would make me do some major reading ;) Ive already got the sickness when it comes to "more power" and bigger and better Antennas. Im afraid if I get any crazier, my shack may become my bedroom because the wife is getting a bit irritated lol!
Maybe, but you should read it probably, lol. In one sentence you said you understood radio waves, and then in another sentence you wanted to hook a vertical and a horizontal antenna together.
 
I understand the BASICS....and the horizontal and vertical are separated by 50 ft or more....I know that I cant have them on the same pole running together...i get that. Im wondering about from a distance.
 
There is an entire section on phased arrays in the ARRL Antenna book dedicated to this topic, if you're interested. They even have models that show various signal patterns when using various types of phased arrays, complete with number of elements, spacing, and timing taken into consideration (all of which are important).

For CB use, a fairly accurate generalization is that it's usually not possible to obtain the spacing needed to accomplish much of anything with a phased array on a vehicle. There are some specific situations where it may be helpful, but generally it's a waste of time and money.

However, I encourage you to pick up the ARRL Antenna book and read up on this topic, if you're interested in it. There are some pretty need ways to direct your signal using phase arrays, and if you really are interested in doing this on the base, you can have a lot of fun.
 
Thanks alot Molecule. I believe I actually have a couple year old PDF version of the book you are talking about saved on my work computer. Perhaps I will need to take a browse through that section!

For me I just keep trying to think of ways to make bigger and better contacts ( in before "get your ticket and start operating HAM bands!). I really enjoy 11meter despite its ups and downs and bad seeds. The Imax has done me some wonders and ive literally talked all over the world on it. But the Dipole in the antenna has picked up some signals before that the Imax wasnt and that really surprised me. My longest contact with the dipole is with that good ole 135 Troublemaker out of Jamaica. I just would love to find a way to incorporate the receive ability of both at the same time. Or perhaps I just need to go the direction of getting a Beam lol
 
EASY - If dual antennas, for whatever band were of benefit and easy or fairly easy to install and tune believe me each and every Amateur in the world would use them exclusively on their vehicles.

ENUF SAID ??

Can you say HYPE from antenna companies in the C. B. HEYDAY
 
EASY - If dual antennas, for whatever band were of benefit and easy or fairly easy to install and tune believe me each and every Amateur in the world would use them exclusively on their vehicles.

ENUF SAID ??

Can you say HYPE from antenna companies in the C. B. HEYDAY
I wouldn't completely agree with that. A semi with a 53' box trailer certainly comes to mind here.
 
haha yea me and some locals were just talking about that on 38lsb. Relatively easy to set up mobile but no where near as easy when running big antennas on base station.

Hey a guy can wish right!
 
Maybe, but you should read it probably, lol. In one sentence you said you understood radio waves, and then in another sentence you wanted to hook a vertical and a horizontal antenna together.

What is wrong with that idea? It is done all the time but it has to be done right. Most FM broadcast stations run vertical and horizontal and a lot of amateur stations do on vhf/uhf TOO.
 
What is wrong with that idea? It is done all the time but it has to be done right. Most FM broadcast stations run vertical and horizontal and a lot of amateur stations do on vhf/uhf TOO.
An Imax2000 out back and a dipole in the attic on 11m? Are you serious?
 
With random length phase lines and random spacing who Knows what is happening on your mobile? you might be filling in some nulls in the pattern , but most likely you have actually reduced the efficiency of your ant.As stated earlier on most mobiles you can't get enough distance between the antennas to be of use and it is much more complicated than just buying a "coupler " and hooking them together. Sorry my friend but I think you have a lot of reading to do. Might be better to read up on parasitic elements and try converting that dipole to a beam. Yesterday I ran out of coffee so I had a cup of tee .Worked England for the first time in Months .Maybe I've found the holy grail for talking to the English
 
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