The DB: They didn't read any real radio book on the subject, if they did they would have worded this very differently.
Which book? "The radio handbook" isn't very descriptive, and can refer to any number of books. Seriously though, what they would have read, if they read anything, would be an antenna book of some sort.
Agreed 100%
This is a warning sign. A low SWR is not necessarily a good thing, and a low SWR over a huge bandwidth is more often the sign of a problem than a good antenna.
Thank you
This isn't necessarily the case. If you get the spacing correct, the parasitic "reflector" element will generally add more forward gain, but the front to back ratio will be slightly worse. In other words, for key-downs this would be second to another very similar looking setup.
Thank you
That depends on how high the Antron 99 is. If it is mounted at ground level, sure, however if it is on a tower 30 feet off the ground and this setup outperforms it you need to figure out what is wrong with your Antron 99. It may seem like it outperforms it for a short distance, but the phrase "height is might" really does mean something when it comes to antennas, and really is far more important than anything else when it comes to performance.
12 feet, I am going to raise it higher before getting an antenna build going.
This isn't the only setup used in key downs, and is really more a sales pitch than anything.
A "cophased" antenna array generally refers to a 0 degree phased array, which is another way of saying that both antennas get the same signal at the same time. An end fire array like this is not a 0 degree phased array, one of the antennas gets the signal a little later than the other. The two setups will have very different results, including different directions for whatever gain they may have.
Thank you for explaining the difference !
Assuming these setups were done with the same type of phasing, setting these up would simply be adding more antennas in line with the same distance between them. If you master getting the first two working, adding more in is just following the same directions again.
Very very cool, I was hoping this was the case!
Here is a more complete and more readable version of the chart Captain Kilowatt posted above. It is larger than the forum will show so if you need it to be larger right click to see the whole thing.
Awesome, thank you once again!
The columns denote the antennas separation, so everything in the second column are two antennas 1/4 wavelength apart.
The rows are the phase differential between antennas. The first row, for example, are what people in the CB world like to call "cophasing" and the term is limited to this row. As you can see, their really isn't much gain to be had with cophasing, at least with the distances used on vehicles, however, if you can get the antennas further apart you can get some real gain from such a setup..
Good to know
The phasing commonly used for end fire arrays are in the third and fourth rows. Actually, the setups I have seen used in the CB world are row three, 90 degree separation, and the distance apart is about halfway between the first and second columns. This is used more for the easy setup than anything, their is more gain to be had with other setups, but getting the antenna system tuned really gets to be a pain, and you can't easily direct feed it without some form of matching, which is not desirable when used in key downs, which is where this type of setup is generally used.
If you want forward gain and rear rejection, and have enough area on the roof for this type of setup, this is one way of achieving it.
Excellent
If you really want help setting up such an antenna system, don't buy this, their is plenty of information available for free on-line.
The DB
I won't buy the e-book, thank you for all of your help explaining what is happening and how it is working, the image graphic is hi-resolution thank you very much!
-LeapFrog
