[TowerTalk] Quad vs. yagi

[Tom Rauch]

> Will a quad live through an ice storm? Will the yagi's do so any
> better? I can handle about 9 sq. ft with our winds up here, they
> sometimes gust as high as 70 mph. Very rare to get ice with any wind. 

Hi Mel,

Most of the benefits of quads are far over-rated. They do not, 
contrary to folklore, have "2 dB gain over a yagi".

A single loop has the maximum advantage over a dipole, and even 
that idea case favoring the quad almost always produces much 
less than the proclaimed "2 dB advantage". 

In actuality the gain of a full wave loop over a dipole can be 
anywhere from zero to two dB, depending on height and position. 
For example, contestors often use horizontal full-wave loops on 80 
meters  to "get gain" at high angles, when in reality there is no gain 
advantage over a dipole at low heights!

We can eliminate the hyperbole about gain, because it doesn't 
happen.

The "wave angle" thing is another exaggeration. A quad has 
essentially the same wave angle as a yagi of similar size mounted 
at the same boom height. No advantage there.

A quad can be quieter under conditions where the antenna is 
involved in "precipitation static", because it does not generally have 
the "pointed ends" sticking well out from the tower like a yagi. It is 
less subject to corona from the high impedance parts of the 
elements, where such corona does the most damage to receiving.

The advantages are slight to none in single band operation, that's 
why I never use quad antennas. You'll find most serious antenna 
guys fall in the category of "non-quad" users!

I can't speak for multiband quads, because I've never looked at 
them in depth, but it seems reasonable to assume if they have little 
or no advantage in monoband applications it won't get much better 
in multiband use.

If I were picking a "casual use" antenna, I would consider reliabilty 
and F/B ratio more than any other parameter. F/B ratio (and 
directivity) is what benefits receiving, NOT GAIN.  Gain is 
meaningless for HF receiving. I'd get a reliable antenna that has 
decent F/B ratio, and put it up as high and clear as is reasonable.

There will be plenty of advice on what antennas have decent 
reliability, good F/B and pattern, acceptable SWR bandwidth, and 
acceptable gain. That is about the order of importance for casual 
use.

I have no opinion of what antenna that would be, since I haven't 
used tribanders in many years. 
73, Tom W8JI
w8ji@contesting.com

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