Just took a look at both 'Cubex's and 'Signal Engineering's web sites. Between the two of them, I think I come closer to believing 'Cubex's advertising than 'S.I's. What does that proove about their antennas? Nothing, just which one has better (more believable) advertising. (Didn't bother looking at prices cuz I certainly don't plan on buying from either one.)
All I have to go on as to the feeding systems are what I can see in the pictures and what's said on the web sites. So, that means a few 'assumptions' on my part. Keeping that in mind...
The 'S.I.' quad appears to be fed with a gamma or simular type matching system. Not really anything 'wrong' with that, but also not really anything particularly 'right' with it either. As long as the impedances are matched, and there isn't a huge amount of loss, it ought'a work fine. How about the horizontal/vertical feeds? Not real sure about that. If the electrical lengths of those matching devices is chosen carefully, the one not in use sort of disapears 'electrically'. As far as 'where' the driven element is fed, side, or bottom, that's the 'standard'/typical means of changing polarity with a quad. No problem with that, I can buy it.
Next!
I thend to put more 'faith' in what I read on 'Cubex's site, mostly. They seem to tend to 'ring' more 'bells' with what I'm familiar with in how they 'do' things. Can't say I agree with everything they say, but I can say I at least 'see' where they're comming from, sort of. Wouldn't go so far as to say their electrical characteristics for their antenna is 'correct', but they are an order of magnitude more so than 'S.I.'s! They are at least consistant.
I'm not a mechanical engineer by any means so couldn't say which is the stronger antenna 'mechanically'. That's a very big consideration when you're talking about any antenna like a quad, and weather.
Quads and yagi type antennas are only very roughly comparable. There are some differences, and when comparing comparative ease in erecting them, the yagi will usually come out ahead.
Electrically, a quad tends to 'open' and 'close' the bands. Probably won't be the loudest thing on the band when it's open though. Just depends on what you want, or your operating 'style'. If you live at a very high elevation, get the quad. If not, take your pick.
- 'Doc
More than you ever wanted to hear about antennas, and then I left a lot of stuff out too.
