Damn, lots been said while I was at work today... Most has been addressed so I will talk about the more relevant parts to me.
I've been talking about this on the forum for years now, this thread is the first time I recall anyone else mentioning it... I should also add nomadradio's post from before these...
EDIT: Thinking back I have seen bob85 mention it a few times recently.
With the coax canceling abilities of my VNA's (yes, I have two), I have noticed the SWR and resonance on an antenna, at the feed point, is not necessarily the same point. Modeling has also shown this. However, they will always be be close to each other. An antenna with a wider SWR bandwidth will give more variance than an antenna with a narrower bandwidth when it comes to how close resonance is to SWR.
Peak gain, as measured by field strength, tends to be at a higher frequency then the low (V)SWR and resonant points of the antenna. This is something I see consistently. There are two things that I have found that affect how far away this peak field strength point can be...
- How narrow the (V)SWR bandwidth of the antenna is
- How much loss is in the feed line between the radio/amp and the antenna.
Both of these appear to push the peak gain of an antenna system towards the low SWR point. When it comes to feed line losses, by combining modeling and a feed line loss calculator (I like qst's) I can actually show this very thing happening when it comes to an antenna's efficiency/gain.
This is absolutely correct. I can give two examples, both based on real world testing and measurements, that show this happening. In one of the cases you increase the antenna's radiation resistance part of R, and in the other you lower the loss component of R, in both cases, this will increase the antennas field strength (or gain if it is done in modeling). That being said, like field strength, when I mention this most people don't seem to care, or even bother to try and understand, so I don't bring it up often...
The DB
