Following on from the discussion about the effect of rain on my 9-el 2M antenna - where mention was made about VSWR bandwidth - I remembered that the SWR curves I showed were at the end of 25m of RG-213. As we all know this would make the SWR curve look better than the curve obtained if measured at the antenna terminals. I thought it might be interesting to see what it might actually be at the antenna. Prompted by Owen (VK2OMD) I downloaded the latest version of AntScope for my AA-1400 and took a graph of my, still rain-soaked, antenna...
...entering parameters for 25m of RG-213 and getting AntScope to subtract the effect of the cable loss...
... which shows that the antenna has actually a much narrower VSWR bandwidth than seen at the end of the 25m cable run - indicating a fairly high Q antenna.
This gave me an idea - what if I added 25m of RG-174 to the 25m run of RG-213 ? Sure enough this fixes the problem...
...for all those who suffer from poor SWR this may be a solution to all your woes...
I am going to hook up a rain-detector to a pair of coaxial relay changeovers which switches in the RG-174 when it precipitates...
And again...
