Interesting antenna tests

Well today I thought I'd try as a test.

On 10.1Mhz -

a) 1.5m homebrew "Miracle Whip" standalone indoors
b) A 25ft wire "picture rail" antenna.

As expected, the "picture rail" antenna got a lot more spots.

But the curious thing was that when I took a few callsigns that had been present
over the complete test period and looked at the average S/N ratio of each antenna
with them, the average gain was only 4db !

I'm puzzled by this, as this was not what I would expect.

I was expecting a lot more average gain, but then my sample of callsigns was small,
all about the same path length and direction. Even so, it's still a lot less than I was

Anyone else done similar tests / calculations ?

73 de Andy