[Lowfer] A field strength question

[Andy - KU4XR]

Gentlemen: 
I would appreciate anyones answer to this question regarding measuring
field strength. Hobbyist operators are allowed a maximum permissible radiation of;2400/Freq.(KHz) microvolts/Meter as measured at 300 meters from the xmit antenna,while operating in the 160 to 190 KHz range. 
*** Question : what does the /meter -( per meter ) refer to ?? In the recesses of my memory, I keep thinking it to refer to the size of the antenna on the receiving/measuring device. I've searched the net in
vain trying to get a clear answer, even the FCC website, but can't seem to be sure that this is the correct assumption. I have a genuine interest in knowing this technical way to determine signal output. This is of course the way the FCC would measure the output of a signal they monitored. I am fully aware of the 1 watt input/50 foot height issue, so please don't bother going there. If you can answer my question, and would be kind enough to share your knowledge with me; I will appreciate it.
Thanks; and 73 to all: Andy - KU4XR