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field strength antenna
- Thread starter bob85
- Start date
It sort of depends on exactly what you are testing and why.
For instance;
Just want a 'reference' reading to see how your signal is doing today? Any sized antenna would work, but it would always have to be the same for each time you did a check, today, tomorrow, next week.
Want repeatable and 'standardized' numbers for determining how 'much' signal is radiated by some antenna? How about a 1 meter antenna at a known distance. You would have all the information necessary for computing the E/I of the signal received at X distance through a 'standard' length of conductor. 'Course, that would depend on your' knowing what the inputed signal was to start with, and the characteristics of all devices/appliances/feed lines/etc/etc. between the transmitter and the point where the antenna ends.
The 'bad' part is that you have to know all of that stuff to get any kind of meaningful reading, which would provide some 'meaningful' numbers for making comparisons. ... ... Or! Do like the rest of us (mostly), do like 'M.C.' said, use a 'standard' sized antenna at the frequency in use, get the readings, then let the 'other' guy do the math. Much easier! What if the 'other' guy makes a wrong calculation or assumption? Hey! That's his problem, not yours! - LOL
- 'Doc
For instance;
Just want a 'reference' reading to see how your signal is doing today? Any sized antenna would work, but it would always have to be the same for each time you did a check, today, tomorrow, next week.
Want repeatable and 'standardized' numbers for determining how 'much' signal is radiated by some antenna? How about a 1 meter antenna at a known distance. You would have all the information necessary for computing the E/I of the signal received at X distance through a 'standard' length of conductor. 'Course, that would depend on your' knowing what the inputed signal was to start with, and the characteristics of all devices/appliances/feed lines/etc/etc. between the transmitter and the point where the antenna ends.
The 'bad' part is that you have to know all of that stuff to get any kind of meaningful reading, which would provide some 'meaningful' numbers for making comparisons. ... ... Or! Do like the rest of us (mostly), do like 'M.C.' said, use a 'standard' sized antenna at the frequency in use, get the readings, then let the 'other' guy do the math. Much easier! What if the 'other' guy makes a wrong calculation or assumption? Hey! That's his problem, not yours! - LOL
- 'Doc
I would think you would want something that is away from resonance to the frequency under test, but will still yeald a response from the test equitment. You don't want a neighbor affecting your signal responses.
I use a random length of coax that is terminated in a short. I make a loosely spaced coil of about 6' for 11 meters and that seems to work OK. I tape the coil to a 10' wooden dowel with about 20' - 30' of additional feed line. Then I just move this around the antenna looking for a response to start.
I have never seen this setup respond to far field transmitted radio signals. I use it only in the near field anyway, because my meter is just not responsive enough to get out very far. I am just looking for a signal response that crowds about 75% of maximum on the scale. That way I can see signals that are more and less than the start signal. Sometimes I do have to start over and reset the antenna and create a new start point when improving signals begin to all max-out on the meter.
I use a random length of coax that is terminated in a short. I make a loosely spaced coil of about 6' for 11 meters and that seems to work OK. I tape the coil to a 10' wooden dowel with about 20' - 30' of additional feed line. Then I just move this around the antenna looking for a response to start.
I have never seen this setup respond to far field transmitted radio signals. I use it only in the near field anyway, because my meter is just not responsive enough to get out very far. I am just looking for a signal response that crowds about 75% of maximum on the scale. That way I can see signals that are more and less than the start signal. Sometimes I do have to start over and reset the antenna and create a new start point when improving signals begin to all max-out on the meter.