Finding an antenna's "sweet spot"

[freema22]

I am embarrassed to be asking this question, because I feel like I should know the answer. I have a variety of antennas in my closet that I purchased at one time or another for various experiments and projects. These are antennas used for transmitting, primarily on 2m and 70cm ham bands. However, I'd be interested to know how efficient they are at receiving on other bands. I have a NANOVNA and can analyze them, but if I look at something like the SWR, that is for transmission efficiency. Is there another type of analysis that I can do that will give me an idea where their receiving "sweet spot" is?

Thanks,
Mike

 

[nd5y]

Receiving and transmitting gain/loss are the same. If the VNA shows the antenna is good for transmitting at a certain frequency then it will be just as good for receiving. That doesn't tell you if the antenna is really any good. You need to know what the radiation pattern is like. You probably can't mearure that yourself but depending on the type of antenna you can probably model it with software.

Another thing is making field strength measurements. Field strength meters are relatively easy to build and good for comparing similar antennas. You might be able to do that in reverse with a VNA if you can use it like a spectrum analyzer, put different antennas on it, and measure signal strength from a source transmitter.

 

[chief21]

Is there another type of analysis that I can do that will give me an idea where their receiving "sweet spot" is?

Not familiar with the NANOVNA, but most of the RigExpert analyzers will do an SWR chart/sweep function. You enter a range of frequencies and the analyzer will create a chart showing the SWR at various points within the range. Does the NANOVNA have that capability?

 

[sonm10]

Return-loss, but I think maybe another way of putting SWR.

 

[mmckenna]

Does the NANOVNA have that capability?

Yes, on an itty bitty screen…..

 

[ladn]

Yes, on an itty bitty screen…..

There's a PC app (and I think for Android as well) that links to the NANOVNA. Makes the screen data far easier to see.