## Antenna - Theory .com: The Antenna Site

antenna-theory.com :: View topic - Questions about using spectrum analyzer in measurement
antenna-theory.com
Antenna Theory

Author Message
masonlee
Antenna-Theory.com Newbie

Joined: 11 Feb 2012
Posts: 3

 Posted: Wed Feb 15, 2012 12:29 pm    Post subject: Questions about using spectrum analyzer in measurement Hi, When we use spectrum analyzer to measure antenna receive power for gain calculation, i find out that the spectrum analyzer can measure few kind of powers like channel power, average power and total power. So which kind of power should i choose? During the measurement with the spectrum analyzer, is it a must to see a peak in the receive power vs frequency plot? I found out that it still showing some power value even the screen does not show a peak. How much the frequency span i should set? Thanks
wolberine
Antenna Theory Regular

Joined: 01 Mar 2011
Posts: 35

 Posted: Thu Feb 16, 2012 1:53 pm    Post subject: What are you specifically trying to measure? Can you provide screen shots if possible?
masonlee
Antenna-Theory.com Newbie

Joined: 11 Feb 2012
Posts: 3

 Posted: Thu Feb 16, 2012 4:08 pm    Post subject: I trying to measure the radiation pattern and gain of an antenna. Just like the antenna measurement tutorial in this forum. I connect a spectrum analyzer to the antenna under test and measure the receive power. When measuring the radiation pattern, at certain angle, the screen of the spectrum analyzer just showing a noise floor signal (without a peak) with low power level, can this low power be record? Is it accurate?
bigSteve
Antenna Wizard

Joined: 14 Mar 2009
Posts: 265

 Posted: Fri Feb 17, 2012 2:22 am    Post subject: Antenna Gain on the Spectrum Analyzer Antenna gain is a function of frequency. So the first thing to know is that when someone says the gain of an antenna is 3 dB, this means the gain at a certain frequency. The gain of a single antenna will generally be different at separate frequencies. So the appropriate settings will depend on what you are using as an input. Remember that gain is basically the ratio of power received to power transmitted (factoring in the pathless). So if you want to measure the gain of an antenna at f=1 GHz, then typically you are sending a broad pulse of power and you want to know the energy at 1 GHz. So you may integrate over a frequency span around 1 GHz to get the power there. Basically, you want the parameters you are using to determine the input power and output power (on your spectrum analyzer) to match. It doesn't matter exactly what you choose as long as you are consistent.
masonlee
Antenna-Theory.com Newbie

Joined: 11 Feb 2012
Posts: 3

 Posted: Fri Feb 17, 2012 2:55 pm    Post subject: Re: Antenna Gain on the Spectrum Analyzer From the data sheet of the spectrum analyzer, i found that it allow us to switch on/off a preamp. So what is the function of this preamp?
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First
 All times are GMT Page 1 of 1

 Jump to: Select a forum The Antenna Forum----------------Questions Related to Antenna TheoryNews
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum