Measure rf signals on oscilloscope

[hatela]

Hii all,
I am doing a summer rf project on cellphone booster, specifically a 850Mhz/1900Mhz bidirectional amplifier.
I am new to rf, just started self learning it. I have an oscilloscope 15Mhz BK precision 1477, I wanted to ask if it would be any use in measuring when I build a prototype board.

Thanks

 

[disisku_22]

Hi,
This Oscilloscope for ur project is very less use, but u can use this to measure DC values and also u can make use to measure RF power by means of external RF detector. build ur own RF detector by using simple Schottky diode and connect this ckt to o/p of ur amplifier to measure DC voltage equivalent of RF power.

regards
roshni

 

[martine1212]

You need a scope whose BW is greater that the frequency of the signal you are measuring (assuming a simple sine wave).
So if you want to see 800-900 MHz signal in time domain you will need a scope with 1GHz of more BW.
The detector approach will not give you much information except that the signal is there with some XX amplitude/power.
And the diode approach works better with signal levels lower than about -20dBm.

 

[karesz]

Its so, he has a simple small bandwidth scope_I think in reality no chance to organize a higher bandwidth type, and 1 GHz so & so not.
I know otherwise, that good scopes (i.e. Tek & LeCroy, maybe HP too) have a linear roll-off of 6dB/octave, what means if you have to test a 900MHz signal & the trigger is in function usually so 2-40% over nominal bandwidth: relative sure is that you can apply a 500 MHz scope for a 900MHz signal, but I know=its a poormans solution, & possible will the scope not trigger.
In all case is the amplitude good predictable and to see...
For 1.8GHz clearly is only a detector to use_or some expensive scope...
Alternative can be in my opinion, a spectrum analyzer, but their are in 1.8GHz version not in all home labors too... :-(
Other important question is for me: where is the test signal from?
K.