Why We are measuring power at RF frequencies ?

[tarakapraveen]

Hi

Why we are measuring power at RF frequencies rather than voltage or current?
please give me the answer?

Thanking you in advance

Regards ,
goud

 

[xxargs]

Hi

Why we are measuring power at RF frequencies rather than voltage or current?
please give me the answer?

Thanking you in advance

Regards ,
goud

all intresting information transported via power - energy in small part of joule,Ws per bit etc.

different transporting media have differet impedances and if you notate only in volt or ampere you must always also have information of used impedance in measure point and also phase relation between voltage and current in case of complex impedance.

Using power, gain, attenuate is 'black boxing' of internal structure of all different types of impedances in signalprocessing in system and you not need care this in system thinking - but if notate in voltage/current - you must know every step inside and know impedance and loss on measure point and how long to next impedans shift etc.

RF-ransistors output have around 3 Ohm complex impedance or lower and using quarter wave transformer to make 50 Ohm not so complex output - if you using voltage probe, you measure different voltage on different place around quarter wave transformer and you cannot calculate power if you not know impedance, voltage, current and phase angle between current and voltage in every specific measure point for same power level. its easier to measure output of resulting power to ports impedance matched power meter (to avoid power reflection)...

and in last ends - power carriers information is only intresting for end user - not if power delevery in high voltage and low current or high current and low voltage, this can always transformed to right voltage/current (=impedance) relation to fit reciver power detectors range.