I want to convert dBm to watts/ sq meter, V/m & Amp/m. pl help.
dBm is dB re 1 milliwatt. If power output of something is p dbm, then it is 10^(p/10) milliwatts.
If you radiate that power from an antenna, you need to know the distance from the antenna and the directionality of the antenna to get field strength in W/m². At a distance R from an isotropic antenna (they don't really exist) radiating P watts, the field strength is P/(4pi*R²) watts per square meter. For real antennas, in the forward direction, multiply by antenna gain (recognize the gain comes from restricting the radiation to a narrow beam, to radiate more in one direction requires radiating less in all others)
We could probably help more with more specifics of what you are trying to do.