# Some Basic Principles of RF Electronic Systems and Antennas

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## Abstract

Basic principles that apply to all electronic systems and to antennas in particular include: (1) Only signal plus noise can be measured, not signal by itself; (2) signals add coherently whereas noise adds incoherently; (3) signal-to-noise ratio (SNR) gain at the receiver is only accomplished by voltage integration; (4) radio performance goes as one over the square-root of the SNR. The keys to understanding the SNR in a receiver are Friis’ Link Margin Equation and Friis’ formula for the noise factor. These relationships are explained because they should be well-understood by electronic systems engineers.

## Keywords

Electronically scanned array Fourier transform Conservation of energy Signal to noise ratio (SNR) Electromagnetic reciprocity Coherent integration Friis Link margin equation Noise figure Noise factor## Copyright information

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