## RF Design Guide

### Introduction

A communication link budget is a way of accounting for all gains and losses in a communication system from transmitter output power to the power seen by the receiver. By knowing all the losses and gain in our communication system, we can predict how reliably the signal can be received. For example, in a satellite communication link the provider would need to know the satellite transmitter power output, the gain provided by the transmit antenna, propagation loss etc. in order that the receiver can still receive the signal under adequate signal to noise ratio. Link budgets are useful in point to point communication where the link can be optimised with the use of highly directional transmitting and receiving antennas. The chart below shows a graphical representation of a link budget.

### Parameters

A basic link budget that allows calculation of received power can consist of the following parameters:

PTx: Transmit power
LTx: Losses at transmitter, cable, connectors etc.
GTx: Transmitter antenna gain.
LP: Propagation loss
LRx: Losses at receiver, cable, connectors etc.
$$P_{Rx} = P_{Tx}- L_{Tx}+G_{Tx}-L_{P}+G_{Rx}-L_{Rx}$$