 # Quick Answer: Is S21 Gained?

## What does S parameter mean?

Definition of S-parameters.

S-parameters describe the response of an N-port network to signal(s) incident to any or all of the ports.

Thus S21 means the response at port 2 due to a signal at port 1.

The most common “N-port” networks in microwaves are one-port and two-port networks..

## Why do we need S parameter?

S-parameters measure traveling waves rather than total voltages and currents. … S-parameters are analytically convenient; they allow for calculations of system performance by cascading the individual components. Flow-graph analysis can be used, which simplifies the analysis of a microwave system.

## What does S21 mean?

An S-parameter indicates the amount of power leaving one port of the network, given power entering another (or the same) port of the network. In the case of S21, the suffix “21” denotes the power leaving port 2, with power delivered to port 1. Note that in the RF world, S-parameters are measured using a 50Ω system.

## What is S21 measurement?

So S21 is a measure of the signal coming out port 2 relative to the RF stimulus entering port 1. When the numbers are the same (e.g., S11), in indicates a reflection measurement, as the input and output ports are the same.

## What is S11 S12 S21 S22?

S11 is the input port voltage reflection coefficient. S12 is the reverse voltage gain. S21 is the forward voltage gain. S22 is the output port voltage reflection coefficient. The S-parameter matrix can be used to determine reflection coefficients and transmission gains from both sides of a two port network.

## Is S11 return loss?

In practice, the most commonly quoted parameter in regards to antennas is S11. S11 represents how much power is reflected from the antenna, and hence is known as the reflection coefficient (sometimes written as gamma: or return loss. … This accepted power is either radiated or absorbed as losses within the antenna.

## Why VSWR is less than 2?

The range of values for VSWR is from 1 to ∞ . A VSWR value under 2 is considered suitable for most antenna applications. The antenna can be described as having a “Good Match”. So when someone says that the antenna is poorly matched, very often it means that the VSWR value exceeds 2 for a frequency of interest.

## How is gain flatness measured?

Gain flatness indicates the variation of an amplifier’s gain characteristic over the full frequency response range at a given temperature expressed in ±dB. The value is obtained by taking the difference between maximum and minimum gain, and dividing it by 2.

## Why return loss should be less than 10 db?

S11 is return loss of device, this parameter measures how much input power given to device is reflected back at input port. … S11 below -10dB means at least 90% input power is delivered to device and reflected power is less than 10%. This value is sufficient for many applications.

## Why is S matrix used in MW analysis?

S matrix is used in MW analysis to overcome the problems which occurs when H,Y,&Z parameters are used in high frequencies. Equipment is not readily available to measure total voltage &total current at the ports of the network. Short and open circuits are difficult to achieve over a broad band of frequencies.

## Are S parameters voltage or power?

S parameters in linear units always refer to the amplitude (voltage or current), while S parameters in logarithmic (dB) units always refer to power.

## How is S11 calculated?

S11 = b1/a1 for a2= 0 or Zl=Zo. This is an input reflection coefficient. S11 is equal to the ratio of a reflected wave and an incident wave with Zl=Zo. Thus, S11 can be plotted on a Smith chart and the input impedance of the two-port device can be found immediately.

## What is S11 in antenna?

S11 is a parameter of how well the power you put into an antenna stays there and doesn’t reflect back into you radio. With “stays there” one includes the amount of power radiated out into the air, as well as losses of the energy inside the antenna.