## What is load pull simulation?

Load-pull is the colloquial term applied to the process of systematically varying the impedance presented to a device under test (DUT), most often a transistor, to assess its performance and the associated conditions to deliver that performance in a network.

### What is load pull analysis?

Load pull analysis is used to map a set of contours (typically on a Smith Chart), which determine the maximum power output that can be achieved with a given load. These contours are very useful in calculating the actual impedance a device should see when it is being used.

#### What is source pull?

Source pull is the same as load pull except that the source impedance is changed instead of the load imped- ance. Load and source pull is used to measure a DUT in actual operating conditions. This method is important for large- signal, nonlinear devices where the operating point may change with power level or tuning.

What is a Smith chart used for?

The Smith chart is a graphical tool for determination of the reflection coefficient and impedance along a transmission line. It is an integral part of microwave circuit performance visualization, modern computer-aided design (CAD) tools, and RF/microwave test instrumentation.

What is load pull in RF?

A: Load pull is a technique for measuring performance parameters of an RF device and seeing how these vary with changes in matching impedance. The goal is to find the optimum operating point for an impedance match, working with the Smith chart.

## What is VSWR formula?

VSWR = (ZL + ZO + ZO – ZL)/(ZL + ZO – ZO + ZL) = ZO/ZL. We noted above that VSWR is a specification given in ratio form relative to 1, as an example 1.5:1. There are two special cases of VSWR, ∞:1 and 1:1. A ratio of infinity to one occurs when the load is an open circuit.

### What is VSWR vs SWR?

VSWR Definition It is a measure of how efficiently RF power is transmitted from the power source, through a transmission line, and into the load. A common example is a power amplifier connected to an antenna through a transmission line. SWR is, thus, the ratio between transmitted and reflected waves.

#### 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.

How is SWR calculated in load?

For the case of resistive loads (see sidebar), the SWR can be easily calculated as equal to the (Load R)/Z0 or Z0/(Load R), whichever gives a result greater than or equal to 1.0. The load or terminating resistance is the RF resistance of whatever is on the end of the transmission line.

What does VSWR 1.5 1 mean?

A VSWR of less than 1.5:1 is ideal, a VSWR of 2:1 is considered to be marginally acceptable in low power applications where power loss is more critical, although a VSWR as high as 6:1 may still be usable with the right equipment.