# What is LNB noise figure?

## What is LNB noise figure?

The noise figure of the LNB is a measurement of how sensitive the LNB is or how much noise the LNB will add to the signal you may be intending to receive. The lower the noise figure of the LNB the better the LNB will be able to receive weaker signals.

### What should be the LNB frequency?

A Universal LNB has a switchable local oscillator frequency of 9.75/10.60 GHz to provide two modes of operation: low band reception (10.70–11.70 GHz) and high band reception (11.70–12.75 GHz).

#### Does LNB affect signal strength?

The more noise an LNB adds, the worse the signal strength becomes. Signal quality is typically measured as a carrier-to-noise ratio (CNR, C/No or C/N ratio) – and modems require a minimum C/N ratio to acquire a signal.

**What is the minimum noise for an LNA amplifier?**

It must operate between 50Ω terminations. As described in the MAX2656 data sheet, the optimum bias resistance (RBIAS) for minimum noise figure is 715Ω.

**Which is better higher or lower noise figures?**

that’s not universally true. there are applications where noises are desired. in those cases, higher noise figures are helpful. in most applications, you want to process a signal, not the noise so a lower noise figure is better.

## Why is the SNR always higher than the noise?

The SNR of the input is always higher than the output as the gain of both input signal and noise is the same plus added noise of the amplifier. So a low noise factor adds as little noise as possible to get as close to ratio=1 as possible. Noise Figure is the 10*log version of the linear Noise Factor.

### What is the noise factor for one dB loss?

Expressed in dB, the NF is equal to -S21 (dB). Something with one dB loss has one dB noise figure. See our page on cascade analysis. The noise factor contributions of each stage in a chain follow this equation: This is known as the Friis equation, after Harald Friis.