Thanks for the info.
I got these terms from a job ad.
Beware of HR Department waffle!
Why is it called Gain Flatness?
Have a look at the first graph which I have knocked-up. (UK meaning, not USA meaning!)
How do you know what output voltage is 1db lower than the input? is there a simple formula for this?
No formulae that I know of.
You have to make some plots of input and output power and look at the graphs.
So, look at my second graph.
Return loss is a measure of impedance matching of the inputs and outputs?
Sort of.
This is a big subject which can be confusing.
Let us try some simple generalisations.
In RF work, inputs and outputs of "equipment" is specified to have a certain impedance, usually 50 Ohms.
Connecting cables, usually coax, and their connectors have a characteristic impedance. Again usually 50 Ohms.
(Note, you CANNOT measure that 50 Ohms with a multimeter !).
When a perfect system is connected with perfect cables, all the energy which comes out of a source is absorbed in the load at the far end of the cable.
When the load is not perfect, some of the energy is reflected back from the load to the source.
These reflections give rise to standing waves in the connecting cable. Hence we get the expression VSWR (Voltage Standing Wave Ratio).
If we were to measure the voltage at points along the cable from the source to the load we would see that the voltage varies. The ratio of the maximum and minimum voltages is the VSWR.
The VSWR depends on the characteristics of the load (and the connecting cable, but lets just keep is simple).
So, one way of specifying how well a "load" is matched to the ideal 50 Ohms would be to specify its VSWR.
A better way is to specify its "Return Loss", how much of the incident power from the source is reflected back.
The return loss is usually measured in dB.
A Return Loss of 10dB would mean that one tenth of the incident power is reflected. Not a very good match.
A Return Loss of 20dB would mean that one hundredth of the incident power is reflected. A reasonable match for most common applications.
A Return Loss of 30dB would mean that one thousandth of the incident power is reflected. Good for all but the most demanding applications.
Yes how do you measure the Return loss? using a network analyzer?
Return Loss can be measured using a "Return Loss Bridge" - Google it.
I dont know of it will show up in Google, but a company I worked for many years ago made a bit of kit called a Rho-Tector" which was basically an RLB adapter for use with existing signal generators and power meters.
As for the network analyser, I suggest that you Google it.
My brain is aching a bit now, I hope that this helps.
JimB