GWR LEVEL TRANSMITTER

It's all to do with the time-of-flight of the signal. Think about it.

Already thot abt it but not getting the anwers , I think thats why this forum exists .

If someone knows how exactly this happens then please help.

I read but mostly it seems to be related to the way microwave travels.

The di-electric constant relates in this case to the electrical losses ocurring in the "guidance" of the wave. The wave is guided physically, most probably along a metallic guide, so there are electrical losses to the signal, both on it's way down and then up.

Therefore, it makes sense to describe that distance along which the signal is most reliable/ where the detected signal strength has the best resolution for accurate conversion to an actual level measurement.

Quite.

To arrive at a destination, one must follow a sequence of signposts.

There are two simple reasons.

1) You have trouble measuring minimum transit time which sets nearest point from electronics (transmitter/receiver). Transmitted and received pulses can't be resolved.

2) Signal loses strength over transmission line due to losses in the surrounding dielectric including air and after some distance it becomes within the noise limit and can not be detected with confidence. This sets the maximum detectable distance from electronics (transmitter/receiver).

Are you satisfied?

Ok, but what about transition zone on lower end?

I am still not ver clear about it, could you please elaborate.

msn:

"Ok, but what about transition zone on lower end?"

Are you asking why there is no reflection from the end of the sensor rod?

End of the sensor rod is sure to reflect back if there is anything reaches there and the same will return and follow the attenuation in the path as well.

Normally for high dielectric medium like water, signal travels to the end of the rod easily, but for low dielectric medium near to air signal gets lots of spread and is lost on the way. In such cases, we use a coaxial guide to limit the spread within the co-axial tube and this extends the signal up to the end of the tube like the way you can transmit signal in co-axial cables and you get reflection only from end which can be hundreds of meters.

Think that you have a 1GHz cellular transmitter so how much length of antenna you need to radio the signal in air and lose it? Just a small whip antenna works well for you. However, nothing great happens to the signal in the co-axial cable connected to the whip antenna.

If GHz signal could travel on open power lines then no one will ever waste money on co-axial cables and there will not be anything called Radio Transmitter.