Portable XY-Scanner

I would like to present you a new portable XY-scanner, suitable for microwave measuring. This device is Lidia del Moral’s Bachelor Thesis. Really, a great job.

Microwave Fresnel Lens Manufacturing.

This is my first research video. Now we are working on microwave lens. In this case, the lens is made up plastic, with a 3D printer, which draws cylinders with the radio and the height that we desire. You can see how we manufacure the lens, how we measure it in our anechoic chamber and the final result. We can improve this design, but that will be  the next chapter.




Un poco de optimismo por Emilio Duró.

Este es el primer “post” de este rincón. I am sorry I could not find english video of this topic.

Empiezo por mi último descubrimiento. Vale la pena ver algún video o entrevista de este tío, Emilio Duró y coger un poco de energía e ilusión para el día a día. Os señalo dos videos amodo de resumen, pero las ideas principales están aquí…


Total Reflection and optical fibers

What happens when an EM wave impinges from a dielectric medium on a planar interface with air? The EM wave bends its propagation direction. The angle forms between the surface normal and the propagation direction is bigger in the air than in the dielectric medium (Snell’s Law). Increasing the incidence angle in the dielectric, it be achieved an angle of propagation in the air equal to 90º. In this case, the incidence angle is called “critical angle”. For incidence angles bigger than the critical angle, total reflection can be achieve, that is, no energy flows from the dielectric to the air. That can be seen clearly in these experiment, where the light (a EM wave, of course) goes from water to air, forming different incidence angles.

This total reflection is a key element to understand optical fibers: the light can be “catched” because the angle of incidence from the dielectic medium is bigger than the critical angle.

15/4 Wavelength Transformer

A wavelength/4 transformer -or (2n+1) wavelength/4 –  is a classical circuit scheme which allow us to match a real impedance to a transmission line (TL). The transformer impedance is the geometric average of the real impedance and the TL impedance. What happens inside the transformer? In the transitory state, an imping wave flows to the transformer. Part of the energy flows to the load, and part goes back to the generator, that is a backward wave does exist inside the TL (t=6s). The wave inside the transformer arrives the load and part of it returns to the TL (t=14s). During this time, a quasi-standing wave is made in the TL. But at t=24s, the backward wave from the load “compensates” the reflection from the transformer, and a flowing wave is formed in the TL, that is, in the steady state, all the energy that comes from the generator goes to the transformer, and it will be consumed in the load.