research idea in rf circuit design

[carrier]

hi
anyone have a research idea in rf circuit design in M.S. level.
i have a ms in communication system and i'm interested in rf circuit design.
thanks

 

[Abdallah]

HELLO I AM Abdallah....15years old from egypt

please i aam very intersted in designing wirless remote by rf(radio frequancy) Iam a beginer in studding generally electronics i know the function of the well known electronic components...really i have no experiance or idea on designing the rf circutes......................................i hope we will be good friends and i hope you will explain to me makeing these circuits and their waveforms from a t o z.....................
specially after i have read that you are good and intrested in this way.......if you agree send me your msn email address and we can make chat by the messenger................

hoppyelectronics@hotmail.com

thanx

your young brother abdallah

 

[biff44]

Allright, here is one concept. Modern military aircraft achieve great agility by operating in the unstable region of flight. That is, if there were not some very fast control loops keeping the plane flying properly, the pilot would not be able to pilot it for more than a few seconds before it augered in.

In the old days, when vacuum tubes were precious, designers needed to find a way to get a complete radio receiver to work with only one or two tubes. They did so with regenerative receivers. These were basically unstable circuits that, just as they were about to self oscillate were deliberately quenched. By operating in the "almost" unstable region, a single tube was able to provide 80 dB of gain in a receiver, and bring Howdy Doody to millions of listeners!

So, what is the point? In today's world of mmic circuits and systems on a chip, every component in the circuit is carefully designed to always be stable under all conditions. Expensive shielding boxes are crafted to keep receivers from feeding back on themselves for fear of causing instability.

Is it possible to use deliberate instability to solve some modern problems? This, except for a few injection locked oscillator applications, is fertile unexplored ground. These are just some wild ideas that may not be feasible, but how about:
*improved RFID tag range
*broadband software defined radios that can withstand broadband noise and interference without high speed DSP processors/FFT filters
*simplified system on a chip by violating the stability creed

You could come up with an actual circuit, or develop the theory of how to use instability in a circuit or system for a nifty MS project.

(just remembered another recent example of thinking in the unstable way: regenerative frequency dividers for lower phase noise or millimeter waves applications.)