can any one suggest me some free ebooks or tutorials for VHF communication and HF communications with basics of communication pls... Thanks in advance

 

Hello,

In the handbooks that HAM radio amatuers use you will fild a lot of information.
There is the amereican from the ARRL:
http://www.box73.de/catalog/product_info.php?cPath=33_35_48&products_id=2081

And the english one from the RSGB:
http://www.box73.de/catalog/product_info.php?cPath=33_35_48&products_id=2155

See the attachements for the subjects discussed in the books.

Bertus

 

Thanks dude

 

It also helps to understand the fundamental analogy of a radio system. You should be able to search block diagrams similar to the one below:

http://ece.wpi.edu/books/EM_RF_lab/figures/figs01.pdf

That RF block diagram (first figure, first page) is generic in terms of modern radios, although I recommend you research the older analog based circuits first.

Any terms you aren't familiar with you should research, that may include "mixer".