So let me see if i understand ..you are a RF guy that want to do digital design .. Well vhdl and FPGAs are a little away for now. You should start by learning COMBINATORIAL and SEQUENTIAL digital design that will give you the basis to design digital circuitry .. Otherwise VHDL and all the FGA stuff don't make sense . Get a good book on DIGITAL design i think that if you are really commited in a month you can get a lot of insight .Once you know how to simplify combinatorial stuff ,create state machines ,counters ,then you could start practicing this stuff with a PAL or gal .. The reason is that this architectures require you to go to the lowest level .So one of these little chips is like having a DIGITAL lab .. you can design counters , addders , multiplexers etc . Go with a language like PALASM to programme those chips. is great to practice your digital design skills .The language is simple and close to the mathematical logical statements .. Only after that you can start learning a high level language like VERILOG or VHDL
Cheers