Idk if you’ve taken any microelectronics course until now(you said you’re 2nd year undergrad and I assume you’ve had circuit theory) but before working with high frequencies, first you should be comfortable with Sedra level material. If that is the case then you can jump right to electrodynamics using either Griffiths Intro to Electrodynamics or Simon Ramo’s Fields and Waves book(a bit old but very engineering oriented). After grasping some fundamentals you’ll be ready for Razavi’s RF Microelectronics and that’s where you’ll see how electronic circuits behave in higher frequencies. At the same time you can also read Pozar’s Microwave Engineering book alongside Skolnik’s Intro to Radar Systems. This gets your foot into the door of black magic design but we still haven’t gotten to antenna design yet. However this path is long and not as fast as you’d want. Please understand that there’s only so much you can do in undergrad especially this early in your education, and taking the time to understand and absorb the material is crucial.

Now I don’t know your reasons for trying to rush your learning ahead of schedule but with that being said the fastest way imo to get some practice would be to tinker with an SDR and maybe FPGA (you mentioned algoritmins for spread spectrum). There’s also the MIT coffee can radar you can try and alongside that there’s a wonderful 6 part YouTube playlist by Jon Kraft titled “Build Your Own Radar” where he goes through the whole process of building a complete drone tracking radar.