Hi Ogulcan,
greetings from Australia, welcome to the forum :)
radio astronomy a wonderful subject. I wonder if you have heard whistlers with your VLF receiver ? ~ 15kHz was the frequency, I used a very large multi-turn coil of cable, something I used to enjoy when I lived out in the country away from big towns and cities with all their radio noise. The main problem was the 60Hz hum from the mains electric power supplies.
A good time to consider getting deeper into radio astronomy with the next solar max on the way (even if its going to be a smaller than usual one). Just about any receiver from ~ 20 MHz to 50MHz is good for receiving Solar Flares. I regularly would hear the flares on our 50MHz amateur radio band.
Jupiter is a good source of radio noise ... the 18 - 22MHz seems to be around the peak tho it does spread a bit more than that.
Those are a couple of examples that can be done with a basic and relatively cheap home system.
To get signals from deep space, say pulsars, requires a more substantial investment in dish antenna low noise receiver, technical knowledge etc etc, not for the beginner, but something to aim for as you grow in your experience :)
do some searching on google ... there's masses of info, look in your local library ( if you haven't already) and keep coming back to PF and tell us all about your experiments and post your questions and see if any of us can help you out :)
this site has some good info...
http://www.radiosky.com/
Dave
