Radio Astronomy has made very significant contributions to human knowledge by discovering such exotic phenomena as quasars, pulsars, active galactic nuclei, superluminal motion and cosmic microwave background. These have been possible by the ever increasing sensitivity and angular resolution of the radio telescopes over the last six decades. Building large collecting area for antennas requires innovative technology to keep the costs down. A good example is the Giant Meter-wave Radio Telescope (GMRT) built near Pune in Western India. Similarly, increasing the resolution has required sophistication in radio interferometry and sensitive electronics and photonics. The next big push is the million square meter area radio telescope called the Square Kilometre Array (SKA), spread over hundreds to thousands of kms. operating over a very large frequency range of 70 MHz to 10 GHz for mid-SKA and 25 MHz for full SKA. This is being built by a global consortium of radio astronomers involving as many as 19 countries and is expected to be completed around 2020. In this tutorial, we will give the background and review the different designs of antennas that are being made as prototypes for SKA and the electronics that goes with them and summarize the current status of progress in radio astronomical techniques.