Real time tip clearance measurement in gas turbines and other rotating machinery is an interesting way to provide enhanced reliability, cost effective maintenance and more overall safety. This paper presents a novel microwave sensor for blade tip clearance measurement in turbine engines. The sensor consists on a miniaturized PIFA antenna shielded by an outer protective shell. The special materials used enable the probe to operate in the presence of corrosive gases and temperature variations. The sensor was optimized through simulation, then manufactured and measured. Experimental results agree well with the simulated ones, showing that the sensor under study is capable of providing accurate and reliable data for the desired application.