This paper describes a compact and efficient rectenna based on a dual-diode microstrip rectifier at 2.45 GHz. This circuit has been designed and optimized using a global analysis technique which associates electromagnetic and circuit approaches. Due to the differential topology of the rectifier, neither input low-pass filter nor via-hole connections are needed. This makes the structure more compact reducing losses. Measurements of a single rectenna element show 83% efficiency over an optimal load of 1050 Ω at a power density of 0.31 mW/cm2. To increase the received RF power and then increase dc power over the load, identical rectennas have been interconnected to form arrays. Two and four elements rectenna arrays, connected either in parallel or in series, have been developed. It was shown that by properly choosing the interconnection topology and the optimal output load, higher dc voltage or dc power have been obtained. The four-element series-connected array can provide experimentally up to 3.85 times output dc voltage compared to the single rectenna. The parallel-connected rectenna arrays generate approximately 2.15 and 3.75 times output dc power for two and four elements, respectively.