Patch antennas are popular for their well-known attractive features, such as low profile, light weight, and compatibility with MMICs. Their main disadvantage is an intrinsic limitation in bandwidth, which is due to the resonant nature of the patch structure.
Modern communication systems (GPS, vehicular, WLAN, etc.) however, often require compact, low-cost antennas, thus rendering planar technology useful and sometimes unavoidable.
The EM-coupled patch has a greater impedance bandwidth than a conventional single-layer patch antenna