Table 2. Major specifications of the different antennas
PRINCIPLE	UNLOADED PIFA 60 mm LONG	TOP LOADED WITH A CAPACITOR	INDUCTOR LOADED NEAR FEED POINT
Center frequency (min. |S11|)	1.20 GHz, sim. 1.07 GHz, meas.	1.22 GHz, sim. 0.99 GHz, meas.	1.20 GHz, sim. 1.08 GHz, meas.
Loading value		1.1 pF	18 nH
PIFA element lenght	60 mm	40 mm	40 mm
Efficiency, within BW where S11>–6 dB, meas.	>55%	>65%	>65%
Size ground plane	40 mm × 100 mm	40 mm × 100 mm	40 mm × 100 mm
BW S11>–6 dB	7.3% (78 MHz), meas. 9% (150 MHz), sim.	÷, meas. 9% (110 MHz), sim.	6.7% (71 MHz), meas. 3.9 % (45 MHz), sim.
Radiation Pattern	Omnidirectional	Omnidirectional	Omnidirectional
Maximum gain	3.9 dBi	2.1 dBi	3.3 dBi
Size or center frequency reduction, as compared to the unloaded 40-mm-long PIFA		32%, sim. 39%, meas.	33%, sim. 34%, meas.