In the far-field region, the range of WPT depends on one or more of the following parameters, namely, transmitter power, directive gain
of the transmitting and receiving antennas, and receiver sensitivity.
Design Of Microstrip Square-patch Antenna For Improved Bandwidth And Directive Gain
, International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 2(2): 441-444.
Under the condition that the array is relatively accurately calibrated, Optimum Directive Gain
(ODG) method in  gets the optimum gain.
Taking a parameter called sensitivity factor as constraints on array efficiency and robustness against array uncertainty, the proposed method could obtain a good tradeoff between directive gain
, array efficiency and robustness against array uncertainty.
of an antenna in a particular direction is defined as ratio of power density in that direction at a given distance to the power density that would be radiated at the same distance by an isotropic antenna radiating the same total power Maximum Directive gain
is defined as directivity of antenna
Three design charts present (1) free-space propagation loss as a function of frequency and distance; (2) the aperture gain of an antenna from 1.0 to 40 GHz; and (3) the directive gain
of an antenna with various combinations of azimuth and elevation beamwidth.
Antenna with low-profile and high directive gain
has been widely researched, and the demand in practical applications is increasing [1, 2].
This use of phase shifters would also result in an increased antenna directive gain
. However, obtaining extra directive gain
could be at the expense of insertion losses introduced by phase shifters that would decrease the overall antenna gain.
In both of the H and E planes, the directive gain
of the antenna with FSS has been improved about 3.5 dB in the broadside near theta = 0[degrees] ([equivalent to] the opposite direction of the FSS position (-z-axis)), compared to the simple antenna with semi-monopole-like patterns.
TABLE I ELEMENT GAINS Horn Near Stripline Center Center Element Element Frequency (GHz) 5.00 5.00 Directive gain
(dB) 1.68 1.68 Passive reflective coefficient 0.63 0.15 Calculated gain (dB) -0.54 1.67 Measured gain (dB) -0.05 1.80 Element Gain
These are beamwidth BW and first sidelobe level SLL of the E-plane and H-plane radiation patterns, fundamental resonance frequency [f.sub.101] in GHz, antenna directive gain
G in dB, radiation aperture efficiency [eta] = 4[pi][S.sub.a]/[[lambda].sup.2.sub.0], in %, where [S.sub.a] is the antenna aperture surface, DC to RF efficiency in %, EIRP in W, and SSB spectral density in dBc/Hz.
For a given incident wave power, the power available from the equivalent generator is the same for all antennas having the same directive gain
. A convenient way of specifying the power in the incoming wave is the power available in an isotropic antenna.