near the influential materials if the proximity effect is either an advantage or a disadvantage for an antenna system, depending on the size of an element materials, and small antenna is a small example ceramic chip antenna encapsulated in a cubic millimeters, using ESA and PSA as well. When designing a chip ceramic ESA, the dimensions of the mobile terminal device, the space for mounting the antenna, the space to be occupied by the antenna, and the antenna size [11].
FUNDAMENTAL LIMITATIONSmall antennas to reduce its size, gain and antenna efficiency degrade, and bandwidth tends to be narrower. Body limiting small antenna could have effective aperture as high as 98% of a half-wave dipole antenna when the antenna is optimally adapted to the load. There seems to be no limitation in reducing the size of the antennas, so did the antenna can be perfectly adequate. Perfect matching is impossible when an antenna is extremely low [12].Furthermore, the losses existing in the antenna structure and the corresponding circuit does not exceed the radiation resistance, which reduces the effective apertures that the efficiency of radiotherapy. With regard to the impedance of the antenna, the increase and decrease in the reactive component of the resistive elements results in a high Q factor and bandwidth will be reduced as a result. Reducing the size of the antenna and also makes them Q and bandwidth [13].The parameters affecting the fundamental limitations of small antennas are antenna Q (quality factor) of the bandwidth ratio g, the antenna size ka, where a is the radius of a sphere surrounding and antenna [14].ka is much smaller than unity. Q is proportion to ka ð Þ -3 .RBW is proportion to ka ð Þ 3 , RBW nearly equalsg is proportion ka ð Þ 4 .
CONCLUSIONIn a number of applications such as wireless Personal Computer Memory Card International Association cards, ESA's have been implemented that have adequate impedance bandwidth, and they are well matched. Some case matching the impedance bandwidth would decrease or in some case increase. Such that main fundamental limitation on antennas size versus impedance bandwidth brigs order to what can appear to be mysterious changes in antenna performance [15][16][17]. It should be noted that a small antenna, that is, appropriately designed to satisfy the system requirements should not be near certain materials so that designed antenna performance is substantially harmed. It can be said generally that the smaller the antenna becomes, the large the influence of such nearby materials is likely to be.
ACKNOWLEDGMENTThe authors would like to thank the management of CHARU-SAT and management of Chandubhai S Patel Institute of Technology for their continuous support and encouragement. ABSTRACT: In this letter, we present a compact dual-band dielectric resonator antenna for multi-input multi-output antenna is designed and fabricated. The proposed antenna consists of a single cylindrical dielectric resonator antenna (CDRA) excited from two orthogonal ports. The electromagnetic analysis is perfor...