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...

In this article, a novel monopole antenna which consists of a radiating patch with two modified L‐shaped notches to achieve broad bandwidth is presented for various mobile communication services such as wireless broadband, wireless local area network, digital mobile broadcasting, and ultrawideband (UWB) applications. The proposed antenna is designed to operate over 2–11.2 GHz for S11 < −10 dB. Details of the proposed antenna design approach and measured results are also presented and discussed. The novel monopole antenna has wide band impedance bandwidth, compact size, and low fabrication cost, which are suitable for communication services and UWB application. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1856–1860, 2013

In this article, we propose a compact cpw‐fed ultra‐wideband (UWB) antenna with dual band‐notched characteristics. The dual band‐notched are achieved by using two stepped impedance resonators. The measured results show that the proposed antenna has an impedance bandwidth from 2.97 to 10.7 GHz (113%), defined by VSWR<2, with two notched bands, covering all the WiMAX (3.3–3.6 GHz), WLAN (5.2–5.8 GHz), the antenna has a small size (20 × 20 × 1.6 mm3), and almost stable omnidirectional radiation pattern. The proposed antenna is designed, simulated, fabricated, and tested, and the measured results are in good agreement with the simulations. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:464–467, 2016

The performance of a broadband circularly polarized crossed-dipole antenna for long-term evolution services is presented in this study. The antenna consists of a pair of trapezoidal-shape dipoles, four trapezoidal parasitic elements, and a pair of three-quarter printed rings that generate a 90 phase difference between the dipoles. The axial ratio (AR) bandwidth is extended using two principal factors in this article. The first one is using trapezoidal parasitic elements, and the second one is employing the feed network in the sequentially rotated technique. Its 2 Â 2 array with a sequential-phase feeding network is introduced to achieve a noticeable improvement on the proposed dipole antenna performance. The measured results approve that the impedance and AR bandwidths of the proposed crosseddipole antenna are 44% (1.95-3.05 GHz) for S 11 < À10 dB and 31% (2.2-3 GHz) for AR ≤ 3 dB, respectively. Furthermore, by applying a 2 Â 2 array structure for the proposed antenna, the impedance, and AR bandwidths increased by 63% and 31%, respectively. Indeed, using trapezoidal parasitic elements adjacent to the dipole arms leads to generating further surface currents and causes to extend the impedance. A sequential-phase feeding network is in charge of extending the AR bandwidth of the antenna simultaneously.