A compact triple band notched ultra-wideband (UWB) monopole antenna is presented in this paper. Split Ring Resonator (SRR) structure is exploited in various forms like Complementary Split Ring Resonator (CSRR), Split Ring Resonator Pair (SRRP) and CSRR on Electromagnetic Band Gap (EBG) structure to produce triple band notched characteristics in UWB spectrum. The proposed antenna produces triple band notched functions with integration of all three types of SRR on primary antenna. The parametric analysis of each form of SRR is presented along with their current distribution effects on triple band notched antenna. The proposed antenna prototype is fabricated and measured results are also compared with simulated one to understand the discrepancies. The measured and simulated results are presented to investigate the band notching characteristics of suggested antenna in terms of VSWR and radiation characteristics.

Future wireless communication needs antenna with multifunctional operation. This paper focuses on Terahertz Antenna that could be easily integrated with micro and nano devices. In this paper, an octagonal shaped Microstrip Fractal Antenna loaded with the EBG structure is designed for tri-band terahertz application. Triple band characteristic achieved by fractal radiating patch is loaded with Electronic Band Gap (EBG). The antenna is working on triple band characteristics at 948 GHz, 984GHz and, 1040 GHz with overall dimensions of 700x900 µm2. The result and performance show that the recommended antenna will be compatible with compact wireless devices and Monolithic Microwave Integrated Circuit (MMIC). All simulation work has been done using electromagnetic software Ansoft High Frequency Structure Simulator (HFSS) and CST studio suite. The electromagnetic features like S11 parameters, VSWR, gain, efficiency and the radiation characteristics of such antenna are also explored. The simulation results show that this antenna has 9 dB realized gain at 0.948 THz resonating frequency.

In this paper we have studied the characteristics of mushroom-like Electromagnetic Band Gap (EBG) structure and performance of a low profile antenna over it. Afterward, a novel EBG surface is presented by some modifications in mushroom-like EBG structure. This structure, which has more compact electrical dimensions, is analyzed and its electromagnetic properties are derived. Results show that resonant frequency of this novel structure is about 15.3% lower than the basic structure with the same size. Moreover, the novel EBG structure has been used as the ground plane of antenna. Its application has improved radiation of a low profile dipole antenna. The antenna performance over the new EBG ground plane is compared with the conventional mushroom-like EBG structure. Simulation results show that using this slot loaded EBG surface, results in 13.68dB improvement in antenna return loss, in comparison with conventional mushroom-like EBG, and 33.87dB improvement in comparison with metal ground plane. Besides, results show that, EBG ground planes have increased the input match frequency bandwidth of antenna.

Background and Objectives: Multi-input multi-output (MIMO) antennas have been of interest in wireless communications in recent years. In these systems, many antennas are placed next to each other. The most important issue in the design of MIMO antennas is mutual coupling. Many methods have been proposed to reduce the mutual coupling of MIMO antennas. Many of these methods require an additional substrate on top or bottom of the antenna. In the reduction of mutual couplings electromagnetic band-gap (EBG) structures are preferred because they are coplanar with the antenna and can be compactly designed. In this paper, to reduce mutual coupling in MIMO antennas, a novel compact EBG structure based on the genetic algorithm optimization is proposed.Methods: The method proposed in this paper to design an optimal EBG structure is to use a genetic algorithm (GA). In this method, an EBG unit cell is designed by a binary code, and then the 7×2 EBG structure of the unit cell is placed between two antenna elements with λ/2 distance. The optimization algorithm tries to find the best unit cell to reduce the mutual coupling between two elements. After 70 generations in the genetic algorithm, the GA determines a compact structure of EBG elements which reduces mutual coupling significantly.Results: Two-element patch antennas with and without the proposed EBG structure are fabricated and the mutual couplings between array elements are measured at 5.68GHz in both cases. It is shown that the proposed compact EBG structure reduced the isolation of the two antennas by 27 dB. This decrease in mutual coupling is much higher than in the previous papers. The proposed EBG has little effect on other antenna radiation parameters such as S11 and radiation patterns.Conclusion: In general, in this paper, a compact and coplanar EBG structure is proposed to significantly reduce the mutual coupling in MIMO antennas. The method presented in this paper can be used for other MIMO antenna configurations at other frequencies and the proposed method will create a completely optimal structure to reduce mutual coupling.