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This paper proposes a method for designing a new <em>ultra wide band</em> (UWB) multiple-input multiple-output (MIMO) antenna with two and four elements. First we presented an ultra-wide band antenna we studied these performances. Then, we studied the application of metamaterials to the design of MIMO antennas for miniaturization and the performance of antennas, in order to guarantee the proper functioning of the MIMO system with a much reduced separation distance between the radiating elements (λ/12), where the coupling can be very weak. The application of these circular double ring SRRs materials on the front plan of the antenna has contributed to the increasing of the antenna performance is studied in terms of S-Parameters, efficiency, diversity gain (DG), radiation properties and envelop correlation coefficient (ECC). It offers advantages such as the reduction of weight and congestion that is beneficial for their integration into satellite communications systems.

A novel optical rectenna design is presented in this paper to operate in S-band communication. We propose a new method of combining antennas and solar cells to collect and transmit optical and radio frequency signals respectively. In this work, we determined the electrical power collected, it can be used for the polarization of a diode or a low-noise amplifier in a receiver block thus simulation results provides a gain of 6.74 dBi at 2.9 GHz with an effective return loss of -33.62 dB and radiated power of 7.08 mW. These good results make it possible to use the antenna particularly in point-to-point communication systems. A three topologies of rectifying circuits are proposed in the present work. The parametric study has been shown that the efficiency RF/DC conversion can reach 66% for an input power of 10 dBm and a load resistance of 3 kΩ.

A new design of wideband microstrip antenna, where slots are placed on structure, is proposed. Also, a newly structure of a monopole antenna based on the noches form is designed using the HFSS. It has been found that the characteristics of new microstrip antenna are comparable to the conventional patch antennas, whereas its gain, directivity, and radiating efficiency are remarkably improved which make it to be useful in RFID chipless applications. The proposed antenna operates from 11.45 to 13.28 GHz, and 14.61 to 19.55 GHz can be used in RFID chipless applications, and it has a bandwidth about 677 MHz. The return loss of the proposed antenna is indeed below-10 dB. Prototype for all antennas are fabricated and measured and a good agreement between the measured and simulated results is achieved.