Novel Desings Of Double Negative Metamaterial Antennas

Nowadays,the cellular industries require the antenna system capable of performing over the whole band of application without adding external system to control the shift;of the resonant,with the lowest cost of fabrication and with better electrical characteristics such as gain and efficiency are very important.For this reason,the effectiveness of microstrip patch antenna comes with easy to fabrication and has a low cost comparing with other antennas for the same purpose.Metamaterials are artificial material structures with a negative dielectric constant(?)and a permeability(?),which mean leading to a negative index of refraction.We use metamaterial to make a new tool to control and interact the electromagnetic waves when electromagnetic wave travels in this material.Because these unusual properties the metamaterial can be change the electric and magnetic property of electromagnetic wave going through it,and when the metamaterial is used in the fabrication of microwave elements and antennas the necessary properties can be enhanced.Also,miniaturization in the size of the element is possible as the structural cell size of metamaterial is less than one-fourth of the guided wavelength.In this thesis,novel double negative metamaterial antennas have been designed,focused on enhancing the performance of microstrip patch antenna like gain,directivity and return loss by adding metamaterial in front of patch antenna.The negative property received by creating unit cell structure.We can say the unit cell metamaterials circuit is combination circuits from series capacitors and inductors respectively.Wire lead to negative permittivity and microstrip gap direct to negative permeability.And this negative permittivity and permeability which leads to negative refractive index exhibits unusual properties compared to easily available materials in nature.This method is applied on microstrip patch antennas with regular metamaterial shapes like ring,wire,etc.The gain and bandwidth of microstrip patch antenna is improved at different frequency by creating different shapes of metamaterials.We start with simple shapes of metamaterial like omega and U-shape,and end with novel combination shape of C and U,C and C-opposite and new design.With different metamaterial design shapes the performance is increased in terms of gain,return loss,radiation pattern and directivity with the range operating at 28 GHz to work in 5G band.