IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331,Volume 6, Issue 3 (May. - Jun. 2013), PP 77-81 www.iosrjournals.org www.iosrjournals.org 77 | Page Effect of Scattering Parameters On MIMO System Capacity M. Tausif Afzal Rana1, M. Arif Khan2 , Waseem Afzal3,M. Zeeshan Baig3 and Danish Akhtar1 1Electrical Engineering, ISRA University, Islamabad Campus, 44000, Pakistan 2School of Computing and Mathematics, Charles Sturt University, Wagga 2650, Australia 3Electronic Engineering, Mohammad Ali Jinnah University, Islamabad, 44000, Pakistan Abstract: In this paper, the influence of scattering parameters on MIMO system capacity are discussed by de- signing MIMO antennas. In principle, the capacity of MIMO system can be increased by installing a high num- ber of antennas both at the transmitter and receiver. However, scattering parameters also play a vital role in the capacity of MIMO system. This behavior of capacity is observed in case of partially and fully correlated environment in the presence of scattering parameters. Keywords: MIMO, Capacity, Scattering Matrix, Antenna Array and Ansoft HFSS. I. Introduction In order to fulfil the requirement of growing technology, high data rate play a key role in wireless commu- nication. The most promising of such a technology is Multiple Input Multiple Output, (MIMO) base antenna systems. MIMO system consist of wireless channels with multiple antennas both at the transmitter and receiver. The pioneer work of[1] [2] give the basic concept of MIMO antennas. By installing a high number of antennas at the transmitter and receiver, the capacity of MIMO would be enhanced compared with conventional commu- nication systems such as single input single output (SISO), single input multiple output (SIMO), and Multiple input single output (MISO) [3] [4]. However, by increasing multiple antennas the signal correlation affects the channel capacity in partially and fully correlated environment[5]. In this paper,we examine the capacity of MIMO in the correlated environment by using scattering parame- ters. MIMO systems are very smart techniques in improving the capacity of wireless communication in the rich multipath atmosphere [6]. We obtained the scattering parameter matrix via Ansoft HFSS based antenna simula- tion. In fact, we only consider the case of 2 2  MIMO to explain in detail the effect of scattering parameters on the capacity of MIMO in correlated environment. We focused our analysis of capacity for partially and fully correlation situation. The capacity of MIMO based antenna systems givesa reasonable increase in capacity by installing a high number of antennas at the transmitter and receiver side. However, this method introduces not only signal correlation [7], but envelope correlation as well [8]. Reflection and transmission coefficient of scat- tering parameters are attained by designing microstrip patch antenna. The desired results to analyze the antenna performance are acquired by using a probe feed mechanism in patch antenna design. The plots of MIMO for two transmit and receive antenna are examined. We exploited scattering matrix with the help of scattering parameters of reflection and transmission using suggested design. Consequently, the effects of partially and fully correlated MIMO system on capacity by using scattering matrix are stud- ied.Comparative analysis of the percentage decrease of capacity in the presence of scattering matrix is also ob- served in Figure 5. The value against these Plots are shown in Table I. A detailed analysis proposed antenna and the expression of capacity in term of scattering parameters is presented in the next sections. Evaluation of MIMO Antennas The performance analysis of antenna such as Gain and Return Loss can be used to predict the behavior of MIMO based antenna array design. In [9], the author discuss that, correlation between the signals is a good measure to analyze a behavior of MIMO antenna system. The expression, which gives the correlation of complex signals, is referred as signal correlation [9]-[14]. The equation which gives the correlation co-efficient in case of MIMO antennas is dependent on the scattering parameters of reflection and transmission co-efficient which give birth to scattering matrix. This scattering matrix in term of correlation co-efficient ρ can be expressed as [13][14].