We investigate the benefits of mutual coupling effects between the passive elements of intelligent reconfigurable surfaces (IRSs) on maximizing the achievable rate of downlink Internet-of-Things (IoT) networks. In this paper, we present an electromagnetic (EM) coupling model for IRSs whose elements are connected minimum scattering antennas (i.e., dipoles). Using Chu's theory, we incorporate the finite antenna size constraint on each element of the IRS to obtain the IRS mutual impedance matrix. By maximizing the IRS phase shiters using the gradient ascent procedure, our numerical results show that mutual coupling is indeed crucial to avoid the achievable rate degradation when the spacing between IRS elements is down to a fraction of the wavelength.

翻译：我们研究智能可重新配置表面的被动元素之间的相互连接效应对最大限度地扩大可实现的下链接互联网(IoT)网络的可实现速度的好处。在本文中,我们为元素连接最小散射天线(即dipoles)的IRS提供了一种电磁(EM)混合模型。根据Chu的理论,我们把对IRS每个元素的有限天线尺寸限制纳入IRS中,以获得IRS相互阻塞矩阵。通过利用梯度作为程序最大限度地增加IRS级拉链器,我们的数字结果显示,当IRS元素之间的间距降至波长的一小部分时,相互连接对于避免可实现的速率退化确实至关重要。