Transmission-Line Networks Cloaking Objects From Electromagnetic Fields

Abstract

We consider a novel method of cloaking objects from the surrounding electromagnetic fields in the microwave region. The method is based on transmission-line networks that simulate the wave propagation in the medium surrounding the cloaked object. The electromagnetic fields from the surrounding medium are coupled into the transmission-line network that guides the waves through the cloak thus leaving the cloaked object undetected. The cloaked object can be an array or interconnected mesh of small inclusions that fit inside the transmission-line network.

Impedance-Matched Microwave Lens

“…In [9] the dispersion and impedance were studied for threedimensional unloaded and loaded networks, but in this letter we choose to use an unloaded two-dimensional network, for simplicity of consideration and design. The dispersion relation of such a network is [11] …”

“…Using the simple parallel-plate approximation, as was done in [6,11], we have found that the suitable width and separation of the TLs are 1.266 mm and 3 mm, respectively [6].…”

“…To couple waves from free space to the network and vice versa, we have introduced short sections of gradually enlarging transmission lines, as proposed in [11]. These lines of the "transition layer" have the length of 30 mm and the ratio between the width and height equal to the TLs in the network.…”

Inhomogeneous Microwave Lens Based on Periodically Loaded Transmission Lines

“…That design, which is based on two-dimensional or three-dimensional transmission-line (TL) networks, has the benefit of having very good impedance matching with free space as well as being fairly easy to manufacture. Independent control of both refractive index and wave impedance becomes possible without any magnetic insertions, simply using appropriate bulk periodical loads in the transmission lines and by tuning the impedance of the host transmission lines themselves [10][11][12]. A similar design was also used for realizing a Luneburg lens antenna in [13].…”

Ideally Hard Struts to Achieve Invisibility

“…Obviously, all these contributions make use of one or another approach. Some of them are working (cloaking the object) only for one polarization, others work with the size of the object to hide [6] or even on the type of materials the object can be made of, for instance only dielectrics with a given permittivity as in [7]. Other more recently interesting and published works are [8,9].…”