Jong-Eon Park

FDTD analysis of resonant transmission in an electrically small circular aperture with a ridge

In this paper, we have examined the convergence of the transmitted power of an electrically small aperture to the transmission cross section 3lambda2/4pi of it for a case of a circular aperture with a ridge. This property can be applied for any electrically small aperture regardless of size or shape even though only one example of the circular aperture is shown. Although not shown here, the comparison of the field distributions on the aperture with and without the ridge shows that the aperture fields for the original circular aperture is mainly reactive, while those are radiating for the ridged aperture.

Comparison of transmission resonance phenomena through small coupling apertures between two kinds of transmission resonance structures

We deal with two kinds of transmission resonance structures whose transmission areas are the same to each other as 3λ2/4π. One is a ridged aperture structure and the other is the structure employing aperture - to - cavity - to - aperture system. We expect the two structures to be useful for various applications such as near-field optical probes, compact optical data storage, and nano-lithography.

Comparison of Mutual Coupling Phenomena in Subwavelength Ridged Circular Apertures and Half-Wavelength Dipole Antenna Arrays

The resonant microwave transmission characteristics of several coupled subwavelength ridged circular aperture arrangements in a thin metallic film are investigated using the three-dimensional finite-difference time-domain (3D FDTD) method. Simple equivalent circuits represented by the self and mutual conductances that have been quantitatively extracted for each resonance condition, including the mutual coupling effects, are also devised with the help of virtual magnetic current elements. Furthermore, a duality is identified between the ridged circular apertures and conventional half-wavelength dipole arrays based on comparing the respective resonance conditions.

Resonant transmission enhancement with a subwavelength aperture

We have considered the degree of enhancement in the transmitted power through the subwavelength aperture, which can be achieved by introducing some perturbation in small aperture shape. The maximum transmission condition has been described from the viewpoint of equivalent circuit representation. This study may find applications such as optical data storage and nanolithography as well as small aperture-type antenna design.

Aperture-body resonance(ABR) and transmission- cavity resonance(TCR) conditions in aperture coupling problems

The relationship between aperture-body resonance (ABR) and transmission-cavity resonance phenomena is discussed. From the viewpoints of both the equivalent circuit representation for transmission resonance condition and the funneling mechanism, the ABR and the TCR are essentially the same to each other. The common features of them are thought to be a general description for the transmission resonance phenomenon associated with aperture coupling problems. The ABR concept is extended to aperture coupling problems of various structures. Two types of transmission cavity, which can be used as the TCR structures, are also considered. Discussion is given on the role of the cavity in the aperture-coupled transmission cavity structures in the light of the TCR.

Analysis of resonant transmission characteristics of two sub-wavelength apertures with a ridge located in parallel

There have been numerous studies for the problem of electromagnetic coupling through electrically small holes or apertures in microwave areas and optics. Bethe was first treated this problem using the aperture polarizability concept and it was found that the transmittance normalized to the area scales as (a/λ)4 where a is the hole radius and λ is the wavelength [1]. This problem was generalized by Harrington introducing radiation terms in the equivalent circuit and he suggested an easy way of improving the poor transmittance by satisfying resonance condition [2]. The resonance condition can be realized by loading the small aperture with a capacitive lumped element or a capacitive structure. Recently, Yeo et. al. have analyzed an electrically small circular aperture with a ridge for resonant transmission and have shown the convergence of the transmitted power of an electrically small aperture to the transmission cross section [3].

Equivalent circuit-based analysis of a small resonant circular aperture

In the problems of electromagnetic coupling, the transmission of the electromagnetic wave through such a hole is typically very weak when the lateral dimensions of an aperture are smaller than half the wavelength. It is usually believed to scale as the fourth power of the aperture diameter for example for small circular aperture [1]. Recently a kind of ridged aperture [2] that provides a significant enhance of the transmission efficiency through the small aperture was proposed for applications of near-field optical areas such as optical data storage, nano-lithography, and nano-microscopy.

Resonant transmission of a class of sub-wavelength apertures in thin conducting screen

In this paper, we have examined the resonant transmission of a class of sub- wavelength apertures such as a ridged circular aperture and a narrow rectangular slot in thin infinite conducting screen. The transmitted power for varying the ridge gap and the slot length for these apertures, respectively, has been compared with the transmission cross section of the apertures to check out the relationship between them, and the admittance of the apertures have been computed to validate the resonant behavior of them. It turns out that the transmitted power of an electrically small aperture at a resonance converges to the transmission cross section of 3/4pi square wavelengths independent of its shape and size as long as the aperture size is sufficiently small compared to the wavelength.

Coupling similarities between ridged circular apertures and half wavelength dipoles

In this paper, we obtain transmission cross section (TCS) for the multiple resonant apertures using full wave simulation. The equivalent magnetic current element of the structure is put to explain the resonant transmission effectively. Finally we solve the self conductance and mutual conductances for four different structures. The conductances are quite similar to the resistances of multiple dipoles.

Analysis of electromagnetic environments in indoor offices using parallel FDTD method

Recently, as an information-oriented society we are living advances on ubiquitous society, most of IT devices such as mobile phones and laptop computers become wireless and small-sized, and the convergence among them is accelerated as the adaptation of new technologies becomes faster. Moreover, numerous IT-devices can be operated at the same time in a small space such as an office room. Due to this circumstance, possibilities of intentional and/or unintentional electromagnetic fields from these IT-devices affecting other home appliances and other IT-devices are highly increased. Therefore, demands for the accurate prediction methods of electromagnetic compatibility (EMC) and electromagnetic interference (EMI) between devices in an electromagnetic environment with multiple sources called a dense electromagnetic environment keep increasing [1].