In Kwang Kim

Electrically Small, Millimeter Wave Dual Band Meta-Resonator Antennas

A meta-resonator antenna is one in which a metamaterial resonator is the radiating element of the antenna. In this paper, meta-resonator antennas are developed using multilayer low temperature co-fired ceramics techniques. A pair of split-ring resonators (SRR) is used as the radiating element of the antenna. The two SRRs have different resonance frequencies due to the opposite placement of the gaps and the antenna can operate at both frequencies. Other multiband antennas can be designed by adding different metamaterial resonators. No matching network is required since feeding is by inductive/capacitive coupling. The size of the meta-resonator antenna is 10% of a conventional microstrip antenna. The electrical size (ka) of the antenna is 0.386, the bandwidth is 2%, gain is 3.76 dB and efficiency is 71%. An omnidirectional meta-resonator antenna is designed by removing the ground plane and by using a microstrip line as the feed line. The feed line can also serve as a monopole antenna if desired. The radiation pattern, efficiency and gain of the omnidirectional meta-resonator antenna are similar to those of a monopole antenna.

Electric and magnetic resonances in symmetric pairs of split ring resonators

Orientation of the gap of a split ring resonator determines whether the resonance is an electric or magnetic response. When the gap of a split ring resonator is parallel to the incident E-field, an electric resonance is excited, and when the gap is perpendicular to the E-field, a magnetic resonance is excited. In this paper, we show that strong coupling between adjacent symmetric split ring resonators can give rise to dual electric and magnetic resonances if the intercell spacing is small enough. By varying the interparticle spacing within a unit cell, we can position the dual resonances as desired. Inverting the simulated reflection and transmission coefficients of a periodic slab of symmetric pairs of split ring resonators, the permittivity and permeability can be extracted and are shown to result in negative properties at resonance. Through a careful analysis of the extracted and Lorentz model fits of the permittivity and permeability, together with the simulated S-parameters, we have established a cle...

Embedded Wideband Metaresonator Antenna on a High-Impedance Ground Plane for Vehicular Applications

A conformal embedded wideband metaresonator antenna is proposed for military vehicular applications. Metamaterials are artificial materials that exhibit plasmonic resonances with subwavelength sizes of metallic structures. Metaresonator antennas use metamaterial structures as radiators to reduce the size of antennas and design multiband antennas. A small-dipole antenna is placed on a high-impedance ground plane with a conjoined split-ring resonator (SRR). The total volume of the antenna, including the effectively high impedance ground plane, is only 0.51λ0 × 0.41λ0 × 0.05 λ0. The embedded multilayer ceramic antenna was fabricated using a low-temperature co-fired ceramic (LTCC) technique and is well suited for embedment in the armor. Very good agreement was obtained between full-wave simulation results and measurements of the reflection coefficient and radiation pattern.

Fabrication of 3-D Metamaterials Using LTCC Techniques for High-Frequency Applications

Metamaterials are artificially engineered metallo-dielectric microstructures that display strong resonance behavior although their electrical size is . Individually they behave like LC oscillators and collectively they give rise to effective permittivity and permeability that are highly dispersive in the resonance region and may even become negative. In this paper, metamaterials with 3-D interconnects are designed for low-temperature co-fired ceramic (LTCC) fabrication. The fabricated materials are characterized experimentally using a free-space measurement system in the 33-110 GHz range. Dupont 951 is chosen as the substrate with silver ink for metallization. Three-layer and five-layer samples were fabricated. The fabricated samples exhibit electric resonance, magnetic resonance, or both, depending on the orientation and geometry of the metallic microstructure. The materials are passive and may be modeled using series and/or parallel LC circuits. LTCC metamaterials are proposed for packaging applications in microwave integrated circuits that may require embedded passive inductors, capacitors, resistor elements, and circuits that are functional at required frequencies and are inactive at other frequencies.

Flexible isotropic antenna using a split ring resonator on a thin film substrate

Isotropic antennas on thin Kapton films have been designed using a small dipole antenna and a split ring resonator (SRR) for 2.4 GHz applications. The size of the designed antenna is 0.24λ x 0.24λ and the electrical size (ka) is 0.75. The antenna has an isotropic radiation pattern and the maximum gain is 1.83dB. If the antenna is attached on a curved surface, the operating frequency increases as the radius of the surface decreases since the electrical length of the antenna decreases. When the radius of the surface is 0.04λ, the volume of the cylindrical antenna is 0.24λ x 0.08λ x 0.08λ and the radiation pattern is still isotropic.

Compact, multi band plasmonic resonator antenna

A dual band microstrip plasmonic resonator antenna has been designed using a SRR and a feed line that also functions as a monopole antenna. This is the new aspect of the antenna design. The feed line is placed adjacent to the SRR, so that there is sufficient coupling to excite the plasmonic resonance and at the same time the line can radiate as an independent monopole antenna. The antenna has two operating frequencies at 7.2 GHz and 10.4 GHz. 7.2 GHz is the same as that calculated for a monopole antenna of the same length and 10.4 GHz is same as the resonance frequency of the SRR. Thus, the monopole antenna and SRR radiate independently at their respective frequencies. Each operating frequency has a similar omnidirectional radiation pattern, maximum gain and radiation efficiency. We can design a multiband antenna by adding different size SRRs or by designing other geometries that have multiple plasmonic resonances. If the resonance frequencies are designed to be close, a wideband antenna also can be realized. The big advantage of this design is its simplicity. No matching network was required at the each operating frequency. This antenna can be applied to a multiband wireless communication system due to its small size and low fabrication cost. We are currently implementing the design and experimental data will be shown for comparison with the design data.

Microstrip patch antenna on LTCC metamaterial substrates in millimeter wave bands

There has been much research to improve the properties and to reduce the size of microstrip antennas and high permittivity dielectric substrates have been considered to reduce the size of microstrip antennas. High permeability materials are considered for the substrates of microstrip antennas instead of high permittivity materials. But, Pendry was the first to suggest the use of split ring resonators (SRRs) as a canonical metamaterial structure that gives rise to an effective magnetic response without the need for magnetic materials. When we design a microstrip antenna on the metamaterial substrate, which has SRR structures in the substrate, we can reduce the size of a microstrip patch antenna [8]. Additionally, if we use the SRRs that have various scales in the substrate, we can design the multi-band antenna [9]. The SRR is a ring with a gap. When the axis of the ring is parallel with the magnetic field, the strong induced current in the SRR results in a magnetic resonance whose frequency depends on the scale of the geometry. We can change the resonance frequency from low frequency to optical bands by changing the scale of the SRR. Metamaterial substrates for millimeter wave bands can also be designed by scaling the SRR structures. Millimeter wave systems have many advantages for military and commercial applications. They have better resolution than microwave systems because of the narrow beamwidth. This is proper for radar systems. In the commercial area, the demand on the EM frequency spectrum has suddenly increased with the rapid growth of wireless systems. However, the frequency spectrum is limited and microwave frequency bands are saturated, hence millimeter frequency bands can be a solution to provide more spectrum resources.

SRR-loaded small dipole antenna with electromagnetic bandgap ground plane

A metamaterial resonator loaded small dipole antenna placed above the electromagnetic bandgap (EBG) surface is proposed. Two split ring resonators (SRRs) are loaded to the dipole. The dipole antenna, the SRRs, and the EBG are integrated in one dielectric using Low Temperature Co-fired Ceramic (LTCC) technique. The simulation results demonstrate that, by loading the SRR structure, a low profile and very small dipole (less than 0.15λ in length) antenna over an EBG can have a broad bandwidth. A bandwidth of 10% at 1.93 GHz is achieved. The simulated gain is greater than 6.1 dB and efficiency is 90%. Few EBG cells used in the present design reduce the overall size of the antenna structure. The volume of the antenna including the EBG structure is 0.51λ×0.42λ×0.05λ.

Effect of capacitive coupling between split-ring resonators

There is much interest in metamaterials for the microwave and optical applications because their electromagnetic properties are vastly different from ordinary materials. The split ring resonator (SRR) is the canonical metamaterial structure that has a magnetic response without magnetic materials. Magnetic properties of the SRR are considered as the substrate of the microstrip patch antenna instead of high permittivity materials because we can, not only reduce the size of the patch, but also improve the bandwidth of the antenna using high permeability materials for substrates of microstrip patch antennas. We also can design multi-band antennas using various kinds of microstructure in substrates.

LTCC Metamaterial Substrates for Millimeter-Wave Applications

The LTCC (Low-temperature Cofired Ceramics) technique is considered for the metamaterial substrate of a microstrip antenna. The target frequency is 76 GHz~77 GHz for the automotive radar. The metamaterial substrate design and microstirp antenna design are discussed in this paper. The reflection and transmission coefficients of metamaterials are simulated using HFSS simulator. The permittivity and the permeability are calculated from these coefficients. The microstrip antennas are designed with this substrate. The characteristics of antenna on the metamaterial substrate are compared with those of the antennas on the dielectric substrate.