Analysis of the specific absorption rate in handset antennas with slotted ground planes

The study of the interaction between human head and handset antennas should be taken into account since all the mobile phones have to guarantee a biological compatibility. This research analyzes several antennas with different slotted ground planes in terms of free space and also in terms of human head interaction. The main objective is to compare the measured bandwidth and efficiency in free space and the impact on measured SAR (Specific Absorption Rate) of such antennas as a function of the slot configuration and the antenna/slot location. Results show that slots may be useful to increase bandwidth and efficiency while keeping a similar SAR compared to the non-slotted ground plane. Changing the antenna and the slot location is a good way to achieve a significant SAR reduction.Peer ReviewedPostprint (published version

Diseño de una antena multibanda con ranuras en el plano de masa: una técnica para facilitar la integración de la línea de alimentación

The integration of transmission lines is a difficult task due to the presence of slots. In order to facilitate the integration of the feeding transmission line which connects the antenna with the RF-module, this research proposes a ground plane modification using central slots. Numerical simulation using MoM is used to understand the effect of the slots on the ground plane and several prototypes have been built to validate the present technique. Through this technique is possible to obtain a multiband antenna while keeping the same antenna geometry, small volume and simplifying the PCB (Printed Circuit Board) design.Peer ReviewedPostprint (published version

A Metamaterial-Based Handset Antenna with the SAR Reduction

A method to reduce the specific absorption rate(SAR) of the antenna for WiMAX mobile communication is proposed in this paper. The SAR reduction is achieved by miniaturizing the physical size of the antenna for the given resonance frequency by devising a metamaterial-composite right- and left-handed(CRLH) configuration-based radiator much smaller than the quarter-guided wavelength adopted a lot in the conventional planar inverted F antenna(PIFA) or modified monopole antenna. The proposed antenna is placed near the head-phantom and its SAR is evaluated by the full-wave simulations(SEMCAD X), where the metamaterial-inspired antenna is shown to have the lower value than a modified monopole as the reference in terms of the SAR.TRU

An Orthogonally Polarized Negative Resonance CRLH Patch Antenna

A novel fully-printed microstrip antenna with negative first resonance and dual polarization is proposed. The radiator is printed on the 1-layer substrate instead of multilayers. The -1st resonance results from a composite right- and left-handed(CRLH) structure that has a circumferentially interlocked gap capacitively coupling a patch with a shorted-ring. This compact antenna is provided with a dual-polarization capability by creating two orthogonal linear polarizations in one body with coaxial feeds. The design is carried out by doing full-wave EM field simulation which is compared with the measurement of the fabricated antenna prototype. The measured results give the gain of 5 dBi and the efficiency of 78% at the -1st resonance mode as the center frequency of a downlink channel of the bandwidth over 20 MHz with 29 dB polarization isolation for mobile communication. © The Korean Institute of Electrical Engineers.TRU

RF Channel-Selectivity Sensing by a Small Antenna of Metamaterial Channel Filters for 5G Sub-6-GHz Bands

In this paper, a new small antenna is suggested for 5G Sub-6-GHz band mobile communication. It can change the channel among the three given bands (called the 3.5-GHz area), as a wide-band antenna is connected to a small multiplexer comprising three metamaterial channel filters. The function of channel selection of this antenna system is experimentally demonstrated to prove the validity of the presented scheme. The channel selection for 5G mobile communication is conducted from f1 (channel 1) through f2 (channel 2) to f3 (channel 3), when TX and RX antennas with gains over 0 dBi and S11 less than −10 dB are located far-field apart (RFar ≫ 2.1 cm), and result in the transmission coefficient (S21) being the greatest at the selected channel, which is detected by a vector network analyzer

Channel Selectivity of Satellite Transponders with the Antenna Combined with a Size-Reduced Metallic Waveguide Bandpass Filter Having Thin Metamaterial Resonators

Global and intercontinental networking relies on satellite communication. Its wireless communication system always has antennas and their feed assembly comprising waveguides. This makes the satellite payload heavy and costly. In this paper, a novel method is proposed to effectively reduce the size of a waveguide bandpass filter (BPF). Because the metallic cavities make the conventional waveguide end up with a large geometry, especially for high-order BPFs, very compact waveguide-type resonators having metamaterial zeroth-order resonance (WG-ZOR) are designed on the cross-section of the waveguide and substituted for the cavities. While the cavities are half-wavelength resonators, the WG-ZOR is shorter than one eighth of a wavelength. A substantial reduction in size and weight of the waveguide filter is observed as the resonators are cascaded in series through coupling elements in the X-band much longer than K- or Ka-band. An X-band of 7.25~7.75 GHz is chosen to verify the method as the passband with attenuation of 40 dB at 7.00 GHz and 8.00 GHz as the roll-off in the stopband. The BPF is manufactured using the CNC milling technique. The design is carried out with geometrical parameters, not of the level of 10 μm, but the level of 100 μm, which is good for manufacturers but a big challenge for component designers. The measurement of the manufactured metal waveguide filter reveals that the passband has about ≤1 dB and ≤−15 dB as insertion loss and reflection coefficient and the stopband has ≤−40 dB as attenuation, which are in good agreement with the results of the circuit and simulation. The proposed filter has a length of 3.5 λg as the eighth-order BPF, but the conventional waveguide is 5 λg as the seventh-order BPF for the same area of the cross-section. This metamaterial BPF is combined with a horn antenna. The filter enables the wide-band antenna to distinguish the band of transmission from that of noise suppression. This channel selectivity is obviously observed by the filter integrated antenna test