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Recently, very small radio wave sensors (RWS) are tried to be put in to a human body for human health case purpose. As for a very small antenna in a sensor, normal-mode helical antenna (NMHA) is suitable due to its high efficiency with very small sizes. In this paper, antenna design method and electrical characteristics are clarified for very small NMHA which size is from 0.03 to 0.06 wavelengths...
5G, the next generation of wireless communications, is focusing on modern antenna technologies like massive MIMO, phased arrays and mm-wave band to obtain data rates up to 10 Gbps. In this paper, we have proposed a new 64 element, 8×8 phased series fed patch antenna array, for 28 GHz, mm-wave band 5G mobile base station antennas. The phased array steers its beam along the horizontal axis to provide...
Normal-Mode Helical Antenna (NMHA) is one of the promising antennas for implanted applications. Due to antennas put inside human body, electromagnetic simulations are needed to model human body and clarify electrical characteristics of antennas. In this paper, electromagnetic performances of NMHA were successfully clarified in human muscle condition by using Method of Moment (MoM) and Finite Element...
This paper presents the findings of a steerable higher order mode (TE$^{\mathrm {y}}_{1\delta 3}$ ) dielectric resonator antenna with parasitic elements. The beam steering was successfully achieved by switching the termination capacitor on the parasitic element. In this light, all of the dielectric resonator antennas (DRAs) have the same dielectric permittivity similar to that of ten and excited...
Density tapered array has a feature of having uniform excitations in all array elements. Then, a feeding network becomes very simple and array antenna will be applied for multi frequency operations. In this paper, a MATLAB program of achieving arbitrary density tapered distributions is developed. For example, the density distribution of cosine on a pedestal is designed. Moreover, radiation patterns...
In implantable antenna applications for human health care, normal-mode helical antenna (NMHA) is considered to be one of promising candidates. Due to antennas put inside human body, electromagnetic simulations are needed to model human body and clarify electrical characteristics of antennas. Electromagnetic performances of NMHA can be conveniently calculated by using Method of Moment (MoM). However,...
In the case of antennas applications for radio communication system, special antenna radiation patterns such as low side lobes and unsymmetrical side lobes are requested. In mobile communication systems, unsymmetrical side lobes are achieved at base station array antennas. There, based on a radiation pattern synthesis method, excitation coefficients of array elements are designed. In this lecture,...
Normal-Mode Helical Antenna (NMHA) is a promising candidate for medical implantable application due to its ability to achieve high efficiency in very small size, when self-resonant structure of the antenna is achieved. In use of NMHA for implantable application, a human body phantom is employed in antenna development stage. In the case of measurement of NMHA placed in a phantom, antenna setting and...
In mobile base station antennas, linear array antennas are employed to achieve shaped beams in the vertical plane. Also, antennas are designed to achieve multi-frequency use. In the case of expanding multi-frequency range, conventional equal element spacing configuration shows a defect of producing grating lobes. In order to suppress grating lobes, unequal element spacing is promising. In this paper,...
Normal-mode helical antennas (NMHA) are well known for achieving high antenna efficiencies in very small sizes when antenna structures are tuned to self-resonant situations. The design equation determining self-resonant structures were developed in free space conditions. However, in practically, NMHA mostly used dielectric or magnetic materials as cores. The design equation for these cases is not...
This paperproposes a novel mobile base station antenna with a dielectric lens radome. The dielectric lens has a function to shape the radiation pattern which is useful to achieve low side lobe characteristics. In designing the dielectric lens, a ray tracing method has been developed in the MATLAB software. In order to achieve a slender lens shape, adequate radiation patterns for the feed radiator...
Radiation patterns of present mobile base station antennas are designed to be low sidelobe characteristics. To achieve this radiation pattern, linear array feeds are employed. For simplicity of antenna configuration, authors considered to replace antenna radome by a lens antenna. The array feed also replaced by a single feed. However, it is considered that lens thickness will be main problem. This...
In mobile base station antennas, linear array antennas are employing and asymmetrical radiation patterns are achieved. For multi frequency use, unequally spaced array configurations are preferable because of reducing grating lobes in higher frequency operations. Previously, radiation pattern synthesis methods were developed for equally spaced array configurations. In radiation pattern synthesis method,...
The radar cross section (RCS) of an airplane is very important subject in a military use. As for a RCS estimation object, a scale down model is often employed for the ease of measurements. Recently, electromagnetic simulations of RCS become very convenient because of developments of high speed calculation methods such as MLFMM and HOBF in electromagnetic simulators employing MoM algorithm. As for...
Theoretical explanations of radiated, dissipated and stored energies of small antennas were shown in a textbook. However, practical values of these energies were not discussed previously. In this paper, these energies are obtained numerically through electromagnetic simulations. As for a study object, a normal-mode helical antenna is utilized, because stored electric and magnetic energies are simultaneously...
Theoretical treatments of stored and dissipated energies of small antennas were made previously. In this paper, these energies are examined numerically through electromagnetic simulations. As study example, a normal-mode helical antenna is utilized. At the self-resonant conditions, stored electric and magnetic energies are shown to be the same value. And, dissipated energies that are consist of radiated...
As basic studies of low radar cross section (RCS) structures, patch antennas with different terminal loads were selected became of convenience for calculation and measurement. Terminal conditions of the open, short and dummy were previously studied. And effects of low RCS characteristics were shown. In this paper, terminal conditions are expanded to high ohmic resistances. Effects of RCS reductions...
In multi-band base station antennas, interference toward neighboring cells at low operating frequency increases since tilting angle is frequency-independent and beamwidth in the vertical plane increases as decreasing the operating frequency. This paper presents a new low-profile phase shifter which comprises non-linear frequency-dependent characteristics. The proposed phase shifter is composed of...
To enhance the dynamic range of monostatic RCS measurement in compact anechoic chamber, this paper presents the quantitative evaluation of simple CW measurement method by using transmitting and receiving antennas. The mutual coupling is reduced by several approaches such as the separation between antennas, suppressing the sidelobe level, and inserting the shielded conductor. The measurable maximum...
In this paper, a simplified specific absorption rate (SAR) measurement method using a broadband wave absorber phantom is investigated for handset antennas. The antenna factors are determined by using finite-difference time-domain (FDTD) analysis to obtain the electric-field intensity from the electric voltage of the probe in the wave absorber at 835 and 1,950 MHz. The measured electric-field intensity...
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