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This paper presents an analysis of MIMO antennas consisting of notch antenna and loop antenna for a wide area mobile communication system with bi-directional radiation patterns. The notch antenna radiates a horizontally polarized wave while the loop antenna radiates a vertically polarized wave. The MIMO antenna is designed for 4G applications with the resonance frequency at 3.5 GHz. The antenna produces...
Characteristic mode theory (CMT) is an effective method for designing MIMO system. Establishing reliable channel is an important issue in communication systems. And MIMO system based on CMT is one strong candidate among the other approaches. In this paper, some design examples of MIMO antenna on chassis and its coupler structure is shown. The proposed coupler is useful to excite a desired mode from...
In this paper, a Full-duplex (FD) antenna system is presented with a high isolation between the TX and RX antennas. The isolation method is based on utilizing balanced antennas to localize the current on the ground plane and single mode excitation of the ground plane with capacitive coupling elements. The simulation results show a promising isolation level of 75 dB. User impact investigation on the...
This paper presents the characteristic mode analysis of the helmet, which is double hemispherical conductor shell, in order to achieve the omni-directional pattern in the horizontal plane. By deleting the weak part of the electric current on the double hemispherical conductor shell, the shape of the folded dipole is obtained with low resonant frequency.
A new approach for realizing the radiation patterns of antenna systems located on a complex platform is proposed in this paper. The proposed technique is based on the use of Characteristic Basis Functions (CBFs). The CBFs are generated by exciting a number of antenna elements, typically specified by the user, and placed at “allowable” locations on the platform. The Characteristic Basis Function Patterns...
Two different solutions for the characteristic modes (CMs) of lossy structures were previously developed using induced volume currents. The first solution diagonalizes the scattering and perturbation matrices, guaranteeing far-field orthogonality at the cost of imaginary eigenvalues and eigencurrents. The second solution does not perfectly diagonalize these matrices, but maintains real-valued eigenvalues...
This paper proposes the evaluation of the multiple-input multiple-output (MIMO) channel capacity using the theory of characteristic modes (TCM) analysis. First, the mode directivity of the ground plate of a small terminal is analyzed by using TCM. MIMO propagation characteristics are evaluated using the ray tracing method. After that, the channel capacity is calculated using the MIMO propagation characteristics...
The differences between the characteristic modes(CMs) and X modes(XMs) are pointed out then the relations between these two types of modes are discussed through an example of a thin strip dipole. Finally it is concluded that the resonant information of an antenna, including resonant frequency and resonant current, exists only in the imaginal part of the impedance operator (reactance operator) of the...
Characteristic modes (CMs) provide physical insights for antenna design but it is computationally intensive. In this contribution, an interpolation scheme is proposed for frequency sweep of CMs for the first time. Orthogonality of the eigeicurrents is checked using interpolated impedance matrix. Two numerical examples are provided for verification.
Microwave electric field measurement system based on the modulated scattering technique with semiconductor scatterer has been developed. The scattered wave by the scatterer was modulated with the light which has higher energy than the band-gap energy of the semiconductor. By using undoped germanium disk as the scatterer, microwave field could be detected in the frequency range of 1–7 GHz. The sensitivity...
A simple measurement method for the balanced and unbalanced modal power ratios of a small antenna is proposed. Because the conductance corresponding to each mode can be calculated by applying the S-parameter method to the power dissipated at the antenna, the modal power ratio can be obtained by measuring only the 2-port S-parameters. In this paper, we demonstrate a simulation for the analysis of the...
To evaluate specific absorption rate (SAR) of radio devices operated in MHz band, a small loop antenna can be used to calibrate a probe for estimating field intensity in the tissue-equivalent liquid. In our proposed method, field intensity radiated by a small loop antenna can be expressed in terms of its antenna factor in transmitting mode. In this paper, distance property of the antenna factor is...
Recently, the S-parameter method using a vector network analyzer was proposed whereby the differential input impedance of a balanced-fed antenna was obtained. To improve measurement accuracy of the S-parameter method, the dependence on the thickness of the semi-rigid cable used for the measurement jig is obtained from the results of calculations using the FDTD method. Three types of jigs each made...
Recently, the S-parameter method, which is the measurement method of the input impedance of the balanced antenna, has been proposed. However, when the measured frequency rises, measurement accuracy decreases because the influence of the jig cannot be disregarded. To eliminate an influence of the measurement jig, we have proposed the modified open correction using the ABCD-matrix. In this report, to...
A bandpass filter is presented with the multi-step hook resonator structure and use the coupling feed line at input and output port. The slit line is inserted at the end of the multi-step resonator to suppress harmonic frequencies around 7.2 GHz and 9.3 GHz. The proposed band pass filter is used for support the WLAN system at the center frequency of 2.45 GHz. The insertion loss and the return loss...
This paper proposes the triple-band band pass filter for applications of GSM, Wi-MAX, and WLAN systems. The filter comprises of step-impedance resonators (SIRs) connected with capacitive load, which are combined by using cross coupling technique. Additionally, tapered lines are used to connect at both ports of the filter in order to enhance matching for the triple-band resonant frequencies. The filter...
A 5-bit radio frequency micro-electromechanical system (RF MEMS) true-time-delay (TTD) phase shifter operating over frequency ranges 6–12 GHz is designed and fabricated. The TTD phase shifter provides five delay bits: λ, 2λ, 4λ, 8λ, 16λ, the biggest delay-bit time is 1680ps and the total time delay is 3255ps. The circuit uses twenty cantilever RF MEMS switches. The circuit is fabricated on four layers...
Recently, by advance of miniaturization of electronic devices, a ground of a printed circuit board is tend to be small and complicated and the ground may have some defects, such as ground slots. In this paper, we calculated electromagnetic coupling between microstrip lines on different layers in 3 layers printed circuit board with a narrow ground slot. To calculate electromagnetic coupling between...
We investigate a radiation pattern analysis method for reflector antennas using near-field measurements of primary feed. Using the plane-wave spectrum obtained through near-field measurement, it is possible to find the incident electromagnetic field not only at an arbitrary plane, but also at each point of the reflector. This paper describes the analysis method, and verifies its validity by using...
When covering Malaysia area by multi beams in satellite antenna, many feed horns are employed. In a previous designing, severe horn overlapping was shown. In this paper, overlapping problem of feed horn is analytically studied. The relation of feed horn size and feed position displacement is numerically clarified with parameter of the beam separation angle and F/D of a parabolic reflector. As a result,...
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