• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.87-92
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• 2002

A short-ended electromagnetically coupled coaxial dipole array antenna is investigated theoretically. The antenna has an advantage of structural simplicity. The integral equations are derived for the proposed structure by use of the Fourier transform and mode expansion, and the simultaneous linear equations are obtained. The slot electric field and strip current are obtained by solving the simultaneous linear equations. The effects of slot and strip numbers on the radiation efficiency, beamwidth and directivity gain of the antenna are presented.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.17-27
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• 1995

In this paper, Finite Difference Time Domain (FDTD) method is used to analyze characteristics of the electromagnetically coupled broadband microstrip antenna, and to optimize the antenna parameters. By using short tuning stub in feedline, electromagnetically coupled microstrip antenna shows broadband (approximatcly equal 13%) characteristics, and the characteristics are varied as a function of length, width, and position of the tuning stub. Operating frequency, return loss, VSWR and input impedance are calculated by Fourier transforming the time domain results. Measurement data from fabricated electromagnetically coupled microstrip antenna are compared with FDTD results and are shown to be in good agreement. After optimization of the parameters, maximum bandwidth of about 15% is achieved.

• Journal of electromagnetic engineering and science
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• v.18 no.2
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• pp.129-135
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• 2018

This paper proposes a design of small controlled reception pattern antenna (CRPA) arrays using circular microstrip loops with frequency-insensitive characteristics. The proposed array consists of seven identical upper and lower circular loops that are electromagnetically coupled, which results in a frequency-insensitive behavior. To demonstrate the feasibility of the proposed feeding mechanism, the proposed array is fabricated, and its antenna characteristics are measured in a full-anechoic chamber. The operating principle of the proposed feeding mechanism is then interpreted using an equivalent circuit model, and the effectiveness of the circular loop shape is demonstrated by calculating near electromagnetic fields in proximity to the radiator. The results confirm that the proposed feeding mechanism is suitable to have frequency-insensitive behavior and induces strong electric and magnetic field strengths for higher radiation gain in extremely small antenna arrays.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1168-1177
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• 2004

This paper presents the characteristics of the electromagnetically coupled small broadband disk-loaded monopole antenna with multiple shorting pins. The electromagnetically coupled monopole antenna can achieve broad bandwidth by controlling resonant frequency of the rectangular disk-loaded monopole and a probe with the spiral strip line monopole. The number and arrangement of the shorting pin affect the capacitance of the disk. The variation of the capacitance changes resonant frequency of the antenna, and therefore, its electrical sizes and frequency bandwidth are also affected. The antenna with three shorting pins has a volume of $0.094\lambda_0{\times}0.094\lambda_0{\times}0.094\lambda_0$ in electrical length and the frequency bandwidth of $26.8\%\;for\;VSWR\leq2$ with the center frequency at 2.556 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.7
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• pp.653-660
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• 2004

This paper presents monopole antenna with electromagnetically coupled feed and its equivalent circuit model. The proposed structure is consists of a rectangular disk-loaded monopole and a probe with rectangular spiral strip line feed. The rectangular disk-loaded monopole is represented by parallel RLC resonant circuit and the probe with rectangular spiral strip line feed is represented by series RLC resonant circuit. Therefore broad bandwidth can be achieved through electromagnetic coupling between these structures that generate two resonances within close frequency range. The antenna with electrical dimensions of only 0.075λ$\sub$0/${\times}$0.075λ$\sub$0/${\times}$0.075λ$\sub$0/ has 16.5 % fractional bandwidth for VSWR$\leq$2 at a center frequency of 2.038GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.26-35
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• 1996

In this paper, characteristics of the electromagnetically coupled broadband microstrip antennas are analyzed by the Finite Difference Time Domain (FDTD) method, and antenna para- meters are optimized to get maximum bnadwidth. By using short radial tuning stub in microstrip feedline, electromagnetically coupled microstrip antenna shows broadband ($\simeq$13%) characteristics, and the characteristics are varied as a function of radius, radial angle, and position of the radial tuning stub. Operating frequency, return loss, VSWR and input impedance are calculated by Fourier transforming the time domain results. After optimization of the parameters, maximum bandwidth of the radial stub tuning microstrip antenna is about 15% and the ripple char- acteristic of the VSWR is better than the rectangular tuning stub microstrip antenna.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1459-1467
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• 1997

The current on the thin planar structure as an element of the transversely fed electromagnetically coupled(EMC) microstrip dipole array antenna is obtained by using the integral forms of the finite difference time domain(FDTD) method. This method was applied to calculating the optimum current distribution (Doplh-Tchebyscheff distribution) of each dipole element on the feed line as a function of their offset positions for the narrow main beam width and the side beam level below -20 dB. The current on each dipole substitutes for the electric and magnetic current densities on the virtual surface of the FDTD calculation to express the far field intensity, the calculation time and the computer memeory can be reduced to about 80% and 1.3 Mbyte, respectively. The calculated radiation patterns are compared to the measured values and these are in good agreement.

• Journal of the Institute of Convergence Signal Processing
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• v.5 no.4
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• pp.317-324
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• 2004

Electromagnetically coupled coaxial dipole (ECCD) array antenna with and without short-ended termination is investigated theoretically. The integral equations are derived for the structure by use of the Fourier transform and mode expansion of radial waveguide. The integrals appearing in the integral equations are evaluated along the branch cut instead of real axis for a faster convergent integral. The effects of slots and dipoles, short-ended termination length, and dielectric coating on the radiation characteristics are presented. Radiation pattern of the structure is also investigated. The results of the present method are compared with those of the commercial EM simulator and good agreement is found.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.6 s.97
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• pp.632-643
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• 2005

This paper presents a folded stripline-fed small broadband disk-loaded monopole antenna with vertical ground plane. The bandwidth of the proposed antenna can be enhanced by electromagnetic coupling between the shorted rectangular disk and the probe with folded strip line. The measured impedance bandwidth of the proposed antenna is $37.6\%$ for $VSWR\leq2$ with the center frequency at 2.313 GHz and has the physical dimensions of only $11mm\times11mm\times11mm$ which corresponds to the electrical length of $0.085\lambda_0\times0.085\lambda_0\times0.085\lambda_0$. For improving the radiation pattern characteristics, rectangular slits are inserted in the vertical ground plane. Rectangular slits affect the currents distribution on the ground plane, so that the antenna radiation in the direction of the ground plane is reduced more than 3 dBi. Gain of the antenna is approximately 2.6 dBi within the bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.7
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• pp.603-607
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• 2009

In this paper, a GPS antenna is designed by using metal film which can be attached on the case of battery without additional space for antenna in GPS band operation. The proposed metal film has a half-wavelength slot radiator. The slot radiator is fed by th electromagnetic field coupled from the GSM850/PCS band antenna. The proposed GPS antenna obtains about 20 MHz bandwidth(VSWR<3) which can cover entire GPS band. The antenna has an average gain of -3.8 dBi.