• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.4
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• pp.35-40
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• 2022

This paper proposes an antenna that is located outside the PCB substrate of an electronic product to enable wireless communication in the ISM band. The PCB designed the T-shaped OPEN-STUB power supply line to be miniaturized so that it does not interfere with parts or interfere with design. The characteristics of the antenna were confirmed in the 2.4GHz and 5.8GHz bands using a T-shaped stub feeder and a spiral structure. The size of the antenna is 5mm in width × 6.5mm in length, and the thickness of the PCB is 1.2T. As a result of measurement of the manufactured antenna, it was possible to obtain a return loss of -10dB or more at 2.4GHz and 5.8GHz. In the E-plane, the gain was -4.45 dBi, and in the H-plane, the gain was -1.05 dBi. Therefore, the proposed small antenna for wireless communication showed excellent performance.

• Journal of IKEEE
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• v.27 no.4
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• pp.405-410
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• 2023

This paper presents a novel method of implementing a dual-band antenna using a square patch with an inset feed structure. The proposed method is to simply design a dual-band antenna using an asymmetric inset structure with different lengths of slots dug into the patch for inset feeding. To verify the proposed method, a dual-band inset patch antenna supporting 1.57 GHz GPS and 2.4 GHz WiFi bands was designed and manufactured on a 1 mm thick FR4 substrate. From measurement, it was confirmed that the frequency bands of the antenna that satisfy a return loss of -10dB or less are 1.55~1.57GHz and 2.41~2.45GHz, which has dual-band characteristics. Using the proposed method, it is possible to simply implement a dual-band antenna using inset feeding, and it is expected to be utilized in a variety of application fields.

• International Journal of Computer Science & Network Security
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• v.24 no.2
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• pp.53-58
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• 2024

This paper presents a novel miniaturized 3-D cubic antenna for use in wireless sensor network (WSN) application. The geometry of this antenna is designed as a cube including a meander dipole antenna. A truly omnidirectional pattern is produced by this antenna in both E-plane and H-plane, which allows for non-intermittent communication that is orientation independent. The operating frequency lies in the ISM band (centered in 2.45 GHz). The dimensions of this ultra-compact cubic antenna are 1.25*1.12*1cm3 which features a length dimension λ/11. The coefficient which presents the overall antenna structure is Ka=0.44. The cubic shape of the antenna is allowing for smart packaging, as sensor equipment may be easily integrated into the cube hallow interior. The major constraint of WSN is the energy consumption. The power consumption of radio communication unit is relatively high. So it is necessary to design an antenna which improves the energy efficiency. The parameters considered in this work are the resonant frequency, return loss, efficiency, bandwidth, radiation pattern, gain and the electromagnetic field of the proposed antenna. The specificity of this geometry is that its size is relatively small with an excellent gain and efficiency compared to previously structures (reported in the literature). All results of the simulations were performed by CST Microwave Studio simulation software and validated with HFSS. We used Advanced Design System (ADS) to validate the equivalent scheme of our conception. Input here the part of summary.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.11-18
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• 2024

This paper presents a procedure to optimize the design of 70GHz band array antenna for automotive short range radar sensor applications using Chebyshev polynomials. SRR(: Short Range Radar) systems require a wide angle width and low Side lobe level to detect targets within close proximity while ensuring a high Field of View(FoV). The optimized antenna operates in the 76 to 81GHz frequency range, and to reduce the antenna size, we arranged 12 patches in series, achieving an SLL of 10dB, angle with of 112.5o, gain of 15.4dB and an input return loss of less than -10dB at 78GHz. In this paper, we proceed with antenna design for SRR using Chebyshev polynomials, and present an optimal design for antenna structures to be used in MRR(: Medium-Range Radar) and LRR(: Long Range Radar) applications based on this paper

• Journal of IKEEE
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• v.28 no.1
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• pp.33-37
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• 2024

In this paper, we report the design and the measurement of a X-band low noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) using a 0.25 ㎛ gate length microstrip GaN-on-SiC high electron mobility transistor (HEMT) technology. The developed X-band GaN-based LNA MMIC achieves small signal gain of 22.75 dB ~ 25.14 dB and noise figure of 1.84 dB ~ 1.94 dB in the desired band of 9 GHz to 10 GHz. Input and output return loss values are -11.36 dB ~ -24.49 dB and -11.11 dB ~ -17.68 dB, respectively. The LNA MMIC can withstand 40 dBm (10 W) input power without performance degradation. The chip dimensions are 3.67 mm × 1.15 mm. The developed GaN-based LNA MMIC is applicable to various X-band applications.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.323-332
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• 2009

In this paper, we introduce a modified short-circuited stub bandpass filter suitable for ultra-wideband(UWB) applications utilizing low temperature co-fired ceramic(LTCC) technology. By modifying the conventional short-circuited stub bandpass filter structure with stubs and connecting lines of lower characteristic impedances, the number of stubs has been reduced from 5 to 2 on a high dielectric constant substrate($\varepsilon_r$ = 40). A wireless local area network (WLAN) stopband in the frequency range of 5.15 to 5.825 GHz has been inserted into the filter characteristic using three short-circuited coupled lines. The filter has been measured with an insertion loss less than 1.0 dB and return loss better than 10 dB in the pass bands. A bandwidth ratio of 109.49 % has been achieved. Measurement results agree well with simulation results. The dimensions of the filter are $4{\times}8{\times}0.57\;mm^3$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.151-158
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• 2012

This paper proposes a H-plane 8-way rectangular waveguide power divider using Y-junction. A general N-way power divider can be composed of multi-stage T-junctions. However, if the distances of output ports are close, the matching characteristic is not improved by using only T-junctions because of space limitation. In this case, since other types of 3-port junctions should be used to final output stage, Y-junctions are used with T-junctions in this paper. The proposed Y-junction uses the tapered-line impedance transformer and inductive irises to improve impedance matching characteristic. The 8-way power divider using Y-junction is fabricated and measured. The measured return loss and insertion loss from input port to output port are -30.8 dB and -9.3 dB at operating frequency, respectively. The measured maximum phase difference is about $1^{\circ}$. Therefore, the proposed power divider will be useful to apply to various microwave systems, which need to divide the input power equally, such as feed networks for array antennas.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.3
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• pp.59-64
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• 2002

In the RFID system using ISM-band, The tag mounted at the object has used the DC power by rectifying the RF signals of the small antenna for operating the micro-controller and memory. The performance of the tag would be reduced because of the second harmonics generated by the nonlinearity of the semiconductor and the spurious signal excited the high order mode of the antenna. This paper has realized the novel type low-pass filter with "the Stub-I type DGS slot structure" to improve the efficiency of the tag by suppressing the harmonics. The optimized frequency character at the pass-band/stop-band has obtained by tuning the stub width and slit width of I type slot. The measured result of the LPF has the cutoff frequency 3.25 GHz, the insertion loss about -0.29~-0.3 dB at pass-band 2.4 GHz~2.5 GHz, the return loss about -27.688~-33.665 dB at pass-band with a good performance, and the suppression character is about -19.367 dB at second harmonics frequency 4.9 GHz. This DGS LPF may be applied the various application as the RFID, WLAN to improve the efficiency of the system by suppressing the harmonics and spurious signals. 

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.65-70
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• 2008

We design and fabricate the 94 GHz Coplanar waveguide(CPW)-to-rectangular waveguide transition that is transmits signal smoothly between the CPW, which is a popular transmission line of the planar circuits, and rectangular waveguide for the 94 GHz transceiver system. The proposed transition composed of the unilateral fin-line taper and open type CPW-to-slot-line transition is based on the hard and inflexible sapphire for the flip-chip bonding of the planar MMICs using conventional MMIC technology. We optimize a single section transition to achieve low loss by using an EM field solver of Ansoft's HFSS and fabricate the back- to-back transition that is measured by Anritsu ME7808A Vector Network Analyzer in a frequency range of $85{\sim}105$ GHz. From the measurement and do-embedding CPW with 3 mm length, an insertion and return loss of a single-section transition are 1.7 dB and more an 25 than at 94 GHz, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.347-353
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• 2018

In this paper, we studied a design method for a band-pass waveguide filter with a modified H-type resonant iris (RI) placed in a thin transverse wall of a rectangular waveguide. The horizontal straight gap at the center of a conventional H-shaped iris is modified to a U-shaped one to increase the equivalent capacitance, and the equivalent inductance is improved by changing the vertical two straight slots into C-shaped ones. From some simulation results for the frequency response of the proposed RI, it was observed that the proposed iris was advantageous for reducing its size and having better cutoff, compared to typical H-shaped one. Equivalent inductance, capacitance, and quality factor of the proposed RI were extracted to analyze its performance. A third-order band pass filter using the proposed modified H-shaped iris was designed and, it was observed that the filter operated in the frequency range of 9.18-9.84 GHz with its insertion loss of 0.3 dB and return loss of 14 dB.