Suk-Youb Kang

Antenna Measurement Method in Fresnel Region by

The far-field pattern and gain obtained using the far-field measurement method can be highly accurate when the distance between the source antenna and the antenna under test (AUT) satisfies the Rayleigh far-field criterion. In this letter, we propose an improved Fresnel region measurement method that can be applied in a shortened distance between two antennas. The many Fresnel fields required are captured by changing angle phi of the scanning plane. This scanning involves rotating the roll positioners of the source antenna and the AUT in the same direction and by the same amount, and rotating the azimuth positioner in the horizontal plane. The radiation pattern and gain from the simulation and experimental measurements agreed closely with the reference far-field pattern and gain. The proposed antenna measurement method in Fresnel region by phi-variation scanning can be easily applied to most popular far-field measurement systems without any additional cost.

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In this paper, a novel antenna having a miniaturized aperture is proposed. The substrate including a split-ring resonator (SRR) array has been inserted into a size-reduced open-ended waveguide. For a low return loss and high radiation efficiency, the ring arrangement has been optimized, and a stepped transition using H-plane discontinuity is proposed. The proposed antenna achieves a 70% aperture reduction compared to a conventional standard waveguide antenna. The return loss was deeply dropped at three frequencies, and a reasonable gain was presented. The aperture-miniaturized antenna can be used in many antenna applications such as near-field measurements.

-Variation Scanning

In this work, a short wavelength microstrip line employing periodically arrayed capacitive elements (PACE) on GaAs monolithic microwave integrated circuit (MMIC) was developed for application to miniaturized on-chip passive components. The microstrip line employing PACE showed a wavelength much shorter than conventional transmission line. Concretely, the wavelength of the microstrip line employing PACE was only 10 % of conventional microstrip line on GaAs MMIC. Using the microstrip line employing PACE, a highly miniaturized impedance transformer was fabricated on GaAs MMIC. The impedance transformer showed good RF performances in a broad band from S to X band. Concretely, the return and insertion loss are −28 and −1.4 dB, respectively, at a center frequency of 7 GHz, and return loss values better than −10 dB were observed from 3.2 to 9.2 GHz, and insertion loss values of −1.5 ± 0.5 dB were observed in the above frequency range. The size of the impedance transformer was 0.042 mm2, which is 0.95 % of the size of the conventional transformer on MMIC.

Aperture-miniaturized antenna loaded with split ring resonator array

The meander line employing periodic ground structure (MLEPGS) was fabricated on GaAs substrate for application to miniaturization of RF components on MMIC, and its RF characteristics were thoroughly investigated. The MLEPGS with a length of /8 showed loss less than 0.72 dB up to 20 GHz, which was low enough for application to RF passive components. The MLEPGS showed much higher propagation constant and effective permittivity than conventional meander line. Concretely, the MLEPGS with of 20 μm showed of 1.08~20.85 rad/mm and of 2703~2479 from 1 to 20 GHz, while the conventional meander line showed of 0.18~3.36 rad/mm and of 74.2~64.7 in the same frequency range. According to the result, the size of the /4 transmission line employing the MLEPGS was 0.151 mm2, which was 3.5% of the size of the transmission line employing conventional meander line.

An ultra-compact on-chip impedance transformer fabricated using a novel microstrip line employing periodically arrayed capacitive elements on MMIC

In this paper, Using the silicon CMOS technology, direct conversion mixer was fabricated on silicon substrate for a realization of the long distance wireless power transmission system. The size of the mixer is 0.8 mm × 0.5 mm. The input frequency of mixer is 24 GHz, and converted BB frequency is 30 MHz. The conversion loss and output power of mixer was -9 dB and -10 dBm, respectively.

A Basic Study on RF Characteristics of Meander Line Employing Periodic Ground Structure on GaAs MMIC for Application to Miniaturization of RF Components

This paper describes the 6-way power divider to be used as a feeding structure of the waveguide array antenna generating the plane wave at the near distance. The SMA connector has been connected at the center of the power divider in order to feed the radiating element. The six output ports made of waveguide are positioned on the peripheral of the divider. This paper proposes the method utilizing the inductive post in order to decrease the return loss. The height of the feeding pin, the diameter of the inductive post, and the distance between the feeding pin and inductive post have been investigated, and as a result, the power divider has been optimized. The simulated and measured results show the low return loss of about -40 dB. The calculated and measured transmission coefficients are -7.78 dB and -8.06 dB, respectively. The output power of the six waveguide port show equal-amplitude and equal-phase distribution. Since the power divider proposed in this paper can be expanded to the divider having several output ports, it could be easily applied to the various array antennas.

Direct Conversion Mixer IC for Application to Long Distance Wireless Power Transmission

MMIC (monolithic microwave integrated circuit) chip set was developed for application to wireless PAN. Concretely, cascade type transceiver mixers employing GaAs p-HEMT were fabricated on GaAs substrate. The mixer MMICs showed good RF performances. Concretely, the conversion gain of the receiver mixer was 9.6 dB at a LO input of 8 dBm, and 9.6 ± 1.6 dB at a RF frequency range of 62.5 - 63.5 GHz. The chip size of the receiver mixer was 2.7 mm x 1.35 mm. The conversion gain of the transmitter mixer was 6.5 dB at a LO input of 8.5 dBm, and 6.5 ± 0.25 dB at a IF frequency range of 1.9 - 2.9 GHz. The chip size of the transmitter mixer was 2.7 mm x 1.35 mm. 0.2 μm

X-Band 6-Way Waveguide Power Divider Using Inductive Post

This paper proposes a dereverberation system for speech enhancement using modified linear prediction (LP) residual in the reverberant room condition. We obtain a delay-and-sum beamformer and new LP residual signal using modified LP residual combination, which derived from weighting of the LP residual and the Hilbert transform of LP residual.

Tranceiver Mixer MMICs Employing Cascode Circuit Structure for Personal Area Network (PAN) Applications

In this work, spiral inductor structures employing SiN film were fabricated on GaAs substrate for a suppression of LO and its second harmonic leakage signals. Concretely, they were properly designed so that the self-resonance frequency was accurately tuned to LO and its second harmonic frequency, and they were integrated on the downconverter MMIC. Owing to the optimally designed on-chip spiral inductor filters, the downconverter MMIC showed a highly suppressed LO leakage power of −35 dBm and second harmonic LO leakage power of −53 dBm without external filters.