• Journal of electromagnetic engineering and science
• /
• v.10 no.1
• /
• pp.18-24
• /
• 2010

A Ka-band microstrip array antenna for wide-range detection of moving targets is analyzed through a photonicassisted reactive-near-field characterization technique. The antenna array employs a 3-dB-tapered feed network to suppress the sidelobe level while retaining a wide azimuth beamwidth for a wide detection range. The relative nearelectric field patterns of the array and its 3-dB-tapered feed lines have been measured using an electro-optic fieldmapping technique for minimally invasive millimeter-wave sensing. A number of typical limitations on the technique, involving bandwidth, low signal-modulation depth, and high laser-induced noise in high-frequency applications, have been overcome by suppressing the carrier portion of the optical interrogation beam.

• Journal of the Institute of Convergence Signal Processing
• /
• v.9 no.2
• /
• pp.141-145
• /
• 2008

When the current flows to parallel lines with different length, it is researched that the radiation is occured by the common-mode current radiates, and the small light weight antenna composed of dual elements by using the principle is proposed. However, there is a problem in production about this antenna because this liner antenna is structured by combining with wires. In this paper, we improved this liner antenna, and designed the plane antenna composed of dual elements with different length in the plane printed board to produce and to design easily. Furthermore, the antenna with the wide-band characteristic is also designed in the same board. The radiation pattern is similar to the dipole antenna on account of designing the triangular patch S, the notch and two tapers in patch S, the notch and two tapers in the antenna element. In result, it was able to design the antenna working wider band-width(the bandwidth ratio about 58%, $VSWR{\le}2$).

• Journal of electromagnetic engineering and science
• /
• v.19 no.1
• /
• pp.56-63
• /
• 2019

Typical negative group delay circuits (NGDC) are analyzed in terms of signal attenuation, group delay, and bandwidth using S-parameters. By inverting these formulations, we derive and present the design equations (for NGD circuit elements) for a desired specification of the two among the three parameters. The proposed design method is validated through simulation examples for narrow- and wide-band pulse inputs in the time and frequency domains. Moreover, an NGDC composed of lumped elements is fabricated at 1 GHz for measurement. As a function of frequency, the circuit-/EM-simulated and measured group delays are in good agreement. The provided simple NGDC design equations may be useful for many applications that require compensations of some signal delays.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.7
• /
• pp.729-736
• /
• 2011

In this paper, we propose a varactor-diodeless voltage-controlled oscillator operating at X-band, and verify the possibility of applying to a receiver for microwave radar signal detection applications. The proposed VCO is realized by only single RF BJT device as a varactor diode is substitued by a intrinsic collector-base PN-junction of the active device which is used to generate negative resistance. The fabricated VCO meets the specification of the receiver, which has a 11.20~11.75 GHz tuning bandwidth with respect to the tuning voltage, 1.0~7.0 V, output power of 9.0~12.0 dBm and linear frequency tuning performance.

• Journal of the Korean Institute of Navigation
• /
• v.19 no.2
• /
• pp.107-113
• /
• 1995

Since the most of the mal-functions in the industrial equipments controlled by processors have been occured by the Electrical Fast Transient(EFT), the International Electrotechnical Commision(IEC) prepare the dummy signal to test the immunity level of the equipments controlled by processors and recommend it for the measuring. In this paper, the defined dummy EFT signal by IEC are analyzed by the spectrum analyzer in the frequency domain and studied the developed countermeasuring parts. The new developed parts are consist of the feedthrough capacitors ( $C_y$ type ) in the input and materials with high permeaility which was wound or inserted in the second layer of the Power Cable in order to increase Common Mode inductance. And it is compared inserted Permalloy to material with high permeability increasing Common Mode inductance. We could gotten a excellent insertion loss on the wide band against EFT signal. Especially, we confirm that countermeasuring Power Cable have been an excellent dynamic characteristics in computer system above the 3.6Kv. This new parts could be effectively used for industrial, MIL, and medical equipments to reduce a mal-functions on the site. Furthermore, these parts also have a good characteristics for EMI countermeasuring over the 60MHz up to several GHz band, they are also expected to be used for all kind of EMS test with IEC801-2, 3, 5 and 6 on the power distributed line.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.17 no.6
• /
• pp.539-547
• /
• 1992

Considering the field of high frequency or broad-band signal filtering with high speed, we pro-pose optical fiber filters which consist of directional couplers and optical fiber delay elements. Fiber delay line signal processor Is operated with Incoherent optical carrier because of Its simplicity. Due to the characteristics of the directional coupler which Is basic element of optical fiber filter a new design method which Is different from that of usual digital filter is required. By considering the characteristics of directional coupler and in order to make good use of the optical signal energy, we have given the design formulae and the conditions of optical fiber filters for the direct and the lattice form.

• Journal of Advanced Navigation Technology
• /
• v.12 no.2
• /
• pp.146-153
• /
• 2008

Due to the extremely short pulse in the Ultra-Wideband (UWB) technology, the accurate synchronization acquisition method is very important for both high data-rate WPAN and low data-rate WPAN. In this paper, we propose the synchronization acquisition algorithm based on two-step signal search method to acquire the synchronization in the UWB multi-path channel. At the first step, the search window is divided by two and the window that has higher power is chosen as a next search window. This operation is repeated until the measure power of the search window is smaller than the threshold value. At the second step, we employ Linear Search algorithm to the search window obtained at the first step for fine search. The proposed algorithm is proved that the synchronization acquisition is faster than the parallel search algorithm and it shows good performance in environment of the SNR extreme changes by the simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.8C
• /
• pp.742-753
• /
• 2005

In this paper, we propose a rapid and reliable signal acquisition scheme for UWB (Ultra Wide Band) systems in typical indoor wireless channels. The proposed scheme is a two-step search with different thresholds and search window applied to a single correlator, where each step utilizes the single-dwell search with the bit reversal. Simulation results in IEEE 802. I5 Task Group .3a UWB indoor wireless channel show that the proposed scheme for the LHWB signals can achieve significant reduction of the required mean acquisition time as compared to the conventional single-dwell bit reversal search and double-dwell bit reversal search with more complex structure employing two correlators for various threshold levels. In addition, it is also observed that the proposed scheme can achieve much faster and reliable signal acquisition in noisy environments.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.3
• /
• pp.19-26
• /
• 2008

We propose a selective detection scheme based on pulse repetition considering the BER (Bit Error Rate) performance and complexity of coherent IR-UWB (Impulse Radio-Ultra Wide Band) systems. To take system complexity into account, the proposed scheme transmits the UWB signals by pulse repetition at the transmitter, like conventional PRC (Pulse Repetition Coding). However, to effectively improve BER performance of the system, the proposed scheme performs selective detection by estimating the SNR (Signal-to-Noise Ratio) of the received pulse-repeated signal at the UWB receiver. Hence, the proposed scheme effectively improves BER performance of the coherent IR-UWB systems without increasing system complexity, as compared to the conventional PRC algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.12C
• /
• pp.1623-1632
• /
• 2004

In this paper, we analyze the performance of linear search and bit reversal search algorithms based on the single-dwell serial search for rapid UWB (Ultra Wide Band) signal acquisition in typical indoor wireless channel environments. Simulation results according to bin spacing and frame interval in IEEE 802.15 Task Group 3a UWB indoor wireless channels show that bit reversal search algorithm achieves much smaller normalized mean acquisition time than linear search algorithm. In particular, it is found that the normalized mean acquisition time of the bit reversal search according to the range of searching termination interval closely matches the ideal case. In addition, we observe that the acquisition performance of bit reversal search algorithm becomes much better as bin spacing gets finer.