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The accurate estimation of clutter covariance matrix (CCM) is essential in designing a radar detector/filter to suppress sea clutter. This estimation might not be easily accomplished because of the scarcity of valid training vectors adjacent to the range cell under test (CUT). We propose a new CCM estimation algorithm that is derived by modeling time-series clutter returns into a clutter Doppler spectrum in the frequency domain and exploiting mutual independence among spectral components. To justify its excellence over the conventional sample covariance matrix (SCM) algorithm, we design two filters—a maximum signal-to-interference-plus-noise ratio (SINR)-based filter and a whitening filter—that use the estimated CCMs and compare their performance in a numerically simulated sea clutter scenario. Comparisons are made by showing the eigenvector spectra of the estimated CCMs and the frequency responses and outputs of the filters. Moreover, SINRs at the target Doppler bin are examined and compared with a theoretical, analytically derived SINR.

In the current paper, we propose a new modeling algorithm to analyze the coupling between an incident electromagnetic field (EMF) and a twisted conducting line, which is a kind of non-uniform line. Typically, analysis of external field coupling to a uniform transmission line (TL) is implemented by the Baum-Liu-Tesche (BLT) equation so that the induced load responses can be obtained. However, it is difficult to apply this method to the analysis of a twisted conducting line. To overcome this limitation, we used a chain matrix composed of ABCD parameters. The proposed algorithm expands the dimension of the previous chain matrix to consider the EMF coupling effectiveness of each twisted pair, which is then applied to multi-conductor transmission line (MTL) theory. In addition, we included a comparative study that involves the results of each method applied in the conventional BLT equation and new proposed algorithm in the uniform two-wire TL case to verify the proposed method.

In order to execute coherent Doppler processing in a high range-rate scenario, whether it is for detection, estimation or imaging, range walk embedded in target return should be compensated first. In case of a bistatic radar geometry where a transmitter, a receiver and a target can be all moving, the extent of range walk depends on their relative positions and velocities. This paper presents a coherent Doppler processing algorithm to achieve target detection and Doppler frequency estimation of a target under a bistatic radar geometry. This algorithm is based on the assumption that a target has constant Doppler frequency during a coherent processing interval (CPI). Thus, we first show under what condition the assumption could be valid. We next develop an algorithm, along with its implementation procedures where the region of range walk, called a window, is manipulated. Finally, the performance of a proposed algorithm is examined through simulations.

Range walk has been a major problem in achieving correct Doppler processing. This frequently occurs when range variation is severe just like in a bistatic radar or in high speed target scenario. This paper presents a range walk compensated range-Doppler processing algorithm applicable to the bistatic radar. In order for the compensation, a range-domain interpolation is applied for range compressed signal so that Doppler processing is performed along the evenly time-spaced range bins that contain target returns. Under a bistatic radar scenario, the proposed algorithm including a range domain pulse compression is mathematically described. Finally, the validity of the algorithm is demonstrated by simulation results showing the superiority of a SCDP(Squint Cross-range Doppler Processing) over an uncompensated Doppler processing.

This letter presents a new design concept of the digital video broadcast-handheld (DVB-H) antenna using the folder-type chassis and coupling element on a ferrite. By utilizing the chassis as a radiator in conjunction with a compact coupling element on a ferrite, the antenna achieves DVB-H operation without an additional matching circuit. The measured result shows the wide bandwidth of 250 MHz (VSWR< 6) with sufficient peak gains over -5 dBi in the DVB-H band.

A compact ultrawideband (UWB) antenna with a band-notch function is proposed for laptop applications. The band-notch function is realized by a half-wavelength parasitic element printed on the rear side of the substrate. The impedance bandwidth (VSWR < 2) of the antenna is 3.1 ~ 11.4 GHz (114%) with a notched frequency from 5.05 to 5.90 GHz. The antenna has a fairly good omnidirectional pattern, and the average gain is -3.0 ~ -1.2 dBi over the UWB frequency band except for the notched frequency band. The performance of the proposed antenna is confirmed by simulation and measurement results.

This paper presents a dual-band (2.4 GHz, 5.2/5.8 GHz) WLAN antenna for laptop applications. The proposed antenna consists of the folded-dipole structure operated at higher band and two arms operated at lower band. The radiation pattern of a proposed antenna is orthogonal to that of a conventional monopole at all operating frequency bands.

It's an important issue that estimation of signal direction for radar or communication system. And it was researched for military and commercial. Generally, it's a method that estimate to direction of signal by use each signal of array sensors. It called to DOA(Direction Of Arrival). For basically, there are Beamforming, Capon, Linear-prediction method. And such methods are being researched like Least-mean square method, MUSIC, ESPRIT. [1][2][3] But there are some problems as implemented in DOA(Direction of Arrival) with array antennas unlike other types of sensor. For these reasons, it is difficult to apply previously researched theory like DOA to RF-SYSTEM. In this paper, we will propose the method that can find azimuth(Ф) and elevation(θ) angles with one dimensionally linear array based on MOM.

A diversity antenna for a tri-band application is proposed and designed. The proposed diversity antenna consists of two wideband planar inverted-F antennas (PIFAs) and a suspended line between two PIFAs. The measured results show that the proposed antenna has a wide impedance bandwidth (37%) enough to serve a triple band (PCS, UMTS and WiMAX), a high radiation efficiency (> 50%), and a low correlation coefficient (< 0.2).

This paper presents a structure of the Frequency Selective Surface (FSS) to improve the isolation between donor antenna and coverage antenna for indoor WCDMA repeater systems. The repeater system has two linearly polarized antennas backed with the reflectors. The proposed FSS is embedded into reflectors aligned with the cross-polarization of each antenna. The isolation with the FSS is enhanced overall more than 6 dB at WCDMA band, compared to that without the FSS.

An internal PIFA/slot antenna for quad-band mobile handset applications is presented. The quad-band operation for the bar-type mobile handset is obtained by the resonant modes of the slot antenna in conjunction with those of the PIFA. The proposed antenna has a compact size of 42×10×4 mm3. The quad-band operation includes GSM850 (824–894 MHz), GSM900 (880–960 MHz), DCS1800 (1710–1880 MHz), and PCS1900 (1850–1990 MHz).

A crab shaped tag antenna which has a better performance than conventional label type of tag antenna is proposed for UHF band RFID systems. The proposed antenna is a dipole with T-matching network, and parasitic loop is inserted to the T-matching network. The antenna is analyzed by simulator, Ansoft HFSS software, and the measured results based on backscattering method are presented.

UHF band RFID tag antenna which has a similar radiation pattern of the electrically small loop antenna is presented. The structure of the proposed tag antenna is a small circular dipole array on the xy-plane, and the antenna is fed by inductively coupled loop to flow a uniform amplitude and in phased current along its circumference. Since its radiation pattern has an omnidirectional pattern in the xy-plane, the proposed tag antenna can reduce the interference among adjacent tag antennas arranged parallel to xy-plane.

UHF-band radio frequency identification (RFID) antenna for mobile handset applications is presented. The proposed antenna consists of a radiating element and a parasitic element connected to the ground plane. The radiation pattern of proposed antenna is orthogonal to that of a monopole antenna. The impedance bandwidth (902 MHz ~ 923 MHz) covers a Korea mobile RFID service (908.55 MHz ~ 913.95 MHz). The measured antenna peak gain is -0.37 dBi at 911 MHz.