Dong-yeon Kim

Design of SIW Cavity-Backed Circular-Polarized Antennas Using Two Different Feeding Transitions

Two circular-polarized circular patch antennas which have novel feeding structures such as a substrate integrated waveguide (SIW), a cavity-backed resonator and two different feeding transitions, are proposed and experimentally investigated in terms of electrical performances, including reflection coefficients, optimized parameter values, circular polarized antenna gain, axial ratios and radiation patterns. By inserting asymmetrical inductive via arrays into the interface region between the circular patch and SIW feeding structure, it is found that an enhancement of input impedance bandwidth has been achieved. In addition, in order to check the effects of feeding transition types on the electrical performances of the main radiator, two different feeding transitions, namely microstrip-to-SIW and coax-to-SIW, have been studied by considering reflection coefficients, gain, axial ratios and radiation patterns. As a result, it is experimentally proved that a broadband impedance bandwidth of 17.32% and 14.42% under the criteria of less than VSWR 2:1 and 1.5:1, respectively, have been obtained and an RHCP axial ratio of 2.34% with a maximum gain of 7.79 dBic has been accomplished by using the proposed antenna with coax-to-SIW transition operating at the X-band of 10 GHz center frequency.

Bandwidth Enhancement of Cavity-Backed Slot Antenna Using a Via-Hole Above the Slot

A novel technique for the bandwidth enhancement of a cavity-backed slot antenna is presented. A via-hole located above the slot creates an additional resonance at a higher frequency by shortening the effective length of the slot. The location of the via-hole can be changed to determine the second resonance frequency of the antenna. With proper placement of the via-hole, the bandwidth of cavity-backed slot antenna can be increased. The fabricated antenna has a 60% wider bandwidth than a cavity-backed slot antenna without a via-hole. The proposed antenna maintains high radiation efficiency and gain, which are characteristics of a conventional cavity-backed slot antenna. The proposed technique is especially useful for enhancing the bandwidth of a cavity-backed slot antenna in a limited area.

Design of a 45

In this letter, a new type of resonant series slot array antenna for Ka-band for 45° linear polarization (LP) is described. Sixteen radiating slots, tilted at an angle of 45°, are separated by one-half guided wavelength due to use of the alternating inductive and capacitive load slot pairs. These alternating reactance slot pairs allow this novel antenna to achieve impedance matching, uniform field excitation, and suppression of grating lobes simultaneously. The antenna is designed and fabricated using substrate integrated waveguide (SIW) technology to overcome the drawbacks associated with conventional metallic waveguide antennas. The measured impedance bandwidth, maximum gain, and sidelobe levels are 2.7%, 15.64 dBi, and 15.36 dB, respectively, at the design frequency. The measured data are in agreement with the theoretical calculations and demonstrate the validity of the design technique for the proposed antenna structure.In this letter, a new type of resonant series slot array antenna for Ka-band for 45° linear polarization (LP) is described. Sixteen radiating slots, tilted at an angle of 45°, are separated by one-half guided wavelength due to use of the alternating inductive and capacitive load slot pairs. These alternating reactance slot pairs allow this novel antenna to achieve impedance matching, uniform field excitation, and suppression of grating lobes simultaneously. The antenna is designed and fabricated using substrate integrated waveguide (SIW) technology to overcome the drawbacks associated with conventional metallic waveguide antennas. The measured impedance bandwidth, maximum gain, and sidelobe levels are 2.7%, 15.64 dBi, and 15.36 dB, respectively, at the design frequency. The measured data are in agreement with the theoretical calculations and demonstrate the validity of the design technique for the proposed antenna structure.

Design of a Compact Tri-Band PIFA Based on Independent Control of the Resonant Frequencies

The application of multiple folded radiator to independent frequency control of a compact tri-band planar inverted-F antenna (PIFA) composed of three resonant frequencies, global system for mobile communication (GSM900, 880-960 MHz)/digital communication system (DCS1800, 1710-1880 MHz)/Satellite Digital Mobile Broadcasting (Satellite DMB, 2605-2655 MHz) are treated with the optimized parameter values. The proposed antenna has been designed and analyzed by using commercially available softwares, CST MWS based on the finite-difference time-domain algorithm, High Frequency Structure Simulator (HFSS) based on the finite element method algorithm and a simple resonant equation, respectively. It is also seen that good isolation characteristics and independent frequency control can be accomplished by using the separation of folded parts operating at each different frequency. In addition, the return loss has been measured and compared between measured and simulated data under the criterion of VSWR less than 3. The radiation patterns in each service are the same as the omnidirectional characteristics and the maximum gains are 1.19, 2.93, and 1.48 dBi at 0.92, 1.8, and 2.63 GHz, center frequencies of each service, respectively.

Bandwidth and Efficiency Enhancement of Cavity-Backed Slot Antenna Using a Substrate Removal

A technique for enhancement of bandwidth and efficiency of a cavity-backed slot antenna is proposed. The bandwidth of the cavity-backed slot antenna depends on the Q of the slot and the cavity. The proposed technique removes the substrate under the slot to decrease the capacitance of the slot. Because a half-wavelength slot is considered a parallel resonant circuit at resonant frequency, lowered capacitance increases the bandwidth of the antenna. Antenna efficiency also can be enhanced by the proposed technique. The dielectric loss, which is produced by the E-field across the slot, is effectively decreased by removing the substrate under the slot. Various simulation results of demonstration of the proposed technique are given. The proposed antenna, which was fabricated on a 2-mm-height FR-4 substrate, shows 6.2% higher antenna efficiency and 24% wider bandwidth compared to the conventional cavity-backed slot antenna, which has a whole substrate. The proposed technique is effective in enhancing the efficiency and bandwidth of a cavity-backed slot antenna.

A Series Slot Array Antenna for 45

The design method for a standing-wave series slot array antenna with 45°-inclined linear polarization in the Ka-band is presented. The proposed 16 × 8 planar slot array antenna consisted of arrays with alternating reactance slot pairs that could achieve impedance matching and uniform field ex- citation, simultaneously. Furthermore, the grating lobes were effectively suppressed with the help of these radiating units due to the one-half guided wavelength slot spacing. An equivalent circuit analysis was done to evaluate the input impedances of the radiating and feeding lines with the impedance recursive formulas as well as the mode voltages of the radiating slot elements. In addition, a wideband transition with a 30.13% bandwidth under the criteria of less than VSWR 1.5:1 was presented to provide the necessary power with the minimal reflection and to prevent the distortion of the radiation patterns. The proposed planar slot array antenna occupied an aperture area of 57.4× 51.6 mm. The measured bandwidth, gain, and efficiency were 990 MHz (2.88%), 24.3 dBi, and 53.7%, respectively. Furthermore, the side lobe levels (SLLs) were verified for each cutting plane with -13.57 dB and -13.17 dB, respectively. The proposed antenna structure was achieved with a substrate integrated waveguide (SIW) with the low costs and lightweight features.

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In this letter, a new type of resonant series slot array antenna for Ka-band for 45° linear polarization (LP) is described. Sixteen radiating slots, tilted at an angle of 45°, are separated by one-half guided wavelength due to use of the alternating inductive and capacitive load slot pairs. These alternating reactance slot pairs allow this novel antenna to achieve impedance matching, uniform field excitation, and suppression of grating lobes simultaneously. The antenna is designed and fabricated using substrate integrated waveguide (SIW) technology to overcome the drawbacks associated with conventional metallic waveguide antennas. The measured impedance bandwidth, maximum gain, and sidelobe levels are 2.7%, 15.64 dBi, and 15.36 dB, respectively, at the design frequency. The measured data are in agreement with the theoretical calculations and demonstrate the validity of the design technique for the proposed antenna structure.In this letter, a new type of resonant series slot array antenna for Ka-band for 45° linear polarization (LP) is described. Sixteen radiating slots, tilted at an angle of 45°, are separated by one-half guided wavelength due to use of the alternating inductive and capacitive load slot pairs. These alternating reactance slot pairs allow this novel antenna to achieve impedance matching, uniform field excitation, and suppression of grating lobes simultaneously. The antenna is designed and fabricated using substrate integrated waveguide (SIW) technology to overcome the drawbacks associated with conventional metallic waveguide antennas. The measured impedance bandwidth, maximum gain, and sidelobe levels are 2.7%, 15.64 dBi, and 15.36 dB, respectively, at the design frequency. The measured data are in agreement with the theoretical calculations and demonstrate the validity of the design technique for the proposed antenna structure.

-Inclined Linear Polarization With SIW Technology

A sidelobe suppression method for a series slot array antenna which radiates 45° -inclined linear polarization is proposed. Axial displacements are employed to create arbitrary excitation coefficients for individual centered-inclined radiating slots along the center line of a broad wall. To verify the proposed design method, we design two types of center-fed linear slot array antennas with a Dolph-Chebyshev distribution for -20 dB and -26 dB sidelobe levels (SLLs) in the Ka band. Furthermore, a cross-validation process involving an equivalent circuit model analysis and electromagnetic full-wave simulation using CST MWS is utilized. The entire structure of the proposed series slot array antenna is fabricated on printed circuit boards (PCBs), including drilling and chemical etching, to secure advantages of miniaturization and cost reduction. The measured realized gains are 15.17 and 15.95 dBi and SLLs are -18.7 and -22.5 dB respectively for two types of fabricated antennas. It demonstrates the validity of the proposed sidelobe suppression method.

Design of a 45

A W-band 8 × 8 slot array antenna is proposed and fabricated by electroforming for high-precision manufacturing. The external mutual coupling between radiating shunt slots is compensated for input impedance matching and a uniform held distribution. The overall antenna aperture area is 473.1 mm2 with slot spacings of 2.8 and 2.64 mm in the transverse and longitudinal direction, respectively. The measured maximum gain is 26.8 dBi and the corresponding antenna efficiency is 81.9% at 94 GHz. The measured impedance bandwidth when the VSWR is less than 2.0 (-10 dB) is 8.3%, with a range from 89.9 to 97.6 GHz.

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A folded, cavity-backed crossed-slot antenna is proposed for antenna miniaturization. The cavity dimensions of a conventional cavity-backed crossed-slot antenna are about a half-guided-wavelength along each side, which is unsuitable in many applications like a handheld device or body area network (BAN). To reduce the size of the cavity, a folded cavity is proposed in this letter. The center plate that divides the cavity into the upper cavity and the lower cavity increases the effective length inside the cavity. Compared to the conventional cavity-backed crossed-slot antenna, a 72.8% size reduction can be achieved using the proposed structure. The proposed antenna also has circular polarization and wideband characteristics, which are the main advantages of a cavity-backed crossed-slot antenna. The proposed technique is especially useful for reducing the lateral dimensions of the cavity.