Chang Won Jung

Reconfigurable scan-beam single-arm spiral antenna integrated with RF-MEMS switches

A fully integrated solution providing scan-beam capability with a single antenna is presented in this paper for the first time. The proposed system includes a reconfigurable rectangular spiral antenna with a set of micro electro mechanical system (MEMS) switches, which are monolithically integrated and packaged onto the same substrate. The system is based on a single-arm rectangular spiral antenna, capable of changing its radiation pattern using radio frequency-MEMS (RF-MEMS) switches. The rectangular spiral and RF-MEMS switches are monolithically integrated on a conventional microwave substrate printed circuit board (/spl epsiv//sub r/=3.27 and tan/spl delta/=0.004) and quartz substrate (/spl epsiv//sub r/=3.78 and tan/spl delta/=0.0002). The spiral is made out of multiple lines, which are interconnected by RF-MEMS switches strategically located along the spiral. On activating these switches, the spiral overall arm length is changed and consequently its radiation beam direction is changed. The two proposed antennas radiate right hand circular polarization (RHCP) and left hand circular polarization (LHCP) for printed circuit board and quartz substrate respectively. The gain of the two antennas varies between 3/spl sim/6 dBi. They both satisfy the 3-dB axial ratio criterion at their operating frequency band, i.e., at 10 GHz and 6 GHz for the printed circuit board and the quartz substrate respectively. To the best of our knowledge, this is the first truly reconfigurable printed antenna design using MEMS devices as active elements integrated in the same low loss substrate. The excellent performance of the proposed system emphasizes the importance of being able to integrate MEMS switches into the same low loss substrate for antenna applications. This technology pioneers the design of arbitrarily shaped reconfigurable antennas including the design of reconfigurable antenna arrays.

Octaband Internal Antenna for 4G Mobile Handset

A compact internal antenna that is composed of a coupled loop with two branch lines is presented. The proposed antenna operates at two wide frequency bands (698 ~ 960 MHz/1710 ~ 2690 MHz) to cover octabands LTE 700/GSM 850/GSM 900/DCS 1800/PCS 1900/WCDMA 2100/LTE 2300/LTE 2500 for the 4G mobile handset. The proposed antenna is designed and fabricated on a support (polyester; εr=3.2) with a limited volume, i.e., 7×11×46 mm3. The design methods and the measured results of the proposed antenna are presented in detail.

Compact UWB Antenna With I-Shaped Band-Notch Parasitic Element for Laptop Applications

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.

Reconfigurable Beam Steering Using a Microstrip Patch Antenna With a U-Slot for Wearable Fabric Applications

Reconfigurable beam steering using a microstrip patch antenna with a U-slot is proposed for wearable fabric applications. The proposed antenna was manufactured on a fabric substrate and designed to steer the beam directions at the operation frequency of 6.0 GHz. The U-shaped slot and a proximity-coupled feeding technique are applied to design the proposed antenna. By configuring two artificial switches between the proximity-coupled feed and the antenna patch, the antenna is given three beam directions (S0, S1, and S2). The maximum beam directions are steerable in the yz -plane (θ = 0° , 30° , and 331° , respectively), and the overall HPBW is 115°. The measured peak gains are 6.11-6.69 dBi.

Quad-Band Antenna With High Isolation MIMO and Broadband SCS for Broadcasting and Telecommunication Services

The quad-band antenna, which is composed of two compact dual-band antennas, is presented for portable media player (PMP) applications. The antenna for the broadcasting dual band (DVB-H UHF: 470-862 MHz; L: 1452-1492 MHz) is composed of a planar inverted-F antenna (PIFA) with self-complementary structure (SCS) for the broadband performance. The measured operation bandwidth of the antenna (VSWR <; 4) is 500 MHz (370-870 MHz) at UHF band and 220 MHz (1300-1520 MHz) at L band. The two-channel WLAN multiple-input-multiple-output (MIMO) antenna with high isolation performance for the telecommunication dual band (WLAN 11b: 2.4-2.5 GHz; 11a: 5.15-5.825 GHz) is composed of a PIFA operating at 2-GHz band and a loop antenna operating at 5-GHz band. The proposed antennas are fabricated in a PMP case (εr = 3.2 ).

A Compact Frequency-Reconfigurable Multiband LTE MIMO Antenna for Laptop Applications

A compact frequency-reconfigurable multipleinput-multiple-output (MIMO) antenna on a laptop is proposed for multiband LTE services. Each MIMO antenna consists of two planar inverted-F antenna (PIFA) elements, using a T-shaped dc line and two p-i-n diodes (D1 and D2), in conjunction with the proximity-coupled feed structure. By effectively minimizing its dimension and its interference with antenna performance, the proposed T-shaped dc line is designed to fit within the proximity-coupled feed structure. The proposed MIMO antenna covers the LTE 17/13 bands (704-787 MHz, VSWR <; 3) at State 1 (D1 and D2: ON state), and the LTE 20/7 bands (791-862 MHz, 2500-2690 MHz, VSWR <; 3) at State 2 (D1 and D2: OFF state). The proposed antenna obtains high isolation (> 20 dB), low envelope correlation coefficient (ECC <; 0.0161), and total efficiency of greater than 51%, for all operating frequency bands.

Magnetic resonance wireless power transfer using three-coil system with single planar receiver for laptop applications

This paper presents a magnetic resonance wireless power transfer (WPT) system that uses three coils, a planar receiver and operates at 6.78 MHz,. Effective power transfer is ensured by establishing an impedance matching condition for this WPT system. A metamaterial (MTM) array having dimensions of 20 cm X 30 cm is also positioned near the load coil to concentrate the magnetic field and enhance the transfer efficiency. The result is a maximal improvement of 27% in the transfer efficiency at a transfer distance of 50 cm. The impact of a ground plane on the transfer efficiency is also examined. By utilizing the MTM array, making slits on the ground plane and increasing the gap between the ground plane and the load coil, it is possible to mitigate this impact. The highest transfer efficiency improvement is about 55% at a distance of 20 cm with the ground plane. A practical laptop model is fabricated to verify the impact of the load coil angle and position on the transfer efficiency. The result shows that the maximum transfer efficiency with the laptop model is 47.58% with the load coil angle of 90 degree.

A frequency-reconfigurable circularly polarized patch antenna by integrating MEMS switches

A microstrip antenna with integrated RF microelectromechanical system (MEMS) switches is proposed and demonstrated to operate at dual frequencies with circular polarization. The switches are incorporated into the diagonally fed square patch for controlling the operating frequency and a rectangular stub attached to the edge of the patch acts as the perturbation to produce the circular polarization at 6.69 GHz and 7.06 GHz.

Development of RF-MEMS switch on PCB substrates with polyimide planarization

This paper describes an improved manufacturing technology for the fabrication of radio frequency (RF) microelectromechanical systems switches on a laminated printed circuit board (PCB). The process simplifies the fabrication process without sacrificing the RF performance of switches on the PCB. The proposed process patterns a 17.5-/spl mu/m-thick copper layer on the PCB; as a result, the surface becomes highly nonplanarized. Polyimide is then used to planarize the PCBs patterned copper layer. The use of polyimide for planarization has not only made the fabrication process simpler, but it has also reduced the formation of voids in the photoresist sacrificial layer where metallic membrane is deposited and patterned. The switches fabricated with this technology demonstrate a low insertion loss (less than 0.06 dB at 10 GHz) and good isolation (less than 20 dB at 10 GHz).

A single-arm circular spiral antenna with inner/outer feed circuitry for changing polarization and beam characteristics

A single-arm circular spiral antenna has been investigated to get adaptable circular polarization and tilt beam. Circular spiral is printed on a finite size dielectric substrate (/spl epsiv//sub r/=3.27) backed by a finite size-conducting plane. Circular spiral radiates Right Handed Circular Polarization (RHCP) in its inner feed and Left Hand Circular Polarization (LHCP) in its outer feed in one antenna element .Circular spiral has an axial beam (L1=1.64/spl lambda//sub g/) in the z-axis and two-tilted beams (L2=3.25/spl lambda//sub g/, L3=5.55/spl lambda//sub g/) of RHCP in inner feed and LHCP in outer feed at 10GHz, where L is a horizontal arm length. The frequency bandwidth for a 3-dB axial ratio criterion is about 25% in both inner and outer feed at L1=1.64/spl lambda//sub g/.