Myun-Joo Park

A Dual-Band Wilkinson Power Divider

A new scheme is proposed for the dual-band operation of the Wilkinson power divider/combiner. The dual band operation is achieved by attaching two central transmission line stubs to the conventional Wilkinson divider. It has simple structure and is suitable for distributed circuit implementation.

Dual-band, cross coupled branch line coupler

A novel branch line coupler structure is proposed with application to the dual band operation. The proposed structure has additional cross coupling branches to the conventional branch hybrid coupler. Additional design freedom can be obtained using the proposed scheme, which can serve many useful purposes such as the dual band operation of the branch line coupler.

Dual-Band Wilkinson Divider With Coupled Output Port Extensions

A new Wilkinson power divider structure is proposed for the dual-band operation. The proposed divider has two output ports extended and coupled through a coupled line section. The use of coupled output port extensions eliminates the need of the input port extension for the dual-band operation and simplifies the overall divider structure. It also provides the improved frequency performance over a wide range of band ratios with practical design parameters and has some potential for the broadband operation for small band ratios.

Two-Section Cascaded Coupled Line Wilkinson Power Divider for Dual-Band Applications

A coupled line based design method is presented for the dual-band operation of the Wilkinson power divider. It is shown that a simple two-section cascaded coupled line structure is capable of the dual-band operation in the Wilkinson power divider. The overall divider structure can be simplified with the small number of transmission line sections and the coupled line using the proposed approach.

Dual-Band Branch-Line Coupler With Port Extensions

A new branch-line coupler structure with port extensions is proposed for the dual-band operation. The conventional branch-line coupler structure is adapted to the dual-band operation by inserting a transmission line section at the input ports and modifying the branch parameters. The dual-band performance of the proposed coupler is verified theoretically through the rigorous microwave circuit analysis and the exact design equations are derived in concise form. The design, simulation, and measurement results validate the dual-band capability of the proposed coupler with the same quadrature phase relation between the two band frequencies.

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.

Dual-Band, Unequal Length Branch-Line Coupler With Center-Tapped Stubs

A new dual-band branch-line coupler scheme is proposed based on the unequal length branch-line coupler structure and the center-tapped stub lines. The unequal length structure reduces the size of the dual-band branch-line coupler using center tapped stubs. Also, it offers the possibility of the stubless dual-band operation for some special cases, and the same phase relation can be obtained between the two output signals at the two frequency bands.

Stubbed Branch Line Balun

A new impedance transforming balun scheme is presented based on the branch line structure with stubs on the vertical branches. The stubbed vertical branch eliminates the unwanted even mode output and provides only the required balun output with opposite phase. Also, the use of stubs reduces the branch lengths by two times the stub length and therefore, helps to reduce the total size of the proposed balun

Ku-band high efficiency antenna with corporate-series-fed microstrip array

Excellent efficiency of a linearly polarized microstrip array in Ku-band is achieved by having proper impedance matching throughout the array and by properly using the corporate and series fed by microstrip transmission lines. The cavity-backed microstrip patch is used to obtain relatively wide bandwidth. The auto-tracking Ku-band antenna in the azimuth direction has developed with a very low profile for vehicles rooftop mounting, as well as, a low manufacturing cost. The main beam of array is tilted 15/spl deg/ away from the broadside direction to provide optimum coverage for Korea satellite III.

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.