In-Bok Kim

Design of Compact and Broadband Quasi-Yagi Antenna Using Balance Analysis of the Balun

In this paper, a compact, broadband quasi-Yagi antenna utilizing balance analysis of the ultra-wideband microstrip-to-coplanar stripline(MS-to-CPS) balun is proposed. The antenna size was reduced by removing the reflector on bottom layer and ground plane is used as a reflector. A planar balun that transforms from microstrip(MS) to balanced coplanar stripline(CPS) is characterized in the amplitude and phase imbalances at CPS output ports are investigated and discussed. As compared with the conventional balun, the proposed MS-to-CPS balun demonstrated very wideband performance from 7 to over 20 GHz. From the simulation study, amplitude and phase imbalances are within 1 dB and , respectively. The implemented antenna provides very wide bandwidth from 6.9 to 15.1 GHz(74.5 %). The gain of the antenna is from 3.7 to 5.5 dBi, the front-to-back ratio is more than 10 dB, and the nominal radiation efficiency is about 94 %.

Design of Wideband Bow-Tie Antenna with Folded-Slit Band-Notch Structure

A wideband bow-tie antenna fed by wideband microstrip-coplanar stripline(CPS) balun and band notch structures that can be applied to bow-tie antenna are proposed in this paper. In order to increase bandwidth, bow-tie radiators are reshaped so that the surface current flows continuously, and wideband impedance matching is achieved by adjusting strip width and spacing of CPS feeding line. The VSWR is measured as 2:1 over the wide frequency range of 2.3~12 GHz. The fabricated antenna size is 60 mm×60 mm. In order to achieve the band-notch function at WLAN(5.8 GHz), λ/4 folded-slits located λ/4 away from feeding point are utilized. To minimize the slit size, folded-slit type is adopted. The measured VSWR is 7:1 and gain attenuation is 14 dB at 5.8 GHz.

A Multi-Band Antenna on Automobile-Glass Using Flexible PCB

In this paper, we propose a multi-band monopole antenna with a band-notching U-slot, which is fabricated inside the flexible polymide film substrate. The U-shaped slot located on the patch-shaped monopole antenna provides band-notch at 2.7 GHz, but also helps to improve return loss at adjacent frequency bands. The performance of the antenna attached on an automobile-glass has been simulated and measured. The fabricated antenna provides more than 10 dB return loss for ISM band(2.4~2.483 GHz) and WAVE band(5.85~5.925 GHz), 2.8~5.7 dBi maximum gain, and good radiation patterns.

Ultra-wideband components using a microstrip-to-CPS balun

Various types of ultra-wideband components with 10s of GHz bandwidth have been developed utilizing a uniplanar ultra-wideband balun, which is a simple microstrip-to-coplanar stripline (CPS) transition structure with the operating frequency range from near DC to over 40 GHz. Developed ultra-wideband components include antennas, mixers, doublers and detectors in a carrier type or in a surface mountable type. These high-performance, low-cost ultra-wideband components may replace expensive conventional components, and also can be used to develop new multi-GHz UWB application areas.

Keynote address VI A new ultra-wideband balun and its associated components

A recently developed ultra-wideband (UWB) balun opens new possibilities for the low-cost, mass-producible, and surface mountable UWB components with 10psilas of GHz bandwidth. The balun is a simple microstrip-to-coplanar stripline transition structure, but a single balun can be designed to have operating frequency range from DC to over 40 GHz. The balun design is based on optimal impedance matching and smooth field transformations between adjacent transmission lines. Utilizing this uniplanar balun, new low-cost and mass-producible components-e.g., mixers, doublers, antennas, detectors, differential amplifiers, etc.-with 10psilas of GHz bandwidth are being developed. The new UWB components can also be designed in the form of low-cost surface-mountable chips, which may open new commercial UWB application areas. In this presentation, the design of the ultra-wideband balun will be described, and recent developments of new UWB components utilizing the balun will also be introduced.

Wideband Microstrip Conformal Patch Array Antenna with Tilted Beam

In this paper, a conformal type 1×4 microstrip patch array antenna with tilted antenna beam is presented for UWB sensor applications. Each antenna element comprises E-shaped patch with L-probe feeding to increase the bandwidth. The tilted antenna beam of 20 degree can be achieved with 42 ps microstrip delay lines at the series feeding network with T-junctions. The measured reflection coefficient is >9 dB at 3.5~4.5 GHz. The measured antenna gain and HPBW are >10 dBi and <30 degree at 3.75~4.25 GHz.

A wideband bow-tie antenna using suspended stripline balun

In this paper, the design of a wideband bow-tie antenna using suspended stripline (SSL) balun is presented. The utilized balun is composed of a wideband multi-section power divider and a left-handed nonlinear transmission line (LH NLTL) implemented with SSL. The fabricated balun exhibits wide frequency bandwidth form 4 to 18GHz (127%). To demonstrate applicability of the proposed balun, a modified bow-tie antenna is built and tested. The fabricated antenna provides wide frequency bandwidth from 5 to 18GHz (110%) and the measured gain of typical 3.5 dBi with quasiomni directional radiation patterns.

Reduction of Electromagnetic Interference between the LCD Driving Module and WWAN Antennas

In this paper, we analyzed the RF interactions between WWAN antennas and an LCD driving module inside the cover of a notebook computer, and discussed reduction method of RF coupling. In order to simulate the RF noise source from the LCD driving module, a multi-band antenna was designed and used with a simplified notebook model to test the RF coupling phenomena. We verified that the RF noise coupling is enhanced at certain frequencies due to cavity structure formed inside the notebook computer. Also, we showed that conductive barrier walls, which are inserted inside the notebook, could be effective in reducing RF coupling.

Suspended Stripline Filter Design Using a New Ultra-Wideband Microstrip-to-Suspended Stripline Transition

In this paper, a novel ultra-wideband microstrip-to-suspended stripline(SSL) transition is proposed, and SSL filters with low-loss and high selectivity have been realized using this transition. Since the proposed transition has low-loss and wide bandwidth characteristic, the design procedure of SSL filters become simplified. Additionally, the designed filters do not require extra time-consuming tuning. As design examples, SSL low-pass and high-pass filters have been implemented, and a implemented bandpass filter with connection of the low and high-pass filters performs 2.3~10.5 GHz bandwidth with less than 1.2 dB insertion loss and high selectivity.

Design of a Band-Tunable Ultra-Wideband Single-Balanced Doubler

In this paper, design and the implementation method of a band-tunable ultra-wideband planar doubler are described Microstrip-to-CPS(balun) transition and Microstrip-to-CPW transition are respectively used for input/output matching circuits for the doubler. The Input balun structure allows to apply diode bias, and the doubler output frequency is tunable by changing the diode bias voltage. With the bias voltage of -0.6 V, the measured operating frequency band of the implemented doubler is GHz, with the bias voltage of V, the operating frequency band is GHz, and with 0 V bias, the operating frequency band is GHz. The doubler provides conversion loss of less than 15 dB and fundamental frequency suppression of 30 dB.