Byoungchul Kim

Multiband Dual Spiral Stripline-Loaded Monopole Antenna

We propose a multiband antenna that exhibits a dual coupling characteristic and dual frequency operation using a dual spiral stripline-loaded monopole in conjunction with L-shaped slots in a ground plane. The slots allow the upper part of the ground plane to function as an additional monopole that resonates in concordance with the existing resonances of the upper and lower spiral stripline monopoles. As a result, the impedance band- widths are greatly enhanced while maintaining relatively good omnidirectional radiation characteristics. The proposed antenna occupies a volume of 36 times 7 times 102 mm3 including the ground plane, and the measured impedance bandwidths with VSWR < 2 simultaneously cover CDMA, GSM900, DCS1800, PCS1900, UMTS, IMT-2000, and WiMAX2350 bands. We describe the detailed antenna structure and present measurement results.

Slot-line-fed quasi-Yagi antenna

This paper presents a broadband slot-line-fed quasi-Yagi antenna. The gap size of the coplanar stripline was designed in a staircase shape to improve the impedance matching between and the feed line and the antenna. The antenna has a broad bandwidth of approximately 55% (4–7 GHz with a reflection coefficient of less than −10 dB). The radiation pattern is very good and the antenna exhibits a flat gain of 4.9–5.6 dBi within the impedance matching bandwidth.

Effects of ground plane size on a square microstrip patch antenna designed on a low-permittivity substrate with an air gap

The effects of ground plane size on the characteristics of a square microstrip patch antenna designed on a low-permittivity substrate with an air gap were investigated. The characteristics studied include return loss, gain, halfpower beamwidth (HPBW), and radiation pattern. The gain and HPBW varied periodically with increasing ground plane size, and were out of phase with each other. The relationship of the above parameters with the height of the antenna was also considered. Decreasing the antenna height changed the smallest ground plane size for impedance matching, and also reduced back radiation, which improved the front-to-back level of the microstrip patch antenna.

Design of Broadband Quasi-Yagi Antenna Using a Folded Dipole Driver

This paper describes the development of a broadband quasi-Yagi antenna using a folded dipole driver. The antenna is designed on a low-permittivity substrate to reduce the surface wave effect, and hence the gain can be enhanced easily by adding directors. The folded dipole driver is connected to a 50-Ω microstripline via a simple broadband microstrip-to-coplanar stripline transition with a quarter radial stub. The key motivation for the use of a folded dipole is to increase the input impedance at the driver, allowing a smaller mismatch loss between the antenna driver and the coplanar stripline feed. The proposed antenna has a measured bandwidth of 4.67～6.26 ㎓ for the ?10 ㏈ reflection coefficient, and a flat gain of 4.86～5.15 ㏈ within the bandwidth.

Effects of a cavity structure on a half E-shaped microstrip patch antenna

The effects of a cavity structure on the characteristics of a half E-shaped patch antenna printed on a low-permittivity substrate with an air gap were investigated. The addition of the cavity structure increased the impedance bandwidth, improved the gain, and reduced the backward radiation of the antenna.

Design of Cavity-Backed High Gain Dual Band Microstrip Antenna Using Frequency Selective Surface

In this paper, a cavity-backed high gain dual band microstrip antenna with Frequency Selective Surface space(FSS) for WLAN is proposed. The proposed antenna that operates in IEEE 802.11a/b bands with similar radiation pattern and gain is fabricated on RO4003 substrate with a dielectric constant of 3.38. The size of the antenna is , and the FSS size is . The ground plane size including cavity is . The antenna is fed by coaxial cable. The simulated bandwidths of the antenna are 2.369~2.517 GHz and 5.608~5.833 GHz for VSWR

A Dual Baud Microstrip Antenna with Soft Surface for Gapfiller Applications

In this paper, a dual band microstrip antenna with soft surface for gapfiller applications is proposed. The proposed antenna with similar radiation pattern and gain is fabricated on RO4003 substrate with a dielectric constant of 3.38 and a thickness of 0.508 mm, and operates in IEEE 802.11a/b bands. The size of the antenna is and the ground plane size including soft surface structure is . The antenna is fed by coaxial cable. The simulated bandwidths of the antenna are 2.388~2.493 GHz and 5.561~6.051 GHz for VSWR

Design of a Dual Spiral Line Loaded Monopole Antenna for Cellular and RFID Bands

We have presented a dual spiral line loaded monopole antenna on a vertical ground plane. The antenna has a 152 MHz impedance bandwidth (820 ~ 972 MHz) for VSWR<2 at a central frequency of 896 MHz. The proposed antenna covers both the cellular and UHF RFID bands in Korea and is suitable as the internal antenna of a handheld transceiver unit because of its thin configuration, broad bandwidth, and good omnidirectional radiation characteristics.

A Dual-Sprial Line Loaded Monopole Antenna having a Vertical Groundplane for Quadband Applications

In this paper, we propose a dual-spiral line loaded monopole antenna having a vertical ground plane for quadband applications. The antenna occupies a volume of with a ground plane. The measured impedance bandwidths of the antenna based on are approximately of 11.7 % and 24.8 % in the first and second frequency band, respectively. The operating frequency can simultaneously cover Cellular(), PCS(), UMTS(), and IMT-2000() bands. The maximum gains of the antenna are -0.99 dBi, 4.07 dBi, 2.72 dBi, and 4.33 dBi at the center frequencies of the Cellular, PCS, UMTS, and IMT-2000 bands, respectively. Good radiation patterns are experimentally obtained.

A Dual Band Microstrip Antenna with Two Y-Shaped Slots for Satellite Internet Service

In this paper, a dual band microstrip antenna with similar radiation pattern for the satellite internet service is proposed. The proposed antenna has two Y-shaped slots on the microstrip patch that is fabricated on RO4003 substrate with a dielectric constant of 3.38 and a thickness of 0.508 mm, and operates in the 2 GHz and 5 GHz bands. The size of the antenna is , and fed by coaxial cable. The measured bandwidths of the antenna are 2.3982.507 GHz and 5.4585.972 GHz for VSWR