Tuan-Yung Han

A Frequency Reconfigurable Half Annular Ring Slot Antenna Design

The design of a switchable microstrip-fed half annular ring slot antenna for multi-frequency operation is proposed. By incorporating three switches along the meandered tuning stub that is loaded on top of the half circular patch located within the circular slot, easy reconfigurability of four frequency bands over a frequency ratio of approximately 1.7:1 can be achieved. Furthermore, the proposed antenna structure does not require additional DC biasing circuit. Simulation and measurement results have demonstrated that the four frequency bands can exhibit good impedance matching, stable radiation patterns and desirable gains.

Planar Multilateral Disc Monopole Antenna with Variable Band-Notch Function for Bluetooth/UWB Applications

A planar multilateral disc monopole antenna for ultrawideband (UWB) application is initially proposed. By asymmetrically reducing the ground plane structure, this proposed UWB antenna is able to integrate with the Bluetooth band, which provides a wide bandwidth from 2.27 to more than 12 GHz. In order to perform a rejection on the 5.2/5.8 GHz WLAN band signals, the technique of inserting an L-shaped stub into the microstrip feed line is proposed, and with the insertion of another L-shaped stub, a rejection on X-band signals is also achieved. All prototype antennas are theoretically and experimentally investigated, and the vital parameters such as the dimensions of the L-shaped stub for controlling the notched frequency and bandwidth are clearly illustrated. Near omni-directional patterns across the integrated Bluetooth and UWB bands with acceptable gain variation are measured, and good frequency domain characteristics are also observed, except in the notched band.

Circularly polarized annular-ring slot antenna for WiMAX 2.3 GHz and WLAN 2.4 GHz applications

The design of a novel microstrip-line fed circularly polarized (CP) annular-ring slot antenna (ARSA) is studied. To achieve CP radiation with broad axial ratio (AR) bandwidth that can cover both the WiMAX 2.3 GHz and WLAN 2.4 GHz bands, a simple method of loading an inverted L-shaped slot into the bottom section of the ARSA is proposed. Measured results show that the proposed antenna can exhibit wide 10-dB impedance bandwidth of 48% (1.69-2.76 GHz), and its corresponding 3-dB AR bandwidth was approximately 8% (2.29-2.48 GHz).

An aperture-coupled microstrip antenna with frequency agility and polarization diversity

The design of a reconfigurable aperture-coupled microstrip antenna with frequency agility and polarization diversity is proposed. The exchange between the two linear polarizations (vertical and horizontal) at around 2 GHz is achieved by using two PIN-diodes. Furthermore, by allocating a voltage-controlled varactor diode between the radiating element and the ground, a tunable frequency ratio of around 1.17 is achieved on the vertical polarization. When the polarization is switched, good polarization discrimination is also observed.

Compact size annular-ring slot antenna with broad circularly polarized bandwidth

A novel microstrip-line fed circularly polarized (CP) annular-ring slot antenna (ARSA) is investigated. To achieve broad CP bandwidth, a simple method of loading a lightning-shaped slot into the bottom section of the ARSA is proposed. Measured results show that the proposed antenna has wide 10-dB impedance bandwidth of 41.15% (2.20-3.34 GHz), and its corresponding CP bandwidth was approximately 12.94% (2.24-2.55 GHz).

Dual-frequency shorted triangular patch antenna

A single-feed shorted triangular patch antenna that can be operated at two different resonant modes is proposed and studied. The major current distributions of the two modes on the triangular patch are similar to those of a normal triangular patch antenna operated at its TM/sub 11/ and TM/sub 21/ modes. Therefore, the proposed dual-frequency antenna can radiate a conical dipole-like pattern and a broadside pattern at the two resonant frequencies, respectively. In addition, the two operating modes respectively have the 10dB-input-impedance bandwidths of 18 and 9.4%. Details of the antenna designs and obtained results are presented.

A circularly polarized slits loaded UHF RFID antenna with parasitic element

An eccentric annular slot patch antenna is initially studied for UHF (ultrahigh frequency) RFID (radio frequency identification) reader antenna application that can operate within the North America RFID band (902–928 MHz). Circular polarization (CP) radiation is achieved in this band by loading two narrow open-ended slots (slits) into the slot patch. To further enhance the CP bandwidth, a parasitic element is loaded beside the patch antenna that forms the proposed antenna. From the experimental results, the proposed antenna can yield an impedance bandwidth (10-dB return loss) between 618 to 1105 MHz, while good CP bandwidth (3-dB axial ratio, AR) from 886 to 942 MHz is also attained. In addition to that, gain level and efficiency of more than 7.6 dBic and 91%, respectively, were also measured.

An annular-ring slot antenna with CP radiation and harmonic suppression

A microstrip-line fed annular-ring slot antenna with circularly polarized (CP) radiation is initially studied. To achieve harmonic suppression for this antenna, the technique of loading a defected ground structure into the ring slot is proposed. Measured and simulated results show that the proposed antenna can achieve broad CP bandwidth of 9.7% (2.26-2.49 GHz), while good harmonics suppression from 3 to 10 GHz are also demonstrated.

Circularly polarized array antenna with conical beam radiation

A 2 × 2 array antenna with conical beam radiation is proposed. To achieve circular polarization (CP) with broad axial ratio (AR) bandwidth that can cover the WLAN 2.4 GHz band, each array patch element is loaded with a near semi-circular slot fed by an L-shaped probe, which is linked to a corporate feed network. Here, the conical beam radiation with a peak gain at 30 degrees theta (θ) angle is achieved simply by arranging the 4 array patches in a sequentially rotated fashion.

Compact size antenna on thin flexible substrate for WLAN applications

A compact size (20.5 mm × 8 mm) antenna fabricated on a thin flexible substrate with dual-band operation is proposed. To achieve broad enough operating bandwidth to cover the 2.4 and 5.2/5.8 bands for WLAN applications, the proposed dual-band antenna is devised as a quasi-self-complementary (QSC) structure type. From the measured results, both the lower and upper resonant modes have exhibited an impedance bandwidth (2:1 VSWR) of 150 MHz (2390 ~ 2540 MHz) and 840 MHz (5150 ~ 5990 MHz), respectively.