Chia-Luan Tang

Single-feed slotted equilateral-triangular microstrip antenna for circular polarization

Novel designs of single-feed equilateral-triangular microstrip antennas for circular polarization (CP) are proposed and studied experimentally. It is demonstrated that by embedding a narrow slot or a cross slot of unequal slot lengths in the triangular patch, circularly polarized radiation of microstrip antennas can easily be achieved using a single probe feed. Furthermore, results show that for the design with a cross slot, the proposed antenna can perform CP radiation with a reduced antenna size at a given frequency (denoted as compact CP operation here); that is, the required antenna size is smaller for the proposed antenna for performing CP radiation as compared to a conventional circularly polarized triangular microstrip antenna at a fixed operating frequency. Details of the proposed CP designs are described, and typical experimental results are presented and discussed.

A compact meandered circular microstrip antenna with a shorting pin

By using a shorting pin and meandering the circular patch, a compact circular microstrip antenna with a patch size of less than 10% of the conventional circular patch antenna can be easily obtained. The design of such compact circular microstrip antennas is described, and experimental results are presented and discussed.

Novel dual-frequency and broad-band designs of slot-loaded equilateral triangular microstrip antennas

By loading properly arranged slots in an equilateral-triangular microstrip patch, novel dual-frequency and broad-band operations of a single-feed triangular microstrip antenna are presented. For dual-frequency operation, the proposed design is achieved by loading two pairs of narrow slots in the triangular patch, one embedded close to the side edges of the patch and the other inserted at the bottom edge of the patch. The obtained two operating frequencies are of same polarization planes and by varying the positions and lengths of the inserted slots at the bottom edge of the patch, a tunable frequency ratio of the two frequencies ranging from about 1.16 to 2.06 is obtained. Furthermore, it is found that by protruding a narrow slot out of the embedded slots close to the side edges, broad-band operation of the triangular microstrip antenna near its fundamental resonant mode can be achieved. Results show that the antenna bandwidth of the proposed broad-band design can be greater than 2.6 times that of a conventional triangular microstrip antenna. Details of the proposed dual-frequency and broad-band designs are described and typical experimental results are presented and discussed.

Broadband probe-fed patch antenna with a W-shaped ground plane

A new design of a broadband probe-fed patch antenna with a W-shaped ground plane is presented. The W-shaped ground plane is obtained by bending the conventional planar ground plane into an inverted V-shape, seen in the resonant direction of the patch antenna and then adding proper flanges at the two straight edges of the bent ground plane. The proposed design is applicable to the patch antenna with a planar radiating patch with a thin air substrate. With the use of the proposed W-shaped ground plane, the required probe-pin length in the substrate remains small, although the effective substrate thickness is significantly increased, resulting in a much wider operating bandwidth. Also, by choosing proper dimensions of the W-shaped ground plane, the antenna gain for frequencies over the obtained wide bandwidth is enhanced, compared to the conventional patch antenna with a planar ground plane. In addition, the cross polarization is also reduced for the proposed design and the cross-polarization level (XPL) in the H-plane pattern can even be better than that of a conventional probe-fed patch antenna with a thin air substrate.

A broadband planar patch antenna fed by a short probe feed

This paper presents a novel design of a broadband probe-fed planar patch antenna. The proposed antenna has a thick air-layer substrate, and bandwidth enhancement is achieved by cutting a small portion of the ground plane and adding an inverted U-shaped ground plane to be close to the radiating patch, and then feeding the antenna at the inverted U-shaped ground-plane portion using a 50-/spl Omega/ coax feed with a short probe pin. Prototypes have been successfully implemented, and experimental results show that an impedance bandwidth (1:1.5 VSWR) greater than 20% can be achieved for the proposed antenna. Radiation characteristics of a prototype suitable for application in a DCS cellular system (1710-1880 MHz) base station are also presented.

Optimized isolation between internal antennas for a dual-network wireless device

Experimental and simulation studies for achieving optimized isolation between two internal UMTS and WLAN antennas for a dual-network wireless device are presented. Results indicate that the isolation of the two antennas is strongly affected by their relative position, and that isolation less than -30 dB is possible for the two antennas. It has also been observed that the isolation is strongly related to the excited surface current distributions in the system ground plane of the wireless device.