Jui-Han Lu

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.

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.

Single-feed circularly polarized equilateral-triangular microstrip antenna with a tuning stub

Novel circular polarization (CP) designs of single-feed equilateral-triangular microstrip antennas are proposed and experimentally studied. The proposed CP designs can easily be achieved by loading a narrow tuning stub at the triangle tip or at the center of the bottom edge of the triangular patch. Moreover, by embedding a cross-slot of equal slot lengths in the triangular patch, a compact CP operation can easily be obtained, with an antenna size reduction up to about 22%, as compared to the CP design of a regular triangular microstrip antenna without cross-slot at a fixed frequency.

Analysis of slot-coupled double-sided cylindrical microstrip lines

The problem of double-sided cylindrical microstrip lines coupled through a rectangular slot in the common cylindrical ground plane is studied using the reciprocity theorem and a moment-method calculation. Theoretical results of the S-parameters for the slot-coupled cylindrical microstrip lines are calculated and analyzed. Experiments are also conducted to verify the theoretical results.

Characteristics of slot‐coupled double‐sided microstrip lines with various coupling slots

Effects of slot shapes and dimensions on the characteristics of slot-coupled double-sided microstrip lines are investigated. The slot length and end-loading effects are studied for a narrow rectangular coupling slot, and the case of a wide rectangular coupling slot is also analyzed. Results show that the end-loaded slots can improve the coupling between the double-sided microstrip lines. As for a narrow rectangular slot, optimal coupling can be obtained when the coupling slot is about at resonance, and the coupling increases when the slot width increases. Details of the results are presented and discussed.

Slot-coupled directional couplers between double-sided cylindrical microstrip lines

Slot-coupled directional couplers between double-sided substrate microstrip lines have found applications in the design of many important circuits. To analyze the characteristics of such slot-coupled directional couplers on a curved surface, we present the study of slot-coupled double-sided cylindrical microstrip lines. The inside and outside cylindrical microstrip lines are coupled through a rectangular coupling slot in the common cylindrical ground plane. To solve the problem a full-wave approach incorporating a Galerkins moment-method calculation is applied. The S parameters of such a directional coupler are calculated and compared with experiment.

STUDIES OF SLOT-COUPLED DOUBLE-SIDED PERPENDICULAR MICROSTRIP LINES

The double-sided perpendicular microstrip lines coupled through an arbitrarily inclined narrow rectangular slot in the common ground plane are studied by applying the reciprocity theorem and by using the exact Greens functions for the structure in a moment-method calculation for the unknown slot electric fields. The S parameters of the slot-coupled perpendicular microstrip lines are formulated and calculated, and theoretical results are verified with measurements. The effects of the inclination angle and length of the coupling slot on the electromagnetic coupling between the slot-coupled perpendicular microstrip lines are also studied.