Dual‐frequency rectangular microstrip antenna with an inserted integrated reactive loading

Abstract

A no¨el dual-frequency rectangular microstrip antenna with an inserted integrated reacti¨e loading is proposed and experimentally studied. The reacti¨e loading has the structure of a trapezoid microstrip-line section inserted at one of the radiating edges of the patch. By adjusting the flare angle of the trapezoid microstrip-line section, the frequency ratio of the two operating frequencies is tunable in the range INTRODUCTIONDual-frequency design for a rectangular microstrip antenna with an inserted short-circuited microstrip-line section at one w x of the radiating edges of the patch has been presented 1 . In such a design, the inserted short-circuited microstrip-line section serves as an integrated reactive loading to the mi- Figure 1 Geometry of a dual-frequency rectangular microstrip antenna with an inserted integrated reactive loading crostrip antenna. By selecting the length of the inserted short-circuited microstrip-line section, two resonant modes near the fundamental mode of the original unloaded microstrip antenna can be excited. However, because the inserted short-circuited microstrip-line section protrudes beyond the patch edge, the real size of this antenna is larger than that of the original unloaded microstrip antenna. Recently, dual-frequency operation of a single-feed rectangular microstrip antenna with an embedded reactive loading was w x also reported 2 . In such a case, the inserted short-circuited microstrip-line section is replaced by a microstrip structure of two cascaded microstrip-line sections embedded within a rectangular slot cut in the rectangular microstrip patch. The two cascaded microstrip-line sections also provide an intew x grated reactive loading to the microstrip antenna 3᎐5 . Moreover, because the embedded reactive loading requires no protrusions beyond the patch boundary, this design is w x more compact than that reported in 1 . In this letter, we report a new and promising design of a rectangular microstrip antenna with an inserted integrated reactive loading for dual-frequency operation. The inserted integrated reactive loading has the structure of a trapezoid microstrip-line section having a flare angle ␣ subtended by its two parallel sides, which can be easily constructed by inserting two narrow Ž . slits at one of the radiating edges of the patch see Fig. 1 . Since the inserted integrated reactive loading also requires no protrusions beyond the patch boundary, the proposed antenna has the same compact characteristic as the dualw x frequency design reported in 2 , but is simpler in structure. For the two operating frequencies of the proposed antenna, the same polarization planes and broadside radiation patterns are obtained. By using a trapezoid microstrip-line section of various flare angles, the frequency ratio of the two operating frequencies can also be adjusted. Details of the proposed antenna and experimental results are presented. Figure 1 shows the geometry of a dual-frequency rectangular microstrip antenna with an inserted integrated reactive loading....

High Gain Rectangular Broad Band Microstrip Antenna With Embedded Negative Capacitor and Chip Resistor

“…For a desired radiation pattern from a loading antenna, the loading voltages have to maintain essentially certain values of magnitude and phase. Therefore, it is desirable to design a loading network to yield a specified radiation [7]. In the past years a great deal of interest has been shown in the development of microstrip antennas [8,10,11,13,14,16].…”

“…In this respect, microstrip antennas have narrow beam width and low gain because of their heavy reactances. During the past ten years, numerous researchers have published reactive loaded antennas for improving the antenna performances [7,10,15,17,18]. The radiation efficiency decreases depending on the geometry.…”