Design of a Dual Patch Triangular Microstrip Antenna

This paper investigates the design, measurement and characteristics of a probe-fed dual patch equilateral triangular antenna. A lossless foam material is sandwiched between the two patches to provide a mechanically stable and uniform height. It is shown that the separation height between the two patches plays a significant role in improving the impedance bandwidth of the antenna. A bandwidth of 13.2 percent is measured around a center frequency of 2.50 GHz. Measurements on gain and polar patterns are also presented. This antenna could find useful applications in the industrial, scientific and medical (ISM) frequency bands. During the last two decades, a considerable number of papers have been published on the performance and applications of microstrip patch antennas [1-4]. Various patch configurations such as annular-ring, disk, rectangular and triangular have been investigated. These patch antennas possess many desirable features, such as low profile, light weight, low cost, direct integrability with microwave circuitry and the ability to conform to the surface of a host object. Such features make microstrip patch antennas useful for many applications in radar and wireless communication systems. However, one of the principal limitations of such antennas is their very narrow bandwidth, which is on the order of a few percent. Many bandwidth enhancement techniques have been suggested and implemented in recent years, and one such technique is stacking patches either horizontally or vertically [5-7]. In this paper, we present an experimental investigation on broadbanding the impedance bandwidth of a vertically stacked equilateral triangular patch antenna. The equilateral triangular patch configuration is chosen because it has the advantage of occupying less metalized area on the substrate than other existing configurations. A lossless foam material is used to control the distance between the two patches and to provide a mechanically stable height separation. In practice, it was found that the height separation plays a significant role in achieving the optimum impedance bandwidth of the antenna. The described antenna has an impedance bandwidth of 13.2 percent with the two ends of the frequency band being at 2.43 GHz and 2.76 GHz respectively. Measurements of antenna gain and radiation patterns are also presented.