Mesh-Grounded Monopolar Hexagonal Microstrip Antenna for Artillery-Launched Observation Round

Abstract

This paper presents a novel low-profile microstrip antenna with an omnidirectional radiation pattern for an artillery-launched observation round. The proposed antenna consists of one centered hexagonal patch for a feeding network and six periodic arrays of a trapezoid patch for a radiator. The trapezoid patch is equal to a half-sized hexagonal patch based on geometrical symmetry. A gap-coupled one-hexagonal patch and six trapezoid patches are supported on a nonfundamental TM02 mode for vertically polarized omnidirectional radiation patterns. In addition, a meshed ground structure for the proposed antenna is employed to improve the impedance bandwidth. The thin metal wires that are formed by the meshed ground structure yield six trapezoid slot arrays for the feeding network and three triangular slot arrays for the radiator on the ground plane. To verify the feasibility of the meshed ground structure, the mesh width, denoted by w, was investigated theoretically and optimized carefully to enlarge the impedance bandwidth of the proposed antenna. Finally, the proposed antenna, with a mesh width of 0.2 mm, successfully demonstrated excellent monopolar radiation at a resonant frequency of 5.84 GHz, a realized gain of 5.27 dBi, and an impedance bandwidth of 452 MHz from 5.583 GHz to 6.035 GHz with respect to 7.78% at a center frequency of 5.809 GHz.

Extremely Low-Profile Monopolar Microstrip Antenna with Wide Bandwidth

“…Figure 1 displays the configuration of the proposed antenna. As addressed in the Introduction section, the whole antenna geometry and denoted antenna design parameters are almost identical compared to [ 31 ] in our previous research result. In this study, we only deal with the degenerated TM 02 modes in this work.…”

“…In this study, we only deal with the degenerated TM 02 modes in this work. The variables of the proposed antenna are kept almost equally compared with [ 31 ] and its description is shown in Table 1 . As shown in Figure 1 , the proposed antenna has a gray-color dotted center feeding patch, which is directly connected through a 50-Ohm commercial coaxial line and six black-color dotted radiating patches that are electromagnetically coupled with physical metal to metal gap capacitance.…”

“…Figure 3 illustrates the simulated electric field distributions for understanding the dual resonant phenomenon, that is, the operation principle of the proposed antenna. As mentioned in the previous section, we used a monopolar microstrip antenna as a validated model in [ 31 ]. The omni-directional radiation is realized by utilizing the non-fundamental 1.5-wavelength resonant TM 02 mode like the conventional monopolar microstrip antenna.…”

“…This method may show a disadvantage in that a single resonant mode supports only a single operation bandwidth, the thickness of the substrate is thick and the bandwidth is relatively narrow. And to overcome the narrow bandwidth issues, a design method of adding a slit and through-hole vias on the radiator [ 7 , 10 , 31 , 32 , 33 ], stacking multi-layered substrates for multiple resonance modes [ 9 ] and adding stubs in same substrate layer for degenerated mode with adjunct frequency with 90-degree phase delay [ 33 , 34 , 35 , 36 , 37 , 38 ]. Unfortunately, these technologies can have improved bandwidth, but the thickness of the antenna dielectric substrate is still thick, and the design method is complicated.…”

“…In other words, the proposed antenna can provide a wide bandwidth with a simple design and a thin thickness by using the degenerated mode of a single resonator on a single substrate. To verify this new physical phenomenon, that is, the degenerated TM 02 modes, we designed the proposed antenna based on the verified antenna model previously presented in [ 31 ]. In addition, the parametric studies of the proposed antenna were investigated and optimized to control the degenerated modes of the proposed antenna.…”