Novel Wideband Microstrip Monopole Antenna Designs for WiFi/LTE/WiMax Devices

In this paper, two compact and broadband microstrip monopole antennas have been proposed, designed, and presented using two novel sets of design equations. Each monopole antenna design has different dimension and characteristic. The proposed designs have been verified using a commercial electromagnetic simulator (CST-Studio) and implemented prototypes mounted on FR-4 substrate having a thickness of 1.6 mm. In addition, a linear array consists of only two monopole elements has been designed and presented to enhance the gain of the proposed monopole antenna. Simulation results confirmed the validity of the two novel sets of design equations for both monopole and array antennas. Also, the proposed array antenna (<inline-formula> <tex-math notation="LaTeX">$38\times 36\,\,\text {mm}^{2}$ </tex-math></inline-formula> size), achieved a moderate gain of (6.0 dBi), a satisfying efficiency of (81%), a VSWR that is less than 1.2 and a 22% fractional bandwidth of about 1200 MHz. Moreover, simulated and measured return losses of the proposed monopole antennas (single and array) accomplish a reasonable agreement. The proposed monopole antennas are simple designs and compact in size, and they can be used for many wireless applications including WiFi, LTE, and WiMax. In addition, a compact array of large monopole number can achieve a higher gain that is up to 18 dBi (four to eight monopole array elements with overall size <inline-formula> <tex-math notation="LaTeX">$38\times 72\,\,\text {mm}^{2} \,\,\text {to}\,\,38\times 144\,\,\text {mm}^{2}$ </tex-math></inline-formula>). The novelty of this paper is by introducing the proposed and closed form design equations for a monopole introducing the length of monopole and ground of substrate dimensions as a function of <inline-formula> <tex-math notation="LaTeX">$\epsilon _{r}$ </tex-math></inline-formula> and thickness.