A Broadband Omni-directional Small Printed Antenna Comprising Symmetrically Arranged Trapezoid Elements

The demand for small wireless telecommunications modules that can access the IMT system has increased and their use has proliferated to the remote control of applications such as controlling stock and verifying purchases for vending machines, managing taxi operations, reading of meters, and managing delivery trucks. The IMT system mainly uses the 800 MHz to 2 GHz frequency band. We focus on actualizing an antenna for a small wireless telecommunications module that can operate in the 800 MHz band because utilizing this band poses difficulties in terms of miniaturization and securing the gain. This paper proposes a new small broadband printed antenna that achieves a fractional bandwidth of 28.9% with the size of 0.160λ×0.226λ (@lowest frequency). This antenna is suitable for mass production and is cost efficient due to its printed antenna structure. Its omni-directional pattern allows a wide range of placement possibilities. The rest of the paper is organized as follows. First, the proposed antenna structure is described in Section 2. The center frequency and bandwidth characteristics are investigated based on the method of moment (MoM) simulation and measurement, and the optimum antenna structure parameters that satisfy a low operating frequency with a wide bandwidth are clarified in Section 3.1. Finally, the current distribution and radiation pattern characteristics are presented in Section 3.2.