EQUIVALENT CIRCUIT MODEL

A circuit model describing the antenna’s operation (see Figure 14a) provides insight into its construction. It is created by fitting the simulated S-parameters to an ADS software circuit model. A comparison of the |S11| of the circuit model with the HFSS simulation is shown in Figure 14b.

Figure 14

Figure 14 Final antenna equivalent circuit model (a) and |S11| from the circuit model vs. HFSS simulation (b).

CONCLUSION

A wideband microstrip patch antenna providing both linear and circular polarization was designed to cover multiple wireless applications. To determine the resonant frequency of the conventional hexagonal microstrip patch antenna, theoretical calculations with many combinations of side lengths of the regular hexagonal patch were performed. Three slits were added to the radiating patch to enhance its impedance bandwidth, and the patch was shorted to ground with a copper pin, which changes a portion of the radiating band from linear to circular polarization. The final design achieved an impedance bandwidth of 42.4 percent, from 2.4 to 3.69 GHz as defined by |S11| ≤ -10 dB.

The antenna serves applications requiring a small antenna (47 × 40 × 6 mm3) and a low manufacturing cost, such as Wi-Fi (2.4 to 2.485 GHz), Bluetooth (2.4 to 2.5 GHz), cellular (3.2 to 3.3 GHz), WiMAX (2.5 to 2.69, 3.3 to 2.4 and 3.4 to 3.69 GHz), military radar (2.7 to 2.9 GHz) and radar and navigation (2.9 to 3.1 GHz).

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