A low‐profile dual‐mode antenna for unmanned aerial vehicles applications

Abstract

Abstract A low‐profile dual‐mode antenna is proposed in this paper. The antenna is composed of a semi‐rectangular‐annular (SRA) coaxial line with sleeve loading structures vertically mounted on the ground plane. The proposed antenna has two radiation modes, mode 1 of the vertically polarised (VP) radiation characteristics at 500 MHz and mode 2 of the horizontally polarised (HP) radiation characteristics at 588 MHz. The two vertical components of the SRA coaxial line contribute to the VP radiation, which is achieved with the in‐phase electric currents on the two vertical components by adjusting the length of the in‐body inductive loading structures. The horizontal component of the SRA coaxial line is mainly contributed to HP radiation when the electric currents on two vertical components are reversed. And the antenna is well matched with the additional impedance matching network, which consists of two inductors and a capacitor. The height of the fabricated prototype is only 25.9 mm (about 0.04λ) at 500 MHz. The fabricated prototype possesses monopole‐like radiation pattern at 500 MHz and loop‐antenna‐like radiation pattern at 588 MHz. The measured maximum gain of the proposed antenna at 500 MHz is −6.8 dBi, and the measured maximum gain of the proposed antenna at 588 MHz is 2.5 dBi. The antenna is suitable for unmanned aerial vehicles communication systems due to its advantages of low‐profile and dual‐mode radiation.

Keywords

• dual‐mode antenna
• low‐profile antenna
• unmanned aerial vehicles (UAVs)