Abstract
In the paper, a low-profile dual-band printed quadrifilar helix antenna (PQHA) with wide beamwidth is presented for UAV GPS applications. The antenna is composed of a hollow dielectric cylinder with four arms of dual-helix metal strips and a hollow dielectric ring with four pairs of circular metal strips. To provide dual-band operation, different lengths of the dual-helix metal strips are applied. By loading the circular metal strips on the dual-helix metal strips, size reduction of the antenna height is realized. Moreover, wide beamwidth is obtained. A miniaturized quad-feed network is also designed to provide equal amplitude signals with sequentially quadrature phases. To validate the proposed structure, a prototype is fabricated. The height of the antenna is 18.5 mm. The experimental results show that good impedance matching (|S11| <; -18$ dB) and axial ratio (<; 2 dB) are obtained at GPS L1/ L2 bands. At 1.227 GHz, the measured 3-dB axial ratio beamwidths (ARBWs) are 186° and 187° at xoz and yoz planes, respectively. While the values are 167° and 163° at 1.575 GHz. The measured half-power beamwidths (HPBWs) are both more than 120° at the two bands. The results indicate that the proposed PQHA is a good candidate for UAV GPS applications.
Highlights
Unmanned aerial vehicles (UAVs) are widely used for exploration, surveillance, data and multimedia communications, and telemetry applications
To receive signals from GPS orbiting satellites, the GPS antenna is required to have right-hand circular polarization (RHCP) and a uniform mode covering the entire upper hemisphere
It is observed that by using the circular metal strips, the 3-dB axial ratio beamwidths (ARBWs) is enhanced while maintain the same half-power beamwidths (HPBWs)
Summary
Unmanned aerial vehicles (UAVs) are widely used for exploration, surveillance, data and multimedia communications, and telemetry applications. The structure of PQHA is already small, further size reduction is required to meet the space limitations and the high overload for unmanned platform application. A miniaturized dual-band spiral PQHA for UAV application is proposed by surface and inner dielectric loading [20]. The features of wide 3-dB ARBW and high gain at low elevations are often ignored by most of the PQHAs. In the paper, a low-profile dual-band PQHA with wide beamwidth is proposed for GPS L1/L2 applications. A low-profile dual-band PQHA with wide beamwidth is proposed for GPS L1/L2 applications It consists of a hollow dielectric ring and a hollow cylinder with metal strips etched on the external surfaces.
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