Abstract
This paper presents low-profile broadband antennas, which are composed of four parasitic patches placed between planar radiators and a perfect electric conductor ground plane. Two types of planar radiators, a conventional dipole and a crossed dipole, are employed to produce linearly polarized (LP) and circularly polarized (CP) radiations, respectively. The radiator and parasitic patches are realized on thin substrates to lower the cost. Owing to the presence of parasitic patches, the antenna performance improves in terms of profile reduction, resonant frequency decrease, and bandwidth enhancement. These improvements are discussed and confirmed computationally and experimentally. The LP design with the overall dimensions of 120 mm × 120 mm × 16.3 mm (0.64λ0 × 0.64λ0 × 0.087λ0 at 1.6 GHz) has a |S11| < −10 dB bandwidth of 1.465–1.740 GHz (17.2%), a broadside gain of 8.5–8.8 dBi, and a radiation efficiency > 96%. The CP design, which has the same physical size as the LP case, has a |S11| < −10 dB bandwidth of 1.388–1.754 GHz (23.3%), a 3 dB AR (axial ratio) bandwidth of 1.450–1.685 GHz (15.0%), a right-hand CP broadside gain of 7.8–8.7 dBic, and a radiation efficiency > 90%.
Highlights
The dipole antenna, which has the simplest configuration, is the most widely used antenna in radio, broadcasting, and wireless communication systems
In order to direct the electromagnetic energy in the desired direction and improve the gain, the dipole antenna is generally equipped with a metallic reflector
This paper investigates low-cost, low-profile broadband antennas, which are composed of four parasitic patches inserted between planar radiators and a ground plane
Summary
The dipole antenna, which has the simplest configuration, is the most widely used antenna in radio, broadcasting, and wireless communication systems. The second method is to place the dipole above an artificial surface [2,3,4,5,6,7,8,9,10] These artificial structures, which are generally composed of a periodic array of metal patches on a grounded dielectric substrate with/without vias, have been designed to mimic a perfect magnetic conductor with a zero-phase shift at certain frequency bands and enable the placement of a dipole having good impedance matching and radiation efficiency in close proximity. A method of inserting a parasitic strip between the horizontal dipole above the ground plane at a low profile (0.05λ0) [11] has been reported to achieve a good broadside radiation with a gain of 7.8 dBi and an efficiency of 74%. These advantages were first computationally determined using the frequency domain ANSYS/ANSOFT high-frequency structure simulator (HFSS) and subsequently confirmed experimentally
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