Abstract
This paper presents a novel dual-band circularly polarized patch antenna for precise satellite navigation. The radiation elements are composed of the inner cross-shaped patch and the outer annular patch which are printed on the same surface of one substrate. Two patches work in different bands, respectively, and emit dual-band circularly polarized radiation. In order to obtain a more compact antenna to meet the application of precise satellite navigation, we vertically place four metal cylinders under the ends of the cross-shaped patch to form four capacitive loadings to lower the resonant frequency of the inner cross-shaped patch. A capacitive coupling feed structure is used to match the input impedance of a patch antenna and make the antenna compact enough. The simulated and measured results show that the proposed antenna can produce appropriate dual-band circularly polarized radiation patterns for precise satellite navigation. The measured results of the antenna illustrate that maximum RHCP gain of the antenna is 4.72 dBi in the low band and 3.98 dBi in the high band, the 3 dB gain bandwidth is 70 MHz in the low band and 65 MHz in the high band.
Highlights
Patch antennas are widely used in navigation terminals because of their compact size, low profile, and ease of integration [1]
E challenge of designing a dual-band circularly polarized patch antenna is to achieve both high right-handcircular polarization (RHCP) gain and relatively wide bandwidth in each band. ere are many ways to achieve dual-band operation, and slotted techniques are common by introducing an asymmetric slot in the antenna structure to change the current flowing direction and form two distinct resonant frequency bands
Each patch operates on its own dominant resonant frequency, and the annular patch is used as the radiating element of GPS-L2 band (1.225 GHz), while the cross-shaped patch is considered as the radiating element of GPS-L1 band (1.582 GHz). e parameter c is the gap length between the cross-shaped patch and the metal cylinder
Summary
Patch antennas are widely used in navigation terminals because of their compact size, low profile, and ease of integration [1]. Two eccentric rings and an arc-shaped conducting strip are introduced to achieve the dual-band CP operation [14], but due to the asymmetry of the structure, the axis ratio (AR) is too large, and the problems of low gain and narrow bandwidth cannot be resolved It has been proved by many studies that the RHCP gain of patch antenna or microstrip antenna can be improved effectively by using the capacitive feed method [15,16,17,18,19]. Four metal discs are placed under proposed patches to form capacitive coupling structure to feed the outer annular radiating element and the inner cross-shaped radiating element simultaneously With this new technology mentioned above, the proposed patch antenna has excellent performances such as dual-broadband radiation patterns, high gain, and low back lobe radiation
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