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In this letter, a high-gain circularly polarized (CP) array antenna with low profile and low grating lobe property is proposed. The array is composed of high-gain and low sidelobe CP patch elements based on odd high-order modes. By adding perturbation structure, a pair of orthogonal modes (TM30/TM03) of the patch with 90° phase difference is diagonally excited. Meanwhile, by introducing five circular slots on the patch, four sidelobes of the element radiation pattern in x o z plane and y o z plane are effectively reduced. Consequently, the large grating lobes of array antenna can be avoided. Then, a 2 × 2 array prototype is designed and fabricated for verification. The thickness of array is only 0.5 mm (0.027 λ 0). The peak gain and aperture efficiency reach up to 17.5 dBic and 55.5%, respectively. When the element spacing is more than 1 λ 0, the measured maximum grating lobe level at 16.25 GHz is only −15 dB.

In this paper, a high gain array antenna based on odd higher order mode is proposed. Different from traditional microstrip array antennas, elements of this array are square patches of resonating at TM 30 mode with large side lobes. In order to avoid the influence of the element side lobes on the directivity of array antenna, by controlling the array element spacing and number, the grating lobes of array factor can avoid the element side lobes and coincide with the null region of element pattern, which allows the TM 30 mode can be used in array antenna designs. Simulated results show that the gain of the 8-element array antenna is 19.5dBi and the grating lobes level are lower than −15dB.

In this letter, a high-isolation dual-polarization microstrip patch antenna with omnidirectional radiation patterns is proposed. The radiation elements of the antenna are a combination of an annular-ring patch and four curved branches. The annular-ring patch is fed by a modified capacitive coupling structure to radiate a vertically polarized omnidirectional pattern, while the four curved branches that are set around the annular-ring patch with a suitable distance for high isolation are fed in phase to radiate a good horizontally polarized omnidirectonal radiation pattern. The isolation between the two ports is better than a high degree of - 40 dB to limit the interference of the signals. A prototype of the proposed antenna is fabricated and measured to verify the predictions, and the measured results are in good agreement with the simulated ones. The proposed antenna is a good candidate for wireless communication for its extremely low profile, high port isolation, and omnidirectional radiation property.

In the references of the above letter (ibid., vol. 11, pp.1273-1276, 2012), a mistake was made regarding references [13] and [14] of the letter (reproduced here as [2] and [3]). They should be replaced by the corrected references given here as [4] and [5] without changing the original numerical order of the references in [1]. The authors apologize for any blight this mistake may have caused.