In this article, a 2 × 2 circular polarized (CP) antenna array, which is using sequential rotation (SR) technique in feeding network, has been introduced. The feeding network uses two 90° arcs and several rectangular lines with the same width. The length of these elements is multiple of λg/4 to produce 90° phase difference in 4 outputs of feeding network. By connecting the patch elements to the feeding network, which have been surrounded with radiating patch elements, design of 2 × 2 patch array has been completed. This array antenna with an incomplete ground which helps to have a better impedance matching, has been caused to reach a wider axial ratio (AR) and impedance bandwidth. The prototype of the proposed antenna array is built to validate the antenna performance. By using these techniques, a common bandwidth of 1.15 GHz has been achieved for impedance bandwidth (S11 < 10 dB) and AR bandwidth (AR < 3 dB) and 7.5 dBi maximum gain. In addition, the gain is more than 4 dBi in desired frequency range. According to the frequency range of 2.8‐3.95 GHz, the proposed antenna is suitable for S‐band applications.

A 2×2 circularly polarised (CP) antenna array with four square radiating patch elements has been introduced here. The array elements are sequentially rotated and have been fed by a simple single‐layer feeding network with sequential phase structure. This feeding network generates successive phase difference at its four outputs. To have a wide CP bandwidth, the proposed method of feeding network has been combined with new simple tuning stubs which are embedded in radiating patch elements. The common reflection coefficient bandwidth (S11<−10thinmathspacedB) and axial ratio (AR) bandwidth (AR <3 dB) is 1000 MHz which covers 1.5–2.5 GHz frequency band and according to the centre frequency of 1.8 GHz, the frequency bandwidth is ∼55.5%. Furthermore, the peak gain of the proposed antenna array is ∼7.5 dBi at the frequency range of 1.7–2.3 GHz.

Abstract-A novel feeding network is investigated both theoretically and experimentally. The proposed system with combination of a Wilkinson power divider and two branch-Line couplers is established. The output signals of the system have the same amplitude and 90 • phase difference with each other. The size reduction technique is applied to minimize the physical size of the proposed network. In this technique, the ground of the structure is defected, and distributed capacitors and inductors are added to empty space of the branch-line couplers. Moreover, meandered lines are used in order to match the output impedance of the Wilkinson power divider arms and reduce its size. The initial design realized in 2.5 GHz shows the fractional bandwidth of 24%. Then a miniaturized structure is fabricated with 42% smaller size than the main structure while it shows similar electrical performance. For both cases, measurement and simulation results are in good agreement with each other.

This work addresses a double stacked array antenna with linear and circularly conformal disposition of patch elements. The single patch element is designed in the GHz band based on the inkjet-printing technique. The idea is to generate a microstrip lines using conductive silver ink which is applied on a thin Kapton film. To improve the mechanical stability, a high impact polyester (HIPS) is used as a substrate to fix the Kapton layers which also improves the impedance matching bandwidth. After designing the single patch element with . % impedance bandwidth under − and . directivity, the linear array antenna is designed to improve impedance bandwidth to . % and directivity to . . Due to the possibility of using printing technique, to make HIPS substrate and the flexibility of Kapton layers, the idea of placing eight single patch elements on a printed cylindrical structure is created to achieve the omnidirectional pattern. Therefore, the combination of inkjet-printing and printing techniques will pave the way for manufacturing compact, low cost and light weight antennas for many applications such as wireless local area network or unmanned aerial vehicles.

No abstract