The experimental study of mutual coupling in conformal array

Abstract

Also, the top and bottom CPW layers are assumed to be similar due to the fact that the design in this letter aims at having an equal power from the three output ports.The design equations (1)- (10) can now be used to find the initial design dimensions (w m , w c , and w s ) of the three-way equal-power divider. Concerning the length of the coupled structure (l), it is equal to quarter of the effective wavelength at the center of the passband (6.85 GHz). RESULTSAn equal-power three-way power divider aimed at the operation in the UWB range 3.1-10.6 GHz was designed, developed, and tested. Rogers RO4003C (dielectric constant ¼ 3.55, thickness ¼ 0.508 mm, and loss tangent ¼ 0.0027) was used as the substrate. Using the proposed design approach and with the help of the optimization capability of the software CST Microwave Studio, parameters of the device (shown in Fig. 1) were found to be: w s ¼ 6.7 mm, w c ¼ 1.7 mm, w m ¼ 2.1 mm, width of the 50 X microstrip input/output ports ¼ 0.75 mm, width of the central conductor in the 50 X CPW output ports ¼ 0.6 mm, and width of the slot in the CPW output ports ¼ 0.2 mm. The length of the coupled layers l is equal to quarter of the effective wavelength at the center frequency of operation (6.85 GHz). After optimization, l was found to be 4.6 mm. A photograph of the developed device is depicted in Figure 4. It has a compact size with an overall dimension of 25 Â 25 mm 2 . The designed power divider was tested via simulations and measurements. The output power at the three output ports, as shown in Figure 5 (because of symmetry S31 ¼ S41), is equal to À4.77 6 1 dB (ideal value ¼ À4.77 dB) across the band from 3.1 to 11.5 GHz revealing an UWB performance. The isolation between the three output ports is presented in Figure 5 (because of symmetry S32 ¼ S42). The simulated and measured isolation between ports 3 and 2 (or between the ports 4 and 2) is better than 20 dB, whereas it is better than 18 dB across the band from 3 to 6.5 GHz and better than 13 dB across the whole UWB (3.1-0.6 GHz) between the ports 3 and 4. The return loss at the input/output ports of the device is revealed in Figure 6 (note that because of symmetry S44 ¼ S33). It is better than 16 dB at the four ports of the device across the band from 3 to 10.6 GHz. In general, there is a good agreement between the simulated and measured results shown in Figures 5 and 6. CONCLUSIONSA compact three-way power divider with UWB performance has been presented. The proposed divider utilizes a simple broadside-coupled microstrip/CPW structure. The simulated and measured results of the developed device have shown equal three-way power division, good return loss, and isolation across the band from 3.1 to 10.6 GHz. that the element patterns in array are modeled simply as a cosine function [6, 7]. A few methods use the element pattern represented by the calculated or measured results for the isolated elements [8]; nevertheless, it may not be applicable for a practical conformal array, where each element ''faces'' a different environ...

Mutual coupling compensation of the conformal array antenna based on the active element pattern method

“…When calculating the mutual coupling coefficient between the elements in the rules array, it usually can be used Fourier coefficient method according to its periodic. But this kind of method is not suitable for conformal array [6].…”