Changes

In the last section of the articleNext, we will examine two a strip-fed cylindrical dielectric resonator antenna designs, one featuring linear polarization similar to all the previous examples and the other featuring circular polarization. design as shown in Figure 45 shows the geometry of a linearly polarized, strip-fed cylindrical DRA. The dielectric block has a radius of a = 10.3mm and a height of h = 34.3mm with a relative permittivity of ε_r = 9.4. A vertical metal strip of length L = 12mm and width w = 1mm is used to excite the cylindrical dielectric resonator in a similar manner to the rectangular DRA of Figure 2. Similarly, one can use either the DWM or TRM methods to derive the characteristic equation of the HEM_mnl modes of the cylindrical dielectric resonator. These equations involve a combination of the Bessel functions of the first kind J_n(x) and the modified Bessel functions of the second kind K_n(x). According to the analysis presented by Ref. [3], this particular cylindrical DRA shown in Figure 45 supports the HEM₁₁₁ and HEM₁₁₃ modes with resonant frequncies frequencies 2.90GHz and 3.72GHz, respectively. This problem was simulated using [[EM.Cube]]'s FDTD solver, and the computed reutrn loss of the DRA is plotted in Figure 46. This figure also shows the simulated and measured results presented by Ref. [3]. The simulated results were obtained using ANSYS HFSS based on the finite element method (FEM). Similar to the previous case, the dimensions of the metallic ground plane were not given in Ref. [3]. Both [[EM.Tempo]] and Ref. [3] show a 10-dB bandwidth of 800MHz, but [[EM.Tempo]]'s bandwidth is shifted up by 200MHz starting at 4.25GHz and ending at 4.05GHz. Figures 47 and 48 show the 3D far field radiation patterns of the cylindrical DRA at the two resonant frequencies f = 3.29GHz and f = 3.83GHz. From these two figures, the directivity of the DRA is seen to be 6.79dBi and 9.403dBi at f = 3.29GHz and f = 3.83GHz, respectively. Ref. [3] reports measured antenna gain values of 7dBi at 3.29GHz and 10dBi at 3.83GHz.

<table><tr><td>[[Image:ART DRA62.png|thumb|left|480px|Figure 4845: 3D far field radiation pattern of the cylindrical dielectric resonator antenna of Figure 45 computed at f = 3.83GHz by [[EM.Tempo]].  Figure 47: 3D far field radiation pattern of the cylindrical dielectric resonator antenna of Figure 45 computed at f = 3.29GHz by [[EM.Tempo]].</td></tr>Figure 46: Return loss of the cylindrical dielectric resonator antenna of Figure 45, solid red line: [[EM.Tempo]] (FDTD) results, red symbols: simulated data presented by Ref. [3], and blue symbols: measured data given by Ref. [3].</table>