## 3 Experimental Verification
### Experimental Results of the Designed Antenna with the AMC on a Manpack  
Figure 9a shows a hexahedral ground plane for a manpack structure of the type worn by a person. The dimensions of the hexahedral ground plane are \(W\ \times\ L\ \times\ H\) (\(W\) = 500 mm, \(L\) = 400 mm and \(H\) = 200 mm) taking into account the size of the manpack application [24]. The Spidron fractal dipole antenna with the AMC on the hexahedral ground plane is shown in Figure 9b. The proposed antenna with the AMC and the hexahedral ground plane were bonded with double-sided tape. Simulated VSWRs with and without the hexagonal ground plane of the Spidron fractal dipole antenna with the AMC were compared. As shown in Figure 9c, the simulation results confirmed that the performance was not degraded regardless of whether or not the hexahedral ground plane was applied.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Description** & **Operating Bandwidth** & **Size (\(\lambda_{L}^{3}\))** \\ \hline
[2] & 10:1 & 0.024 \(\times\) 0.024 \(\times\) 0.005 \\
[3] & 1.68:1 & 0.72 \(\times\) 0.72 \(\times\) 0.07 \\
[7] & 3.33:1 & 0.11 \(\times\) 0.11 \(\times\) 0.003 \\ Proposed antenna & 25:1 & 0.033 \(\times\) 0.026 \(\times\) 0.001 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison between the proposed antenna and designed antennas in previous studies (note that \(\lambda_{L}\) is the wavelength corresponding to the lowest operating frequency).  
Figure 8: Simulated realized gain on the \(+z\)-axis of the Spidron fractal dipole antenna with the AMC.  
Figure 10a illustrates the received power measurement setup when a manpack is worn by a person. To compare the received power of the Spidron fractal dipole antenna with the AMC, a reference antenna (OMNI-A0245, ALARISANTENNAS [25]) was selected, and the power levels received on the commercial FM band (88-108 MHz) and the DMB (digital multimedia broadcasting) band (174-216 MHz) in South Korea were compared. Figure 10b depicts the measured received power levels of the Spidron fractal dipole antenna with the AMC and the reference antenna. The difference in the average reception power between the Spidron fractal dipole antenna with the AMC and the reference antenna was 8.5 dB on the FM band and 3.2 dB on the DMB band. On the FM band, where the difference in the gain characteristics between the Spidron fractal dipole antenna with the AMC and the reference antenna was large, the difference in the reception power was large, while on the DMB band, where the difference in the gain was relatively small, the difference in the reception power gain was also small. Moreover, the differences in the received power were caused by the different sizes and the different mounting positions. The power received by the antenna was analyzed by a signal analyzer  
Figure 9: (**a**) Geometry of the hexahedral ground plane; (**b**) photograph of the Spidron antenna with the AMC bonded onto the hexahedral ground plane; (**c**) simulated VSWRs of the Spidron fractal dipole antenna with the AMC with and without the hexahedral ground plane.  
(FSV signal and spectrum analyzer, Rohde & Schwarz) and the received power values in Figure 10b are shown with a 45 dB offset.