# A Low-Profile HF Meandered Dipole Antenna with a Ferrite-Loaded Artificial Magnetic Conductor
## 3 Experimental Verification  
### Performance of the Designed Antenna with the AMC  
A prototype of the designed antenna with the AMC is fabricated and measured to verify the performance. Figure 6 presents a photograph of the fabricated meandered dipole antenna with the AMC. The antenna and AMC were etched separately and then electrically  
Figure 4: Design concept of a meandered dipole antenna.  
Figure 5: Geometry of the proposed antenna with the AMC: (**a**) meandered dipole antenna; (**b**) \(8\times 8\) AMC; (**c**) side-view.  
and physically connected to each other using copper tape and instant glue, respectively. Styrofoam is utilized to create an air gap between the substrate of the meandered dipole antenna and the AMC. The overall size of the fabricated antenna is \(1000\times 1000\times 30.22\) mm\({}^{3}\).  
Figure 7 presents the simulated and measured VSWRs of the proposed antenna with the AMC. An Agilent 8510C network analyzer was utilized to measure the VSWR. The proposed antenna meets VSWR characteristics (<3) on the HF band of 20-30 MHz. The discrepancy can be attributed to inaccuracies during the fabrication process, experimental tolerances, and to the assembly process.  
To verify the effects of the AMC, the VSWR characteristics of the antenna with and without the AMC were simulated. The comparison of the VSWRs of the antenna according to the presence of the AMC is shown in Figure 8. When the AMC is applied, the antenna  
Figure 6: Photograph of the fabricated antenna with the AMC: (**a**) top-view; (**b**) side-view.  
Figure 7: Simulated and measured VSWRs of the proposed antenna with the AMC.  
meets the VSWR characteristics (\(<\)3) in the 20-30 MHz band. On the other hand, the antenna does not satisfy the VSWR characteristics in the 20-30 MHz band. Therefore, it can be confirmed that impedance matching of the antenna is improved by applying the AMC.  
Simulated radiation patterns of the proposed antenna with the AMC at 20 MHz, 25 MHz, and 30 MHz are illustrated in Figure 9. Due to the AMC effects, the main beam direction is formed on the \(+z\)-axis. Furthermore, it can be seen that the distance between the antenna and the AMC is closer than \(\lambda_{L}/4\) (\(\lambda_{L}\) is the wavelength of the lowest operating frequency in free space), which is the required distance between the antenna and a general reflector at which the performance of the antenna does not deteriorate. Despite the AMC works as reflector, the size of the AMC is significantly small related to the wavelength of the operating frequency of the antenna. Therefore, the back radiation is inevitably occurred.  
Figure 8: Simulated VSWRs of the proposed antenna with and without of the AMC.  
Figure 9: Simulated radiation patterns of the meandered dipole antenna with the AMC : (**a**) 20 MHz; (**b**) 25 MHz; (**c**) 30 MHz.  
The realized gain of the proposed antenna with the AMC at the \(+z\)-axis is shown in Figure 10. The realized gain varies from \(-22.2\) dBi to \(-16\) dBi within the operating frequency bandwidth. Consequently, it can be confirmed that the gain characteristics of the proposed antenna with the AMC are higher within the 20-30 MHz band compared to those of the reference commercial antenna [28], for which the corresponding values are approximately \(-24\) dBi and \(-17.5\) dBi at 20 MHz and 30 MHz. As a result, the proposed antenna with the AMC is shown to have reasonable gain characteristics.