In this paper, a 3D-printed super-wideband (SWB) Spidron fractal cube antenna is proposed. The Spidron fractal configuration is utilized as a self-complementary structure on each face of a 3D frame to attain SWB characteristics. The antenna is excited through a tapered microstrip balun for both mode transforming and impedance matching. A prototype of the proposed antenna, including the 3D frame fabricated with the help of a 3D printer and Spidron fractal patches made of copper tape, is experimentally verified. The measured −10 dB reflection ratio bandwidth is 34:1 (0.44–15.38 GHz). The peak gain varies from 3.42 to 9.29 dBi within the operating frequency bandwidth. The measured radiation patterns are nearly omnidirectional at all operating frequency bands.

In this paper, a low-profile HF (high-frequency) meandered dipole antenna with a ferrite-loaded artificial magnetic conductor (AMC) is proposed. To operate in the HF band while retaining a compact size, ferrite with high permeability is applied to the unit cell of the AMC. The operating frequency bandwidth of the designed unit cell of the AMC is 1.89:1 (19–36 MHz). Thereafter, a meandered dipole antenna is designed by implementing a binary genetic algorithm and is combined with the AMC. The overall size of the designed antenna is 0.06$\times$0.06$\times$0.002 ${\lambda }^3$ at the lowest operating frequency. The proposed dipole antenna with a ferrite-loaded AMC is fabricated and measured. The measured VSWR bandwidth (<3) covers 20–30 MHz on the HF band. To confirm the performance of the antenna, a reference monopole antenna which operates on the HF band was selected, and the measured receiving power is compared with the result of the proposed antenna with the AMC.

In this paper, an extremely low-profile ferrite dipole antenna operating on the VHF band (30–300 MHz) is proposed. The design antenna consists of 44 plate-type ferrite cells arranged into two stacked ferrite layers: a bottom ferrite layer with $2\times 12$ grid cells and a top ferrite layer with $2\times 10$ grid cells. The antenna is excited by an electric loop feeding structure and maximum gain performance is achieved when the loop feeding structure has five loops. To validate the performance of the proposed antenna, an antenna prototype is fabricated and tested at an outdoor range. The antenna weighs 1.45 kg and has electrical dimensions of approximately 0.0636 $\times$ 0.0112 $\times$ 0.0008 ${\lambda }_L^3$ at the lowest operating frequency of 30 MHz. The measured realized gain varies from −31.48 to −2.44 dBi within the VHF band. Reasonable agreement is also obtained between the measurement and simulation results. To assess the performance of the proposed antenna, it was mounted on the integrated mast of an offshore patrol vessel (OPV) model. The antenna on the OPV was also simulated and the results discussed.

A circular sector-shaped dipole antenna with meandered arms based on an artificial magnetic conductor (AMC) is proposed in this study. A compact unit cell of the AMC operating within 19–485 MHz is designed using a ferrite material, which exhibits high-permeability characteristics in the high-frequency (HF), very-high-frequency (VHF), and ultra-high-frequency (UHF) bands. The configuration of the meandered arms is optimally designed using a binary genetic algorithm, so that the antenna combined with the AMC meets the voltage standing wave ratio (VSWR) specification of 3.5:1 or less within the HF, VHF, and UHF bands. The proposed antenna with the AMC is fabricated and measured. The measured VSWR frequency bandwidth (3.5:1 or less) is 25.8:1 (14–361 MHz), and the measured result matches with the simulated result well. Furthermore, to verify the performance of the proposed antenna with the AMC, the measured received power results are compared with a commercial reference antenna operating in HF, VHF, and UHF bands.

In this letter, an electrically small Spidron fractal loop antenna operating in the VHF band is proposed. The ferrite material, which consists of a nickel-zinc combination, is loaded into inside of the loop antenna to increase the gain of the antenna in the low frequency band. To minimize the magnetic loss of the ferrite in the high frequency band, the amount and configuration of the ferrite are optimized using a genetic algorithm. Through this optimization step, the amount of the ferrite is decreased to 37.5% and the gain of the antenna in the high frequency band is improved. The size of the proposed antenna is 0.0242 $\times$ 0.0242 $\times$ 0.0051 ${\lambda }_L^3$ at the lowest operating frequency. The proposed antenna was fabricated to verify the performance, and the simulated and measured results are in good agreement. The measured peak gains varied from −31.6 to −1.9 dBi within the measured frequency band. To examine the performance of the proposed antenna mounted on an unmanned aerial vehicle model (UAV), the antenna on a UAV was also simulated and the results were discussed. The simulated realized peak gains of the antenna on the UAV and on flat ground are similar.

한국전자파학회논문지 (The Journal of Korean Institute of Electromagnetic Engineering and Science)