Why the Magnetic Loss Tangent Is Not a Relevant Constraint for Permeable Conformal Antennas

A Low-Profile, Electrically Small Ferrite Core-Loaded Grounded Split Ring Resonator Antenna for Military VHF/UHF Communication

“…The ferrite tiles of the antenna weighed 14.3 kg, and the antenna satisfied the electrical size ka of 0.34 with an extremely thin height of 0.005λ. The proposed low-profile but electrically small antenna showed superior radiation performance compared with previously published antennas with ferrite cores [10], [23], and [26][27]. This study presented the design, analysis, and experimental demonstration of a grounded SRR metamaterial-inspired wideband VHF/UHF communication antenna loaded with a relatively lighter weight ferrite core.…”

“…The minimum realized gain satisfies -14.5 dBi at 30.4 MHz, which is the highest among the references in the comparison table and shows an upward trend with increasing frequency. Although the electrical size is slightly larger than [23], this work represents an improved minimum realized gain in the matched band. In terms of weight, the proposed antenna is heavier compared to [26][27]; however, it is worth mentioning that the weight increases by about 6.3 times when the lowest matched frequency is lowered from 90 MHz [27] to 60 MHz [26], but only by 2.5 times when it is down to 30.4 MHz of this work.…”

“…Conventional studies on these ferrite applications primarily utilized low-loss ferrite to improve the radiation efficiency of a loop antenna [21][22]. However, the magnetic loss must not be a relevant constraint in designing an efficient loop from the calculation of the radiation efficiency of an antenna by considering the complex permeability of ferrite with no approximation [23]. Thus, in contrast to the conventional concepts, a highly efficient loop antenna can be designed using a high-loss ferrite core.…”

Ferromagnetic Resonance-Enhanced Electrically Small Antennas

“…Comparing (3.10) with (2.11), two similar expressions sharing the term ′′ ( ′ ) 2 + ( ′′ ) 2 ⁄ in the denominator of suggests that high radiation efficiency will be achieved under the same three circumstances regarding the complex permeability of the thin-film ferrite, mentioned in [29] and [30] [30] and this dissertation, which is trivial for determining the impact of ′′ on the radiation efficiency of ESAs.…”

“…In early studies of ferrite rod antennas, the permeability of ferrite cores was considered to be constant. Engineers in [29] did include two classic frequency-dependent susceptibility models in analysis when specify the material selection rules for penetrable antenna cores, but their antenna prototype was not designed to operate in the bandwidth where resonance shown in the two classic models for susceptibility was involved. So the role that resonance plays in affecting ESA's performance was not examined.…”