The frequency agility of an electrically small, ultralow-profile, VHF-UHF antenna, which has evolved from a complementary split ring resonator unit cell design, is studied numerically. Simulation results demonstrate that when a varactor is integrated into the original 300-MHz passive antenna and its capacitance is varied linearly from 0 to 5.8 pF, a tuning ratio of 2.02:1 and an effective fractional bandwidth of 67.6% (approximately 679.74 times the original value) is achieved while maintaining |S11| < -10dB (VSWR < 2), and a stable dipolar directivity pattern over the entire bandwidth. The overall dimensions of the proposed antenna at the maximum frequency f max = c/λmin are 0.03(λmin) 2 × 0.0066λmin.
- frequency agile
ASJC Scopus subject areas
- Condensed Matter Physics
- Atomic and Molecular Physics, and Optics
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering