Investigation on tuning capabilities of self-diplexing antenna using different liquid dielectrics

This article investigates the possibilities of frequency tuning of a Self-diplexing antenna (SDA) using different liquid dielectrics. Tuning analysis is carried out using the fluidic pockets introduced into the substrate by drilling blind vias starting at the bottom layer. To examine the frequency tuning, the pockets can be filled with either air, olive oil, transformer oil, acetone, or distilled water and sealed with copper tape. The experimental results demonstrate that the proposed antenna can be configured to operate in the 3.25 to 3.52 GHz and 4.5 to 5.04 GHz bands. The proposed SDA is designed and fabricated on a substrate of 1.575 mm thick Rogers 5880 ( $ \epsilon _r $ ϵr = 2.2 and tan δ = 0.0009). It is observed that frequency shift is more when using higher permittivity fluids. The proposed antenna model has competitive features such as simple design, compact size ( $ 0.34 \lambda _g^2 $ 0.34λg2), better isolation (>30 dB), and fine-tuning, which makes it suitable for modern multiband and multifunctional gadgets. The simulated and measured circuit responses are in good agreement.