An SISL Differentially Fed Frequency Reconfigurable Antenna Without Passive Components for the Bias Circuit

This communication presents a substrate-integrated suspension line (SISL)-based frequency reconfigurable microstrip patch (MP) antenna design without any passive components such as capacitors, inductors, and resistors and is easy to interface with the differential circuitry of radio frequency (RF) systems. The design suffers from loading an inductor or a resistor to isolate the RF signal onto the direct current (dc) bias line because the dc bias line is placed on the virtual alternating current (ac) ground plane. The coupled fed allows for the avoidance of the need for capacitors to isolate the dc signal, creating a favorable isolation environment for the antenna dc and ac circuits. As a result, the proposed antenna can achieve the desired frequency configuration without using passive components like capacitors, inductors, and resistors. The antenna can cover the 1.61–2.71 GHz band, according to measurements. In the whole tuning range, stable radiation pattern properties are attained.