ABSTRACT
Low profile compact active and tunable antennas are needed in several communication systems. Printed antennas possess attractive features such as low profile, flexibility, light weight, small volume, and low production cost. The resonant frequency of microstrip antennas is altered due to environmental conditions, different antenna locations, and different modes of operation. The communication and biomedical industry has undergone continuous growth in the last decade. Low profile compact tunable antennas are crucial in the development of wearable human biomedical systems. Varactor diodes are semiconductor devices that are used in many microwave systems where a voltage-controlled variable capacitance is required. A varactor provides electrically controllable capacitance, which can be used in tuned circuits. A compact tunable microstrip dipole antenna has been designed to provide horizontal polarization. Tuning varactors are voltage-variable capacitors designed to provide electronic tuning of microwave components. Active wearable antennas may be used in receiving or transmitting channels.
