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The detailed analysis, design and optimization of a reconfigurable antenna based on a periodically stub-loaded half-mode substrate-integrated waveguide (HMSIW) cavity is presented in this paper. The analysis demonstrates an excellent prediction of the resonance frequency for the cavity with an error of less than 2% compared to numerical simulations performed over a wide range of parameters. The fast computation of the resonance frequency based on the analytical model gives deep insight into the antenna operation and allows an efficient optimization process. The reconfigurable antenna has been designed and optimized to cover the whole S-band (WR-284 waveguide band), i.e. 2.60 GHz to 3.95 GHz, using 3 varactors with measured capacitance varying from 0.149 pF to 1.304 pF. Experimental results validate the concept across the whole tuning range, with a return loss and antenna gain greater than 15 dB and 2.1 dB, respectively at resonance.

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This paper focuses on wireless transcutaneous RF communication in biomedical applications. It discusses current technology, restrictions and applications and also illustrates possible future developments. It focuses on the application in biotelemetry where the system consists of a transmitter and a receiver with a transmission link in between. The transmitted information can either be a biopotential or a nonelectric value like arterial pressure, respiration, body temperature or pH value. In this paper the use of radio-frequency (RF) communication and identification for those applications is described. Basically, radio-frequency identification or RFID is a technology that is analogous to the working principle of magnetic barcode systems. Unlike magnetic barcodes, passive RFID can be used in extreme climatic conditions-also the tags do not need to be within close proximity of the reader. Our proposed solution is to exploit an exciting new development in making circuits on polymers without the need for battery power. This solution exploits the principle of a surface acoustic wave (SAW) device on a polymer substrate. The SAW device is a set of interdigitated conducting fingers on the polymer substrate. If an appropriate RF signal is sent to the device, the fingers act as microantennas that pick up the signal, and this energy is then converted into acoustic waves that travel across the surface of the polymer substrate. Being a flexible polymer, the acoustic waves cause stresses that can either contract or stretch the material. In our case we mainly focus on an RF controllable microvalve that could ultimately be used for fertility control.