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This paper describes the design, fabrication, packaging, and performance characterization of a conformal helix antenna created on the outside of a capsule endoscope designed to operate at a carrier frequency of 433 MHz within human tissue. Wireless data transfer was established between the integrated capsule system and an external receiver. The telemetry system was tested within a tissue phantom and in vivo porcine models. Two different types of transmission modes were tested. The first mode, replicating normal operating conditions, used data packets at a steady power level of 0 dBm, while the capsule was being withdrawn at a steady rate from the small intestine. The second mode, replicating the worst-case clinical scenario of capsule retention within the small bowel, sent data with stepwise increasing power levels of -10, 0, 6, and 10 dBm, with the capsule fixed in position. The temperature of the tissue surrounding the external antenna was monitored at all times using thermistors embedded within the capsule shell to observe potential safety issues. The recorded data showed, for both modes of operation, a low error transmission of 10 packet error rate and 10 bit error rate and no temperature increase of the tissue according to IEEE standards.

Abstract-This paper describes a steerable broadband dielectric antenna with 30% fractional bandwidth, operating at 11 GHz. The structure consists of a hollow cylindrical dielectric pellet of permittivity 6 fed by four probes. Two methods are described for beam forming: 1-Beam forming has been achieved by individually switching between excited probes. The switched excitation mechanism provides the antenna with a reconfigurable radiation beam that can be moved in the azimuth plane. 2-Variable phase excitation of several probes. Complete azimuth sweep was demonstrated by both methods, allowing any desired angle of beam directions. Simulation and experimental results are presented to illustrate the advantages of both designs.

Results from measurements of the direct and converse magnetoelectric effect on a three-layer, epoxy-bonded, laminate composite are presented. The laminae are a single transversely-polarised piezoelectric elements (PZ29) sandwiched between two longitudinal-magnetically polarised magnetostrictive TD elements (Terfenol-D-TX GMM). The direct ME effect was determined by measuring laminate output with a Helmholtz-generated AC field (of up to 7Oe) in the range 50 Hz-100 kHz biased by a DC field (0-1000Oe). Peak voltage output occurred at the sample's mechanical resonant frequency, its value otherwise depending on the strength and direction of the applied magnetic field. The peak output is 3061mV at 3 Oe AC field and 1000 Oe bias, equivalent to 74.4 V/cm Oe was achieved. The peak output coefficient, however was 93.6V/cm Oe at 0.1Oe AC field and 1000Oe DC bias. The reduction at higher drive amplitudes was attributed an increased Young's modulus of TD phase. Anomalous peaks in the sample's output, related to the proximity of the DC electromagnet poles, are also investigated and explained. The converse magnetoelectric effect was measured by recording the voltage induced in a solenoid encompassing the ME and exposed to a DC bias field and the PZ phase driven by a 10 V AC source. A peak output is shown to depend on the strength of the applied DC magnetic field and gave a maximum output voltage of 600 mV, representing 15.4 Oe at the sample's mechanical resonant frequency. This equates to a converse magnetoelectric coefficient of 55 Oe cm/ kV.

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