The master's thesis deals with the design and implementation of a reconfigurable patch antenna. The antenna is fed by a microstrip transmission line. To the microstrip feeder, tuning stubs are connected. Each stub matches the input impedance of the antenna to 50 ? for different operation frequencies. Stubs can be individually connected to the feeder by PIN diodes; operation frequency of the antenna can be switched that way. In the project, the antenna is initially designed for antenna substrate RO3006. Then, the design will be converted to the substrate ARLON AD600 selected for the realization. In the project, modifications of stubs will be proposed to properly connect the PIN diodes. Functionality of the designed antenna will be verified by modeling in Ansoft Designer. The last part will be dealt with implementation of the antenna and the experimental measurement of their properties.

Beam scanning Microstrip (BSMS) antenna is designed to work at center frequency of 10 GHz for using in the scanning applications of 9 GHz to 11 GHz band. The design parameters are defined and by using an Electromagnetic Simulation software program, the parameters are optimized. A Beam Scanning Microstrip Antenna is produced as a prototype and the measurement&rsquo / s results are compared with theoretical results. In conclusion, the values of deviation between theoretical and experimental results are discussed.

The purpose of this research was to design a blood glucose sensing system based on the induced shift in the resonant frequency of an antenna patch operating in the ISM band (5.725 – 5.875 GHz). The underlying concept is the fact that when a person has variations in their blood glucose levels, the permittivity of their blood varies accordingly. This research analyzed the feasibility of using an antenna patch as a blood glucose sensing device in three configurations: 1) as an implantable active sensor, 2) as an implantable passive antenna sensor, and 3) as a non-invasive sensor. In the first arrangement, the antenna is to be implanted inside the body as an active antenna, requiring that its power supply and internal circuitry to be implanted. In the second arrangement, the antenna is also implanted, but would not require a power supply or internal circuity since it would be passive. For the third arrangement, the non-invasive sensing approach, the antenna is placed facing the upper arm while mounted outside the body. In order to evaluate the best approach all the three approaches were simulated using the electromagnetic field tool simulator ANSYS EM15.0 HFSSTM, along with a human tissue model. The tissue model included physiological and electrical characteristics of the human abdomen for simulating the active and passive approaches, and the upper arm for the non-invasive approach. The electromagnetic boundaries were set with perfectly matched layers to eliminate any reflections which would cause a non-physical resonance in the results. Simulation of the active sensing configuration resulted in a resonant frequency shift from 5.76 to 5.78GHz (i.e., a 20 MHz shift) for a simulated blood permittivity variation of 62.0 to 63.6. This corresponds, theoretically, to an approximate glucose shift of 500 mg/dL. The passive configuration simulations did not yield conclusive variations in resonant frequency and this approach was abandoned early on in this research. Thirdly, the non-invasive approach resulted in a simulated shift of resonant frequency from 5.797 to 5.807 (i.e., a 10MHz shift) for simulated blood permittivity variation of 51.397 to 52.642 (an approximate variation of 2000 mg/dL in glucose). In the literature planar, continuous blood-rich layers are used to simulate RF sensing of glucose, which is not applicable when measuring glucose in actual human veins, which are tubular in geometry and of finite extent. Therefore the model employed assumed a 1.8 mm diameter blood vessel, buried under a fatty layer that was capped with skin. The above results, both simulated and verified experimentally, used this more realistic model which is further proof that a practical non-invasive blood glucose measurement system should be possible. The non-invasive approach was tested experimentally by using oil in gel phantoms to mimic the electrical properties of skin, fat, blood and muscle. A fat phantom was placed over a muscle phantom, with a strip of blood phantom within and a skin phantom was placed on top. The blood phantom had a 2000mg/dL variation of D-glucose in the phantom mixture which decreased the relative permittivity from 52.635 to 51.482 and resulted in a shift of resonant frequency from 5.855 to 5.842 (i.e., a 13MHz shift). This is consistent with the non-invasive simulated results thus validating our model of the non-invasive sensing approach. While this variation in blood glucose is non-physical (typical human glucose range can range in the extremes from 30 to 400 mg/dL, where healthy glucose levels vary from 70mg/dL to 180mg/dL) it was necessary to provide a high confidence fit between the simulated and experimental data. This is because the level of precision with which the physical phantoms could be fabricated with was insufficient to match the highly precise simulated data. Analysis on the effect of lateral displacement of the antenna from the blood vessel, its elevation above the skin and variations caused by different skin thickness, and blood vessel depth were evaluated. A calibration technique to correct physical misalignment by the user is proposed in which two additional antennas, located diagonally with respect to the sensing antenna, serve as reference point for placement over the upper arm in line of sight with the blood vessel. Once the non-invasive sensor approach was shown to be viable for continuous glucose monitoring, a sensor platform was designed whereby an RF generator was used to drive the antenna with a frequency sweep between 5.725 to 5.875GHz. A fraction of its output power was coupled to both the antenna and the system analysis circuitry through a directional coupler. The transmitted and received power were then processed with demodulating logarithmic amplifiers which convert the RF signal to a corresponding voltage for downstream processing. Both inputs were then fed into a microcontroller and the measured shift in resonant frequency, fO, converted to glucose concentration which was displayed on glucose meter display.

In this thesis, a wideband dual polarized microstrip antenna is designed, manufactured and measured. Slot coupled patch antenna structure is considered in order to achieve the wideband characteristic. Although rectangular shaped slot coupled patch antennas are widely used in most of the applications, their utilization in dual polarized antenna structures is not feasible due to space limitations regarding the positioning of two separate coupling slots for each polarization. For a rectangular slot, the parameter that affects the amount of coupling is the slot length. On the other hand when a H-shaped slot is considered, both the length of the center arm and the length of the side legs determine the coupling efficiency. This flexibility about the optimization parameters of the H-shaped slot makes it possible to position the two coupling slots within the boundaries of the patch antenna. Therefore, H-shaped slot coupled patch antennas are studied in this thesis. In order to investigate the effects of slot and antenna dimensions on the radiation characteristics of the antenna, a parametric study is performed by analyzing the antenna structure with a planar electromagnetic field simulation software (Ansoft Designer). By the help of the experience gained through this parametric study, a dual polarized patch antenna that can be used at the base station of a cellular system (DCS: 1710&ndash / 1880 MHz) is designed. Before manufacturing the antenna, dimensions of the antenna are re-tuned by considering a finite sized ground plane in the simulations. Finally, the antenna is manufactured and measured. An acceptable agreement is obtained between the measurement and the simulation results.

Radio Frequency (RF) energy transfer is getting increasingly importance in new generations of wireless sensor networks and this trend is tremendously supported by the modern trends to Internet of things (IoT). This promising technology enables proactive energy replenishment for wireless devices. With RF energy, transmission long distances between the energy source and the receiver can be overbridged. The main challenge thereby is the power conversion efficiency from a low level RF input power to a Direct Current (DC) voltage which is able to supply the mobile system. For this purpose, a novel approach for RF DC conversion is proposed. It consists of a modified voltage multiplier RF DC converter circuit by incorporating an inductor at the input of the circuit, which generates an induced voltage able to boost the output circuit and improve the conversion efficiency. Analytical analysis of the novel approach has been carried out to determine the optimal value of the inductor to maximize the output power. The experimental investigations show that the proposed solution is able to improve significantly both the output voltage and the power conversion efficiency, compared to the state of the art, and this especially at low input power ranges, which are often the case. At -10 dBm input power, the modified voltage multiplier RF DC converter circuit can reach 1.71 V output voltage and 49.21 % power conversion efficiency for, respectively, 500 kΩ and 10 kΩ resistive loads. In order to validate the new proposal for the RF transfer system experimentally, microstrip meander line antennas and microstrip patch antenna arrays are designed for different ISM bands, where relevant requirements for RF energy transfer are respected. For each antenna a modified voltage multiplier RF DC converter circuit has been applied and the system is tuned to the corresponding resonant frequency to avoid mismatching. In this investigation several scenarios have been addressed, such as RF transmission energy, RF energy harvesting in Global System for Mobile (GSM) bands and Wireless Local Area Networks (WLAN) band are developed. Field test results show high performances of experimental results in comparison to the state of the art.:1 Introduction 2 Theoretical Background 3 State of the Art of RF Energy Transfer 4 Novel Approach for a RF DC Converter Circuit 5 Antennas Design 6 Experimental Verification at Specific Scenarios 7 Conclusion / Die RF-Energieübertragung (RF) gewinnt in neuen Generationen von drahtlosen Sensornetzen zunehmend an Bedeutung. Dieser Trend wird durch das Internet der Dinge (IoT) weiter unterstützt. Diese vielversprechende Technologie ermöglicht eine proaktive Energieversorgung für drahtlose Geräte. Mit RF-Energie können große Entfernungen zwischen der Energiequelle und dem Empfänger überbrückt werden. Die größte Herausforderung dabei ist der Wirkungsgrad, mit dem von einer niedrigen HF-Eingangsleistung in eine Gleichspannung (DC), mit welcher das mobile System versorgt wird, gewandelt wird. Zu diesem Zweck wird ein neuer Ansatz für einen RF-DC-Wandler vorgeschlagen. Er besteht aus einer modifizierten Spannungsvervielfacher-RF-DC-Wandlerschaltung, die eine Spule am Eingang der Schaltung integriert. Diese erzeugt eine induzierte Spannung, die in der Lage ist die Ausgangsschaltung zu verstärken und den Umwandlungswirkungsgrad zu verbessern. Analytische Untersuchungen zu diesem neuartigen Ansatz wurden durchgeführt, um den optimalen Wert der Spule zu bestimmen und die Ausgangsleistung zu maximieren. Die experimentellen Untersuchungen zeigen, dass die vorgeschlagene Lösung in der Lage ist, sowohl die Ausgangsspannung als auch den Wirkungsgrad der Leistungsumwandlung im Vergleich zum Stand der Technik deutlich zu verbessern. Dies gilt besonders für niedrige Eingangsleistungsbereiche, welche häufig vorkommen. Bei -10 dBm Eingangsleistung kann die modifizierte Spannungsvervielfacher-RF-DC-Wandlerschaltung 1.71 V Ausgangsspannung und 49.21 % Leistungswandlungswirkungsgrad für jeweils 500 kΩ und 10 kΩ ohmsche Last erreichen. Um das neue RF-Übertragungssystem experimentell zu validieren, werden Mikrostreifenmäanderlinienantennen und Mikrostreifen-Patch-Antennenarrays für verschiedene ISM-Bänder ausgelegt, wobei die relevanten Anforderungen an die RF-Energieübertragung eingehalten werden. Für jede Antenne wurde eine modifizierte Spannungsvervielfacher-HF-DC-Wandlerschaltung verwendet und das System auf die entsprechende Resonanzfrequenz abgestimmt, um Fehlanpassungen zu vermeiden. Dabei wurden mehrere Szenarien untersucht, wie z.B. RF-Energieübertragung, RF-Energiegewinnung aus GSM-Bändern und WLAN-Netzwerken. Die Feldtests zeigen eine hohe Leistungsfähigkeit der experimentellen Ergebnisse im Vergleich zum Stand der Technik.:1 Introduction 2 Theoretical Background 3 State of the Art of RF Energy Transfer 4 Novel Approach for a RF DC Converter Circuit 5 Antennas Design 6 Experimental Verification at Specific Scenarios 7 Conclusion