"Transmission loss needs to be considered in the design of telecommunication systems. If telecommunication systems have high transmission loss, the signals lose too much of their strength, which results in poor reception in television networks and lost calls in cellular networks. Total transmission loss, in the MHz-GHz range, has several different loss components, some of which are poorly characterized. Conductor loss is the largest loss component and the most difficult to predict. It is known that the conductor geometry or features influences the conductor loss. However, current numerical, analytical and empirical tools do not accurately predict this loss component, and there is little experimental data available to explain and show the impact of these conductor geometries. The conductor shape is heavily influenced by the ceramic substrate surface roughness, and this is especially true for printed circuit boards fabricated with thick-film technology. The two conductor features of interest are the conductor-edge angle and conductor-ceramic interface. For thick-film circuits, the edge of the conductor does not have a square cross section but has a tapered shape or angle. The conductor-ceramic interface is also rough at the micron scale. Since the current density is concentrated at the extremities of the conductor then these features, conductor-ceramic interface and conductor edges, can potentially have a large impact on conductor loss. For this study, the surfaces of ceramic substrates were subjected to different surface finishes that resulted in distinctly different surface characteristics. This in turn resulted in a range of conductor-ceramic interfaces and conductor-edge angle geometries. The impact of the conductor-edge angle and conductor-ceramic interface features on conductor loss was measured over a range of frequencies and conductor conductivities to ascertain the level of their contribution. It was shown quantitatively that the conductor-edge angle was significantly altered by the surface roughness and heavily influenced the conductor loss result. The consensus for decades has been that greater surface roughness causes the ceramic-conductor interface geometry to have a greater impact on conductor loss, increasing the conductor loss. However, this study has shown that greater surface roughness also causes the conductor-edge angle feature to have a smaller or reduced impact on conductor loss, improving the conductor loss result - this has not been considered previously. Focusing on only one of these features can give an anomalous loss prediction; both features need to be considered for the calculation of conductor loss for thick-film applications. The low frequency loss results are as expected but the high frequency (greater than 5GHz) results depend on edge angle and therefore thick-film paste viscosity, and substrate surface roughness. "

<p>This is a part of the project “Radio telescope system” working at 1.42 GHz, which includes designing of patch antenna and LNA. The main objective of this thesis is to design a two stage low noise amplifier for a radio telescope system, working at the frequency 1.42 GHz. Finally our aim is to design a two stage LNA, match, connect and test together with patch antenna to reduce</p><p>the system complexity and signal loss.</p><p>The requirements to design a two stage low noise amplifier (LNA) were well studied, topics including RF basic theory, layout and fabrication of RF circuits. A number of tools are available to design and simulate low noise amplifiers but our simulation work was done using advanced design system (ADS 2004 A). The design process includes selection of a proper device, stability check of the device, biasing, designing of matching networks and layout of total design and fabrication. A lot of time has been</p><p>spent on designing of impedance matching network, fabrication and testing of the design circuits and finally a two stage low noise amplifier (LNA) was designed. After the fabrication work, the circuits were tested by the spectrum analyzer in between 9 KHz to 25 GHz frequency range. Finally the resulting noise figure 0.299 dB and gain 24.25 dB are obtained from the simulation.</p><p>While measuring the values from the fabricated circuit board, we found that bias point is not stable due to self oscillations in the amplifier stages at lower frequencies like 149 MHz for first stage and 355 MHz for second stage.</p>

This is a part of the project “Radio telescope system” working at 1.42 GHz, which includes designing of patch antenna and LNA. The main objective of this thesis is to design a two stage low noise amplifier for a radio telescope system, working at the frequency 1.42 GHz. Finally our aim is to design a two stage LNA, match, connect and test together with patch antenna to reduce the system complexity and signal loss. The requirements to design a two stage low noise amplifier (LNA) were well studied, topics including RF basic theory, layout and fabrication of RF circuits. A number of tools are available to design and simulate low noise amplifiers but our simulation work was done using advanced design system (ADS 2004 A). The design process includes selection of a proper device, stability check of the device, biasing, designing of matching networks and layout of total design and fabrication. A lot of time has been spent on designing of impedance matching network, fabrication and testing of the design circuits and finally a two stage low noise amplifier (LNA) was designed. After the fabrication work, the circuits were tested by the spectrum analyzer in between 9 KHz to 25 GHz frequency range. Finally the resulting noise figure 0.299 dB and gain 24.25 dB are obtained from the simulation. While measuring the values from the fabricated circuit board, we found that bias point is not stable due to self oscillations in the amplifier stages at lower frequencies like 149 MHz for first stage and 355 MHz for second stage.

No description available.

Master of Science / Department of Electrical and Computer Engineering / William Kuhn / From 2004 to 2008, Kansas State University's Electrical and Computer Engineering (ECE) department, along with the NASA Jet Propulsion Laboratory and Peregrine Semiconductor, researched design techniques for producing a low-power, 400 MHz micro-transceiver suitable for future use on Mars scout missions. In 2012, Dr. Kuhn's Digital Radio Hardware Design class, ECE765, adapted the K-State circuit designs from this research project to investigate the possibility of producing a 2.4 GHz micro-transceiver in Peregrine Semiconductor’s newer 0.25 [mu]m Silicon on Sapphire process. This report expands upon the work completed in the Digital Radio Hardware Design (ECE765) course. The schematics and layout of the subsections of the receiver portion of the micro-transceiver chip, consisting of a transmit/receive switch, low-noise amplifier, mixer, intermediate-frequency amplifiers, and an analog-to-digital converter are described. Circuits designed to date require a total of 15 mW to operate. This report is intended as a guide for future students who will take over this project, make modifications, adapt the transmit portion of the micro-transceiver from previous work, and finish layout before fabrication of a full 2.4 GHz prototype chip.

Because of the tough competition inthe telecom business there is aconstant push for higher capacity anddata rates and the companies producingthe telecommunications equipment needmore cost effective products to stayahead of competitors. It is thereforeinteresting to evaluate thepossibilities to use unlicensedfrequency bands at higher frequenciesas a complement to the traditionallower frequency bands. This study isfocusing on the 5.8 GHz band, which ismainly used for WLAN applications. Akey component in most transmitter (TX)designs is is the quadraturemodulator, which upconverts theinformation signal to desired carrierfrequency. In this study an attempt toevaluate the commercially availablequadrature modulator ADL5375 at 5.8GHz. An AWR Visual System Simulator(VSS) model based on measurements ofkey parameters of ADL5375 isconstructed. An attempt is made to seewhether a TX design can pass thespecifications set by 3rd GenerationPartnership Project (3GPP) for theLong Term Evolution (LTE) standard. Totest this an LTE signal source wasalso constructed. No certainconclusions can be drawn withoutputting the modulator in a complete(TX) design but the results indicatethat it might be possible to use it ina (TX) design for the 5.8 GHz band.

As lower microwave frequency bands become saturated with users, there is a motivation for the research of applications that utilize higher frequencies, especially the 60 GHz band. This band is plagued with high atmospheric absorption due to atmospheric oxygen, but has a lot of bandwidth, which makes it desirable for multi-media applications. Recently, research of wideband digital links within the 60 GHz band gained the interest of the wireless communication industry when the FCC announced that a license is not required for a wideband digital signal in this band. Previous research on 60 GHz signals focused on how much attenuation due to atmospheric oxygen exists in the link. But a look at the physical properties of atmospheric oxygen reveals both the reason why atmospheric oxygen absorbs electromagnetic waves and how pressure affects atmospheric oxygen. Atmospheric oxygen resonates at 60 GHz due to transitions between its three closely spaced rotational states. These transitions, combined with the magnetic dipole moment of atmospheric oxygen, cause attenuation and phase dispersion in electromagnetic waves. At lower pressures, the individual resonance lines of atmospheric oxygen appear in the attenuation and the phase dispersion plots. As pressure increases, the resonance lines broaden and contribute to neighboring resonant lines. The effect of attenuation and phase dispersion in a wideband signal becomes greater at lower atmospheric pressures, which results in signal distortion. The signal distortion leads to more bit errors and results in the presence of inter-symbol interference (ISI) in the received signal. This thesis aims to analyze the effects of atmospheric oxygen on a wideband digital link, especially at lower pressures and higher data rates. In order to simulate the effects of atmospheric oxygen in the atmosphere, an empirical atmospheric model was used, which characterizes the behavior of oxygen under various atmospheric pressures. A wideband communication system was simulated with the absorption and dispersion due to atmospheric oxygen represented as a transfer function and placed in the link part of the system. Eye diagrams were used to view the impact of the atmospheric oxygen attenuation and phase dispersion in the signal. Also bit error rate plots were computed in order to determine the extra margin needed. / Master of Science

Sharing a band of frequencies in the radio spectrum among multiple wireless systems has emerged as a viable solution for alleviating the severe capacity crunch in next-generation wireless mobile networks such as 5th generation mobile networks (5G). Spectrum sharing can be achieved by enabling multiple wireless systems to coexist in a single spectrum band. In this dissertation, we discuss the following coexistence problems in spectrum bands that have recently been raising notable research interest: 5G and Fixed Satellite Service (FSS) at 27.5-28.35 GHz (28 GHz); 5G and Fixed Service (FS) at 71-76 GHz (70 GHz); vehicular communications and Wi-Fi at 5.85-5.925 GHz (5.9 GHz); and mobile broadband communications and radar at 3.55-3.7 GHz (3.5 GHz). The results presented in each of the aforementioned parts show comprehensively that the coexistence methods help achieve spectrum sharing in each of the bands, and therefore contribute to achieve appreciable increase of bandwidth efficiency. The proposed techniques can contribute to making spectrum sharing a viable solution for the ever evolving capacity demands in the wireless communications landscape. / Ph. D.

This thesis presents the results of a 28 GHz continuous-wave (CW) diffraction measurement campaign in the Washington, DC area. It describes the measurement approach including information on equipment and testing methods. Also described are the various parameters that affected the diffraction loss. Observed diffraction losses showed little dependence on polarization and building material. For diffraction angles greater than 5 degrees, a simple linear equation was fit to the data and accurately describes the diffraction loss. A logarithmic equation describes the dependence at smaller angles. The model developed shows very good agreement with theory and other measurements. Also included are an overview of the fixed wireless industry, a discussion of system design issues, and a review of the historical and mathematical development of diffraction theory. / Master of Science

Yes / In this work, a compact 4-element multiple-input multiple-output (MIMO) antenna system is presented for sub-6 GHz applications. A modified M-shaped strip is used to form each antenna element in the MIMO system. To improve performance, a rectangular-shaped area is etched on the opposite side of each element in the ground plane. The antenna size is 100 × 60 mm2. Most interestingly, the port isolation is improved by rotating the etched areas and the corresponding radiating elements. This one-of-a-kind approach aided in the development of a highly isolated MIMO antenna with a small footprint. The theory of characteristic modes (TCM) is used to analyze the behavior of rotating the etched areas in the ground of the antenna. The antenna provides significant port isolation above 20 dB, stable radiation patterns, and an outstanding ECC of less than 0.01. The design is simple and compact, making it suitable for MIMO operation on handheld devices. / The full-text of this article will be released for public view at the end of the publisher embargo on 6 Jun 2024.