2 edition of A design study of antenna modulation techniques resulting in reduced sidelobe levels found in the catalog.
|Contributions||Naval Postgraduate School (U.S.)|
|The Physical Object|
|Pagination||1 v. :|
5 Antenna Arrays Advantage Combine multiple antennas More flexibility in transmitting / receiving signals Spatial filtering Beamforming Excite elements coherently (phase/amp shifts) Steer main lobes and nulls Super-Resolution Methods Non-linear techniques Allow very high resolution for direction finding. 8 Antenna gain (G) Because an antenna is a passive device, the power radiated can not be greater than the input power. The ability of an antenna to focus electro-magnetic energy is defined by its gain. Antenna gain is expressed as a ra tio of the effective radiated output power (Pout) to the input power (Pin) The gain of an antenna is a measure of power transmitted relative.
design techniques theories that have been demonstrated in many novel investigations where, in order to satisfy the size constraints, the ground plane –where the electronics of the mobile are located- is used as a tool for non-resonant antenna path to improve the radiation pattern. These conditional probabilities are plotted in Figure , but are scaled by the a priori probabilities P 1 the show how the possible voltages v are assigned to the two regions V 1 and V 2 in accord with (). in Figure a the a priori probabilities are equal for the two possible messages, and the decision threshold A/2 given by () falls halfway between zero and A.
65) Which angle of rhombic antenna represents one half of included angle of two legs of one wire? a. Apex angle b. Tilt angle c. Both a and b d. None of the above. ANSWER: Tilt angle. 66) Which among the following is not a disadvantage of rhombic antenna? a. Requirement of large space b. Reduced transmission efficiency. Multiple antenna techniques. Multiple antenna techniques are divided into three subclasses. 1. Diversity Schemes. 2. Smart Antenna Systems (SAS) 3. MIMO Systems. Diversity Scheme. Diversity Scheme is a technique, which is used to improve the signal strength. In diversity scheme, two or more communication channels are used.
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Calhoun: The NPS Institutional Archive Theses and Dissertations Thesis Collection A design study of antenna modulation techniques resulting in reduced sidelobe levels. release and ale; A DESIGN STUDY OF ANTENNA MODULATION TECHNIQUES RESULTING IN REDUCED SIDELOBE LEVELS by Stephen Patrick Leane Lieutenant, United States Coast Guard B.S., United States Coast Guard Academy, Submitted in partial fulfillment for the degree of MASTER OF SCIENCE IN COMMUNICATION ENGINEERING from the UNITED STATES NAVAL POSTGRADUATE SCHOOL December ABSTRACT It is desirable, for many applications, to utilize a receiving antenna system.
A design study of antenna modulation techniques resulting. taneously scanned antenna patterns. A design analysis is presented for a linear array which obtains reduced sidelobe levels by on-off switching of the individual array elements and subsequent filtering of the array output : T S Fong, F G Terrio, W H Kummer, A T Villeneuve.
low sidelobe level (SLL) and sideband levels (SBL) of a time modulated linear antenna array. The approach followed here is not to give fixed level of excitation to the elements of an array, but to change it dynamically with time. The excitation levels of the different array elements over time are varied to get the low sidelobe and sideband : Swaprava Nath, Subrata Mitra.
There are different reduction techniques to reduce the sidelobes of P4 code. Diﬀerences in sidelobe levels, implementation techniques, and Doppler UWB Antenna and Array Design. A design analysis is presented for a linear array which obtains reduced sidelobe levels by on-off switching of the individual array elements and subsequent filtering of the array output signal.
The mainlobe shape and width, as well as the near sidelobe levels, are determined by the wavelength, the antenna reflector size, and the tapering of its illumination. More distant sidelobes are caused by imperfection in the antenna and blockage of radiation by the feed horn, its supports (Fig.
), radome, and so on. revolutionizing the design of millimeter-wave and sub-millimeter-wave transceivers and antennas. In this article, the design of the millimeter-wave integrated antennas is discussed, the concept of near-field direct antenna modulation (NFDAM) is intro-duced, and the implementation of a GHz proof-of-concept chip based on NFDAM is presented.
Antenna design, as reflected in low sidelobe levels, is an ECCM design technique, because it prevents a jammer or deceiver from affecting the radar at many azimuths.
Low sidelobe levels also make the job of antiradiation missiles more difficult, since there is less chance of the missile homing in on the radar unless the radar is pointing at the missile.
antenna noise temperature and B is the bandwidth of the system receiver. G/T Parameter. A convenient figure of merit proportional to the signal-to-noise ratio received by the antenna is the value of G/T, in which G is the antenna gain and T is the receiving system noise temperature in degrees Kelvin.
T is the summation of the antenna noise. An antenna's radiation pattern in the far field is often characterized by it's beamwidth and sidelobe levels.
This introduction to antenas illustrates this with an example. Impedance. Antenna Impedance is presented as the ratio of voltage to current at the antenna's terminals. Low- and High-Frequency models are presented for transmission lines.
Antenna Modeling EZNEC tutorial by Greg Ordy, W8WWV for intermediate users; Comprehensive website of LB Cebik, W4RNL (Silent Key) - requires signup to access (previously free but recently converted to a subscription services with the online magazine), hundreds of useful tutorials, models, and antenna design notes.; Steve Stearns, K6OIK, has published "Antenna.
Antenna Design and Optimization Antenna Model. The antenna system structure on the tag is shown in Figure 4 and is located on the XOY plane. The system consists of three components: a four-element patch antenna array, a feeding network, and a printed LPDA. information includes the antenna gain values, reference radiation patterns, sidelobe requirements, and other technical data.
Thus, this memorandum is a library of the rules, regulations, and. 3. Proposed QAM-based sidelobe modulation Signaling strategy. We have observed that the existing ASK-based DFRC approaches, can only broadcast the same information to all the communication receivers by controlling the sidelobe levels during each radar pulse.
Since the sidelobe level towards all the communication directions is same. angular direction (from antenna pointing) • Signature analysis and inverse scattering: 4. target size (from magnitude of return) 5. target shape and components (return as a function of direction) 6.
moving parts (modulation of the return) 7. material composition • The complexity (cost & size) of the radar increases with the extent. Pulse compression with non-linear frequency modulation has some clear advantages.
For example, it no longer requires amplitude weighting for the suppression of the resulting sidelobes, the so-called time-sidelobes, since the form of modulation already fulfills the function of the otherwise necessary amplitude weighting. A round parabolic dish antenna 2 meters in diameter has a small feed horn that illuminates the dish surface nearly uniformly to the edge.
Estimate the gain and beamwidth at GHz, and estimate the sidelobe levels. Now reduce the sidelobe levels to below 20 dB by changing the dish illumination, and estimate the change in gain and beamwidths.
interference, adaptive self-tuning filter, antenna sidelobe interference canceling, cancellation of noise in speech signals, etc. Computer simulations for all cases are carried out using Matlab software and experimental results are presented that illustrate the usefulness of Adaptive Noise Canceling Technique.
Chapter 6: Radar Antenna 6 - 2 Dr. Sheng-Chou Lin Radar System Design Antenna Pattern Regions •Near-Field (Reactive): Fields are predominantly reactive •Inter-mediate Region (Fresnel): Radiated near field angular dependence is a function of distance from the antenna (i.e., things are still changing rapidly).Antenna Handbook.
The original intent when the first edition was planned was to provide the reader with a practical, yet theoretical, book that could be used with only a minimal effort to actually design and install radio antennas. It was assumed that the readership would possess a wide range of levels of antenna sophistication.Figure Antenna beam solid angle in relation to (a) the antenna pattern and (b) source solid angle There are three standard ways to characterize small thermal sources.
The most complete description is TB(T,I,f) for each of two polarizations, which may be reduced to two average brightness temperatures TB.