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Figure 13(b) shows the improved circuit model and Fig. 14 shows input impedance of the pendulum array prototype, coil and the circuit model plotted across frequency. The peaking of the input impedance indicates a greater portion of the input power is coupled to the pendulum system while the power consumption caused by the Ohmic resonance of coil is relatively reduced. Note that not all the modes were predicted by the circuit model due to the fact the mutual coupling among the pendulum elements are not included in the model demonstrating the superiority and completeness of the full wave model. The estimated Q factor at the in-phase mode is around 62.2 as previously demonstrated using the circuit model. To our knowledge, this is the first time such a high Q factor has been achieved in a mechanical antenna system using magnetic dipoles at ULF, demonstrating the potential of magnetic pendulum arrays for efficient ULF transmission.
As the growth of mobile technology network increasing exponentially due to which radio frequency becomes more valuable natural resources. Shortage of bandwidth creates an enormous opportunities for researchers and engineers for exploration of underutilize millimeter wave spectrum in order to design and develop future technologies. It is a need of an hour to do extensive studies on the impact of millimeter wave technologies as both indoor and outdoor environments. This paper describes the various studies carried out earlier in the field of radio wave propagation at 60 GHz in different outdoor environments.
They use channel sounder which has variable rate PN sequence generator. For 38 GHZ they had 400 Mcps and for 60 GHz they had 750 Mcps. The millimeter wave up down convertor get the input of IF frequency of 5.4 GHz. These convertors contain mixer and LO frequency multipliers which give output of 37.625 and 59.4 GHz. The 38 GHz Tx and Rx used vertically polarized horn antennas with gain of 25 dB and half power beam width of 7. The 60 GHz Tx and Rx used vertically polarized antenna whose gain is 25 dB and contain beam width of 7.3.
The TX used in this was consisted of SMF100A microwave signal generator of 10 GHz frequency which was attached to frequency multiplier SMZ90 which multiplies by 6. Then it was connected to V-Band horn antenna of 24dBi gain and 11 beam width. The RX system consisted of same antenna system used in TX. It was then connected to low noise amplifier NIZ-3387. The signal was then sent to harmonic mixer FS-Z90. Then signal was down converted and sent to vector signal analyzer FSQ26.
For measuring the effect of rain of radio wave propagation especially at 60 GHz the studies are carried out by Walther et al [17] at two different sites namely UK and Singapore. They have obtained the data from the Rutherford Application Laboratory (RAL) located in southern part of England. Rain rate and drop size distribution was parameters used by them. Rain rate was observed from rain gauge and DSD was obtained from impact type drop size disdrometer, RD-69.
The studies done by Simon et al. [19] for calculating effects of vegetation on radio wave propagation at 60 GHz. The parameters used by them are cumulative density function and probability density function and compared them against different present models. The experimental setup was explained in [19].
The experiment was performed at various sites. The first site contains 3 foliated maple trees and one foliated flowering crab tree. The link distance was 63.9 m. Second site consists of several spruce and one pine tree in a row which resembles a wall. The link distance was 110 m. The third site consists of leafless maple tree and one leafless flowering crab tree. The link distance was 63.9 m. The result obtained from all the three experimental sites shows that the extreme value and lognormal model best fits the RF attenuation characteristics between trees. It was observed from experiment that propagation at 2 and 60 GHz was frequency and wind speed dependent. The attenuation observed through tree was larger when size of obstruction lies in the foliated path and wavelength are similar in size. The values of AFD and LCR were statistically modeled.
A simulation model was developed by Michael et al. [20] for studding effects of vegetation on radio wave propagation. In this model they have generated signal fading caused by swaying vegetation by using multiple mass spring model which represent tree and turbulent wind model. Different parameters used in this model are cumulative distribution function (CDF), level cross rate (LCR), auto correlation function (ACF) and average fade rate (AFR). Similarities between results obtained from this model and experiment results from [19] were observed.
Ladder frame structures are used as models for multistorey buildings. These periodic structures exhibit alternating propagating and attenuating frequency bands. Of the six different wave modes of propagation, two modes strongly attenuate at all frequencies. The other four modes have nonoverlapping stop band characteristics. Thus, it is challenging to isolate such structures when subjected to broadband, multimodal base excitation. In this study, we seek to synthesize a periodic ladder frame structure that has attenuation characteristics over the maximal range of frequencies for all the modes of wave propagation. We synthesize a unit cell of the periodic structure, which comprises two distinct regions having different inertial, stiffness, and geometric properties. The eigenvalues of the transfer matrix of the unit cell determines the attenuating or the nonattenuating characteristics of the structure. A novel pictorial presentation in the form of eigenvalue map is developed. This is used to synthesize the optimal unit cell. Also, design guidelines for suitable selection of the design parameters are presented. It is shown that a large finite periodic structure comprising a unit cell synthesized using the present approach has significantly better isolation characteristics in comparison to the homogeneous or any other arbitrarily chosen periodic structure.
PHASE II: Based on the results of Phase I efforts and the Phase II Statement of Work (SOW), develop, demonstrate, and deliver a prototype low SWaPe mmWave 6G radio transceiver using integrated microwave photonics. The working prototype must address technical risks, validate the draft specifications, and demonstrate the functionality of the overall design. Develop, demonstrate, and deliver a prototype low SWaPe mmWave 6G radio transceiver using integrated microwave photonics at 60GHz or higher. The transceiver should demonstrate greater than 10 percent fractional bandwidth. The working prototype must address technical risks in developing integrated high speed linear optical modulators and high speed photodetectors, and their integration with millimeter electronics and swap antenna. The working prototype must demonstrate 6G base-station operation with >10Gbps up/down link throughputs. The Phase II work should also demonstrate a clear path for achieving future 6G operation at 200GHz band.
Electrostriction in an optical fiber is introduced by the interaction between the forward propagated optical signal and the acoustic standing waves in the radial direction resonating between the center of the core and the cladding circumference of the fiber. The response of electrostriction is dependent on fiber parameters, especially the mode field radius. A novel technique is demonstrated to characterize fiber properties by means of measuring their electrostriction response under intensity modulation. As the spectral envelope of electrostriction-induced propagation loss is anti-symmetrical, the signal-to-noise ratio can be significantly increased by subtracting the measured spectrum from its complex conjugate. It is shown that if the transversal field distribution of the fiber propagation mode is Gaussian, the envelope of the electrostriction-induced loss spectrum closely follows a Maxwellian distribution whose shape can be specified by a single parameter determined by the mode field radius.
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