Resonance conditions for a substrate-superstrate printed antenna geometry which allow for large antenna gain are presented. Asymptotic formulas for gain, beamwidth, and bandwidth are given, and the bandwidth limitation of the method is discussed. The method is extended to produce narrow patterns about the horizon, and directive patterns at two different angles.

Gain enhancement methods for printed circuit antennas

Abstract. This paper presents a method to derive the ionospheric total electron content (TEC) and to estimate the biases of GPS satellites and dual frequency receivers using the GPS Earth Observation Network (GEONET) in Japan. Based on the consideration that the TEC is uniform in a small area, the method divides the ionosphere over Japan into 32 meshes. The size of each mesh is 2° by 2° in latitude and longitude, respectively. By assuming that the TEC is identical at any point within a given mesh and the biases do not vary within a day, the method arranges unknown TECs and biases with dual GPS data from about 209 receivers in a day unit into a set of equations. Then the TECs and the biases of satellites and receivers were determined by using the least-squares fitting technique. The performance of the method is examined by applying it to geomagnetically quiet days in various seasons, and then comparing the GPS-derived TEC with ionospheric critical frequencies (foF2). It is found that the biases of GPS satellites and most receivers are very stable. The diurnal and seasonal variation in TEC and foF2 shows a high degree of conformity. The method using a highly dense receiver network like GEONET is not always applicable in other areas. Thus, the paper also proposes a simpler and faster method to estimate a single receiver’s bias by using the satellite biases determined from GEONET. The accuracy of the simple method is examined by comparing the receiver biases determined by the two methods. Larger deviation from GEONET derived bias tends to be found in the receivers at lower ( Key words. Ionosphere (mid-latitude ionosphere; instruments and techniques) – Radio science (radio-wave propagation)

Ionosphere and thermosphere: Derivation of TEC and estimation of instrumental biases from GEONET in Japan

Propagation Of Radio Waves

Theory of electromagnetic wave propagation

Understanding and modeling the rainfall drop size distribution is important in a number of applications, in particular predicting and mitigating attenuation of satellite signals in the millimeter band. Various standard statistical distributions have been proposed as suitable models, the first widely accepted being the exponential distribution. Subsequently, gamma and lognormal distributions have been shown to provide better rainfall rate computations. Some empirical studies have revealed bimodal distributions under some circumstances. A natural question to ask therefore is how often gamma and lognormal distributions fit the empirical data. In this paper we fit lognormal and gamma distributions to 1 min slices of rainfall drop size distributions taken from 7 year data from the Chilbolton Observatory in southern England. The chi-square goodness of fit of the models against the data is calculated, and it is found that failure to fit is greater than would normally be expected. This failure to fit is broken down and examined against seasonal variations, different rain rates, atmospheric temperature, and wind speed. Possible reasons for the lack of fit are explored, and alternative fits using models based on Gaussian Mixture Models are developed and found to be an improvement.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2015RS005674

Modeling rainfall drop size distribution in southern England using a Gaussian Mixture Model

Determination of Vertical Total Electron Content (VTEC) and analysis of its diurnal variation is presented for NavIC data The radio waves propagating through the ionosphere suffers from a delay depending upon the frequency of radio wave and Total Electron Content (TEC) This delay affects the positional accuracy of the navigation system The proposed study is used to correct this delay called first order error correction

Study of temporal variation of vertical TEC using NavIC data

During propagation of radio navigational signal through the ionosphere, velocity of radio signal changes due free electrons present in the path between transmitter and receiver. The delay experienced by the signal depends on the Total Electron Content (TEC) of ionosphere as well as frequency of the signal. The delay introduced by ionosphere can degrade the positional accuracy. So, in this paper we would be estimating and smoothing the total electron content from NavIC data in order to derive a proper conclusion out of it. The proposed work can be used for correcting the first order ionospheric error.

Estimation and Smoothing of TEC from NavIC Dual Frequency Data

Data on rain drop size distribution, collected at Ahmedabad, India, has been analysed to develop empirical model on drop size distribution (DSD). Out of the various DSD models available in literature, analysis has been done for lognormal distribution as it has been reported to be suitable for tropical regions. The empirical model has been derived on the basis of fit parameters evaluated from experimental data. It is observed that data fits well in lognormal distribution for Ahmedabad.

http://nopr.niscair.res.in/bitstream/123456789/13320/1/IJRSP%2040%286%29%20330-339.pdf

Modeling of rain drop size distribution for a tropical hot semi-arid site in India

Present study shows the development of integrated rain drop size distribution (DSD) model and gives a comparative study with DSDs of difierent regions in India. This work is useful for estimation of rain induced attenuation. Rain data of flve difierent regions (Ahmedabad, Shillong, Thiruvananthapuram, Kharagpur and Hasan) was used for this work. Attenuation characteristics are difierent for difierent regions because DSD varies according to the climatic conditions. Development of DSD model for each location is not feasible. It is a demand to develop a integrated DSD model which gives the tolerable error in DSD for difierent regions, so that, it can be adjusted in fade margin of the communication system. The result of this work shows the good correlation between the proposed integrated DSD model and DSDs of difierent regions.

/pdf/regional-variability-of-rain-drop-size-distribution-model-in-1xwej2nzmn.pdf

Regional Variability of Rain DROP Size Distribution Model in India

The data on rain drop size distribution, collected at Ahmedabad (India), has been analyzed to develop empirical model on drop-size distribution (DSD). Out of the various DSDs available in literature like Marshall and Palmer, Gamma and lognormal, analysis was carried out for the suitability of lognormal distribution. The lognormal distribution has been found suitable as also predicted by others for Indian climate. The empirical model has been derived on the basis of fit parameters of the distribution evaluated from data.

B. S. Jassal

Papers

Study of temporal variation of vertical TEC using NavIC data

Estimation and Smoothing of TEC from NavIC Dual Frequency Data

Modeling of rain drop size distribution for a tropical hot semi-arid site in India

Regional Variability of Rain DROP Size Distribution Model in India

Modeling of rain drop-size distribution for Indian region