ISRO Research Articles

Preface

Proceedings 1st International Conference on Intelligent and Sustainable Power and Energy Systems (ICISPES 2023) 26 - 27 September, 2023 About the Conference The “1st International Conference on Intelligent and Sustainable Power and Energy Systems (ICISPES 2023)” is aimed to address the state-of-the-art multidisciplinary research needs and interdisciplinary aspects of intelligent and sustainable technologies in power and energy systems in the form of research papers from industry, faculty, research scholars, and PG/UG students, along with keynote lectures and a number of invited talks from reputed speakers. The ICISPES 2023 aims to provide a platform to present their work to share experiences and ideas in the areas of Renewable Energy, Electric Transportation, Power Electronics, Electric Drives, Control Techniques, Smart Grids, Communication Protocols, Intelligent Charging Infrastructure and Standards, machine learning, artificial intelligence, big data analytics, IoT, etc. In view of the changing scenario under intelligent and sustainable power and energy, this conference aims to put together the experts from these areas to disseminate their knowledge and experience for working in years to come.The ICISPES provides an international platform for all research scholars, practitioners, academicians, students and scientists to discuss and exhibit the latest research developments and discoveries in intelligent and sustainable technologies. This conference enables us to share and exchange research knowledge and ideas in power and energy systems. About the Institution Dayananda Sagar College of Engineering is approved by the All-India Council for Technical Education (AICTE), Govt. of India and affiliated to Visvesvaraya Technological University, Belgaum, Karnataka. It has the widest choice of Engineering branches, having 20 undergraduate courses and 06 postgraduate courses. In addition, it has 20 research centres in different branches of Engineering catering to research scholars for obtaining a PhD under VTU. Various courses are accredited by the NBA. The Institute is spread over 23 acres of land with a requisite infrastructure supported by laboratories with state-of-the-art equipment and machines. The central library, with modern facilities and a digital library, provides the knowledge base for the students. The college has good faculty strength with the highest professional integrity and commitment to academics with transparency in their actions. The faculty members are research-oriented, having a number of sponsored R&D projects from different agencies such as the Department of Science & Technology, Defense R&D organizations, Indian Space Research Organization, AICTE, etc.List of Speakers, Organizing Committee is available in this Pdf.

Exploring the drivers and facets of culture in the formative stage of a public-funded R&D organisation

Culture is critical in organisations, particularly in research and development (R&D) activities. This study explores the facets and drivers that facilitated culture formation in an R&D setting. We focus on the Indian Space Research Organisation (ISRO), which had been able to develop closely guarded space technology indigenously. Based on in-depth interviews with a unique set of respondents in the age range of 66–94 years, we present a holistic organisational cultural model by juxtaposing its facets and drivers. We further expound on how the constraints of the public-funded organisation are negotiated in building a conducive culture.

Multi-mission, multi-sensor study of the Shackleton Crater constrained for volatiles with emphasis on albedo distribution of the Lunar South Pole

Shackleton Crater on the Moon is named in honor of a pivotal figure of the Heroic Age of Antarctic Exploration Sir Ernest Henry Shackleton. The Crater was formed about 3.6 billion years ago at the Lunar South Pole. Due to the low (1.5°) tilt of the lunar axis of rotation, the interiors of the crater receive almost no direct sunlight and observations by passive hyperspectral sensors are only possible due to reflected light. Active sensors are however able to illuminate the interior surface of the crater and make observations. Here we present the results of study of the crater using data from multiple sensors onboard two missions of Indian Space Research Organization (ISRO) and National Aeronautics and Space Administration (NASA). Hyperspectral observations from Moon Mineralogy Mapper (M3) on-board Chandrayaan-1, temperature from Diviner Lunar Radiometer Experiment (DLRE), albedo from Lunar Orbiter Laser Altimeter (LOLA) and Off/On band ratios from Lyman-Alpha Mapping Project (LAMP) on board Lunar Reconnaissance Orbiter (LRO) have been used. Permanently Shaded Regions (PSRs) are identified and Shackleton has been found, as reported, to be a PSR. Emphasis has been laid on LOLA albedo analysis of lunar south pole (80°-90° South). It is observed that the Shackleton Crater exhibits significantly higher albedo compared to its surrounding regions. Some regions exhibit albedo even higher than the Shackleton Crater in the lunar south pole region. The findings of high albedo, coupled with high Off/On band ratio of LAMP, extremely low DLRE temperatures in the permanently shaded regions and detection of hydration features in the M3 hyperspectral data suggests higher probability of hydration in the Shackleton Crater.

DMD Based Multi-Object Spectrograph for INdian Spectroscopic and Imaging Space Telescope: INSIST

INdian Spectroscopic and Imaging Space Telescope (INSIST) is the next-generation UV-Optical space mission proposed by the Indian Astronomical community motivated by the great success of India’s first multi-wavelength Astronomical satellite (ASTROSAT) where Ultra Violet Imaging Telescope (UVIT) was one of the main payload launched in 2015 by Indian Space Research Organisation. INSIST is primarily designed for photometry observation in three bands (g-[400[Formula: see text]nm–550[Formula: see text]nm], u-[300[Formula: see text]nm–400[Formula: see text]nm] and UV-[150[Formula: see text]nm–300[Formula: see text]nm]) simultaneously over 0.25 sq.degree field of view. INSIST is equipped with a low resolution [[Formula: see text]] spectrograph for multi-Object slitless spectroscopy over the imaging field of view and also has a medium resolution [[Formula: see text]] spectrograph for multi-object slit spectroscopy in UV-band over ∼6 sq.arcmin sky. MEMS-based Digital Micromirror Device [DMD] is used to form configurable slits for the selection of objects at the focal plane of the telescope for multi-object slit spectrograph. Multi-Object spectrograph with DMD as a re-configurable slit for INSIST is designed and the performance of the spectrograph is presented.

Chandrayaan-3 Mission: Decoding the Culture and Leadership at ISRO

While organisation culture is crucial for innovation to foster, leadership is the key to promoting a conducive culture. In the present study, I focused on the Indian Space Research Organisation (ISRO), to understand the facets of an innovation-led organisation and the role of leadership. Based on in-depth interviews with a unique set of respondents within the age range of 66–94 years, I pulled out the facets of ISRO culture. I further explored the leadership qualities that enable the formation of such a culture.

A bibliometric study of research output of ISRO's space science and exploration missions

Chandrayaan-1 and Chandrayaan-2, the Indian Mars Orbiter Mission (MOM), and a multi-wavelength astronomical observatory (AstroSat) are the missions launched by the Indian Space Research Organisation (ISRO) under the broader category of space science and exploration. The results generated from the periodically released data from these missions, are published in the form of journal articles, conference papers, The Astronomer's Telegrams, GRB Coordinates Network circulars, etc. The goal of this study is a bibliometric analysis of 592 journal articles on ISRO's four space science and exploration missions which were published between 2002 and 2021 (20 years). The Web of Science Core collection database and Google Scholar are used to retrieve the data needed for the study. Bibliometric indicators like mission-wise distribution of articles; year-wise distribution of articles, relative growth rate and doubling time of publications; prolific authors; leading institutions; international collaboration; highly ranked journals; highly cited articles and keyword occurrences were considered for analysis. The doubling time of publications of those missions which yielded the highest number of articles were separately calculated using an exponential equation and built in algorithms in Python. Advanced data visualization tool such as VosViewer was used for generating the network maps. The bibliometric analysis revealed the usage of mission output data not only by ISRO scientists but also by academia, research labs, etc. Overall, the study can be considered as a comprehensive reference source for information on research trends related to the four Indian space science and exploration missions.

Indian National Education Policy: The Knowledge and Understanding of Secondary School Teachers in West Tripura District

The quality of a nation depends on the quality of its people and the quality of education the people receive. Education is the main structure of the country’s socio-economic development. The development of society and the education system are closely related. A demographic and modern welfare state has considered the responsibility of spreading education as a national task because democracy is based on the development of the education of the people of a country. Different countries provide different education based on tradition and culture and adopt different stages of school and college education to be effective.
 India’s National Education Policy (NEP 2020), approved by the Indian Union Cabinet on July 29, 2020 based on the recommendations of an expert committee headed by Dr. Kasthuriranjan, former Chairman of the Indian Space Research Organization (ISRO). It replaced the National Policy on Education of 1986. The aim of the policy was to create an education system rooted in Indian values that would directly contribute to the transformation of India by providing quality education to all, thus making India a global educational power.
 The current study is conducted in West Tripura District High Schol to analyze the perception of NEP -2020 among teachers. This study will help to increase awareness of NEP-2020 among secondary school teachers and provide teachers NEP 2020 awareness program accordingly for its successful implementation.

Validation of Paras3d Rans Pressure Data with Flight Results Over a Wing-body Rlv Configuration at Supersonic High Angle of Attack Conditions

Winged Reusable Launch Vehicle - Technology Demonstrator (RLV-TD) was successfully flight tested by Indian Space Research Organisation (ISRO). One of the main objectives of this Hypersonic Experiment (HEX) mission is to validate the aerodynamic design and ground based aerodynamic data generation procedure. In this paper, comparison of flight data and CFD estimated pressure coefficient (Cp) over fuselage, wing, vertical tail and rudder are presented at supersonic Mach number and high angle of attack conditions. PARAS3D RANS solver is able to capture the trends as measured in flight. In general, PARAS3D CFD over predicted the compression on windward side and under predicted leeward expansion as compared to flight measurement. In general, CFD predicts Cp close to flight measured value, except over a port in the vertical tail.

Precise Absolute Velocity Estimation of Human Space Flight In Leo Using Navic Doppler Shift Measurements

The Low Earth Orbit (LEO) is the most significant for diverse applications like imaging, human space flight and scientific observations; the number of satellites in LEO is ever increasing. To estimate the Position and Velocity (PV) conventionally multiple ranging sessions are conducted. It increases burden on the ground support staff and computation delays are introduced. These delays will lead to inaccurate estimation errors. Additionally, propagation errors are introduced into the PV estimation. Also, for human space flight applications, safety is of utmost importance, and hence precise and instantaneous determination of orbital parameters is crucial. This makes autonomous determination of the position and velocity of the satellite a necessity on board. In this study, it is proposed to use indigenously developed NavIC (Navigation by Indian Constellation) by Indian Space Research Organization Doppler shift measurements, for precise kinematic estimation of absolute velocity and receiver’s clock bias rate of the human space flight. The novelty of this research work is the usage of the NavIC Doppler shift measurements, for precise kinematic absolute velocity and receiver clock bias rate estimation, for the orbit of the human space flight in LEO, for the first time. This will extend the footprints of indigenously developed navigation technology to space applications. Extensive simulation and analysis is performed to study the Doppler collision at LEO. Thus establishing the suitability of the method, as the LEO will not exhibit Doppler collision unlike on ground. The mean value and Standard Deviation (SD) values of the velocity estimation error are [-0.0027 -0.0001 -0.0045] m/s and [0.1191 0.3550 0.1319] m/s respectively for the best case. The mean and 3-σ standard deviation of clock bias rate estimation error are 0.00075 m/s and 0.6 m/s respectively when the number of visible satellites is six. Additionally, simulations are carried out for a highly inclined sun synchronous orbit; with nominal and 50% higher standard deviation receiver noise, in Doppler measurements. The performance of velocity and clock bias rate estimation error is consistent for different orbits. However, the performance degrades with higher receiver noise.

Characterizing and Mapping Volcanic Flow Deposits on Mount St. Helens via Dual-Band SAR Imagery

Mapping volcanic flow deposits can be achieved by considering backscattering characteristics as a metric of surface roughness. In this study, we developed an approach to extract a measure of surface roughness from dual-band airborne Synthetic Aperture Radar (ASAR) backscattering data to characterize and map various volcanic flow deposits—namely, debris avalanches, lahars, lava flows, and pyroclastic density currents. We employed ASAR and Indian Space Research Organization (ISRO) airborne SAR datasets, from a joint project (ASAR-ISRO), acquired in December 2019 at 2 m spatial resolution, to assess the role and importance of incorporating dual-band data, i.e., L-band and S-band, into surface roughness models. Additionally, we derived and analyzed surface roughness from a digital surface model (DSM) generated from unoccupied aircraft systems (UAS) acquisitions using Structure from Motion (SfM) photogrammetry techniques. These UAS-derived surface roughness outputs served as meter-scale calibration products to validate the radar roughness data over targeted areas. Herein, we applied our method to a region in the United States over the Mount St. Helens volcano in the Cascade Range of Washington state. Our results showed that dual-band systems can be utilized to characterize different types of volcanic deposits and range of terrain roughness. Importantly, we found that a combination of radar wavelengths (i.e., 9 and 24 cm), in tandem with high-spatial-resolution backscatter measurements, yields improved surface roughness maps, compared to single-band, satellite-based approaches at coarser resolution. The L-band (24 cm) can effectively differentiate small, medium, and large-scale structures, namely, blocks/boulders from fine-grained lahar deposits and hummocks from debris avalanche deposits. Additionally, variation in the roughness estimates of lahar and debris avalanche deposits can be identified and quantified individually. In contrast, the S-band (9 cm) can distinguish different soil moisture conditions across variable terrain; for example, identify wet active channels. In principle, this dual-band approach can also be employed with time series of various other SAR data of higher coherence (such as satellite SAR), using different wavelengths and polarizations, encompassing a wider range of surface roughness, and ultimately enabling additional applications at other volcanoes worldwide and even beyond volcanology.

Estimating snow accumulation and ablation with L-band interferometric synthetic aperture radar (InSAR)

Abstract. Snow is a critical water resource for the western United States and many regions across the globe. However, our ability to accurately measure and monitor changes in snow mass from satellite remote sensing, specifically its water equivalent, remains a challenge. To confront these challenges, NASA initiated the SnowEx program, a multiyear effort to address knowledge gaps in snow remote sensing. During SnowEx 2020, the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) team acquired an L-band interferometric synthetic aperture radar (InSAR) data time series to evaluate the capabilities and limitations of repeat-pass L-band InSAR for tracking changes in snow water equivalent (SWE). The goal was to develop a more comprehensive understanding of where and when L-band InSAR can provide SWE change estimates, allowing the snow community to leverage the upcoming NASA–ISRO (NASA–Indian Space Research Organization) SAR (NISAR) mission. Our study analyzed three InSAR image pairs from the Jemez Mountains, NM, between 12 and 26 February 2020. We developed a snow-focused multi-sensor method that uses UAVSAR InSAR data synergistically with optical fractional snow-covered area (fSCA) information. Combining these two remote sensing datasets allows for atmospheric correction and delineation of snow-covered pixels within the radar swath. For all InSAR pairs, we converted phase change values to SWE change estimates between the three acquisition dates. We then evaluated InSAR-derived retrievals using a combination of fSCA, snow pits, meteorological station data, in situ snow depth sensors, and ground-penetrating radar (GPR). The results of this study show that repeat-pass L-band InSAR is effective for estimating both snow accumulation and ablation with the proper measurement timing, reference phase, and snowpack conditions.

Impact of different land use data on WRF model short range forecasts during pre-monsoon and monsoon seasons in India

This study focuses to analyse the impact of land use changes on short range weather forecasts over Indian region. Weather Research and Forecasting (WRF) model simulation experiments are conducted by using land use data from Moderate Resolution Imaging Spectroradiometer (MODIS) and Indian Space Research Organization (ISRO) satellites for pre-monsoon and monsoon season. MODIS 2001 land use is used in control (CNT) experiment and updated land use with recent urban class from MODIS (EXP1) and ISRO (EXP2) for the year 2019 is used to generate model lower boundary conditions in other two experiments. Quantitative error measures and skill score computed for rainfall forecast showed that model skill is better with the use of realistic recent land use data from MODIS and ISRO during pre-monsoon and monsoon period. Extreme Dependency Index score computed also revealed that model skill in predicting extreme rare rainfall events is improved with recent landuse data. Model simulated surface meteorological variables and profiles at lower levels also found to be improved with the inclusion of realistic land use class from MODIS and ISRO. Between the two experiments, the one which used ISRO based land use showed larger improvement particularly during the monsoon season.

Enhancing satellite‐to‐ground communication using quantum key distribution

AbstractClassical Cryptography has been in use for a long time. It has been the only way of securing people's communication. However, there are some flaws observed during the execution of classical cryptography. One of them being the staunch belief that the number composed of multiplication of two large prime numbers cannot be factorised easily, which is under a threat thanks to the computational power of the quantum computers. The next flaw is the non‐detection of the hacker, both of which can be eliminated by using quantum mechanical principles for encryption purposes, which is known as quantum cryptography. Quantum Key Distribution, which provides an information‐theoretically safe solution to the key exchange problem, is the most well‐known example of quantum cryptography. The benefit of quantum cryptography is that it makes it possible to perform a variety of cryptographic operations that have been demonstrated or are hypothesised to be impractical when using solely traditional (i.e., non‐quantum) communication. Free‐space quantum communication has been successfully demonstrated across 300 m by the Indian Space Research Organization (ISRO) in March 2021. With this, ISRO is trying to achieve the same using a satellite‐based communication mechanism, which would revolutionise the mode of modern communication. It is justified that the key generation rate depends on factors like the aperture diameter of the sender and receiver, distance between them, the quantum bit error rate, and many more. The results vary with the parameters in the discussion as explained in the upcoming sections. The avenue of different types of losses that occur while transmitting at large distances, such as Atmospheric Loss, Pointing Loss and Geometric Loss, is explored.

Analysis and design of control systems via parameter‐based approach

Analysis and design of control systems via parameter‐based approach

Generation of Non-Linear Technique Based 6 Hourly Wind Reanalysis Products Using SCATSAT-1 and Numerical Weather Prediction Model Outputs

We combined observations of ocean surface winds from Indian SCATterometer SATellite-1 (SCATSAT-1) with a background wind field from a numerical weather prediction (NWP) model available at National Centre for Medium-Range Weather Forecast (NCMRWF) to generate a 6-hourly gridded hybrid wind product. A distinctive feature of the study is to produce a global gridded wind field from SCATSAT-1 scatterometer passes with spatio-temporal data gaps at regular synoptic hours relevant for forcing models and other NWP studies. We are following the concept from the modern particle filter technique, which does not represent the model probability density function (PDF) as Gaussian. We generated the 6-hourly hybrid winds for 2018 and validated them using the wind speed from daily gridded level-4 SCATSAT-1 winds (L4AW), Cross Calibrated Multi-Platform (CCMP) dataset and global buoy data from National Data Buoy Centre (NDBC). The results suggest the potential of the technique to produce scatterometer winds at the desired temporal frequency with significantly less noise and bias along the swath. The study shows that the generated hybrid winds are of prime quality compared with the already existing daily products available from Indian Space Research Organization (ISRO).

India-Israel Strategic Cooperation: Implications for Pakistan

India and Israel have engaged themselves in advanced military and strategic partnerships which are modernizing and improving from time to time. Both partner states have initiated cooperation in many areas such as space, cyberspace, and many other areas of defense. The Indian space program in partnership with Israel is acquiring modern means and it will give the Indian military, a dominant position in the conflict-prone region of South Asia where the Indian hegemony is challenged by Pakistan. The intelligence sharing and modernizing of the Indian military will help India to acquire advanced technology for the contemporary combat environment. This paper argues that India already enjoys superiority in South Asia and Indo-Israel strategic partnership will create a strategic imbalance. Moreover, this strategic imbalance will compel Pakistan to look for countermeasures.

Deterrence under Surveillance: Indian Space-based ISR Capabilities and Pakistan’s Nuclear Deterrence

India is rapidly building up its space-based Intelligence, Surveillance and Reconnaissance (ISR) capabilities. Although Indian military assets in space are in contention to Chinese space program, they are expected to make Pakistan apprehensive about the future of its nuclear deterrence. Pakistan acquired nuclear weapons to deter its much larger and stronger archnemesis India from violating its territorial integrity. Pakistan’s nuclear deterrence and strategy is aligned with the Perfect Deterrence Theory, a diversion from Classical Deterrence Theory used in the understanding of deterrence relationship between the USA and USSR during the Cold War. The study addresses the impact of India’s space-based ISR capabilities on Pakistan nuclear deterrence and posture. The growth of Indian military space program along with its great interest and investment in supersonic cruise missiles and ballistic missile defense program indicates that India is building up its First Strike potential against Pakistan’s strategic assets and installations. The developments will have a tremendous impact on deterrence stability in South Asia as it will increase the likelihood of a nuclear escalation in future.

An overview of the design and development of lunar rover (Chandrayaan-2) for space applications

The paper gives an brief overview of the design and development of lunar rover (Chandrayaan-2) for space applications. The Moon has always been the center of attention for mankind, more than any other heavenly body in More than any other heavenly body in the night sky, the Moon has long been the focus of human interest. The Moon has always presented mankind with a challenge to learn more about it and to marvel at its wonders because it bears the early history of the solar system. We can uncover the early evolution of the solar system and that of planet Earth by having a better understanding of the Moon. With the 2008 launch of the Chandrayaan-1 orbiter mission to the Moon, India's planetary exploration program was launched by the Indian Space Research Organization (ISRO). India launched Chandrayaan-2, its second lunar exploration mission, nearly twelve years after its first lunar exploration mission. Chandrayaan-2, India's most technologically advanced aircraft, is on an unprecedented mission. The South Polar Region of the Moon will be studied by India's second lunar trip, which will draw on nearly ten years of scientific and Engineering advancement. A major accomplishment for both India and humanity, Chandrayaan-2 was the first mission ever to be sent to the southern pole of the moon. Both the high cold and constant darkness in this area make it extremely unsafe and have a bad impact on missions. India faced a tremendously difficult assignment as a result, and the entire world was interested in its outcome. Chandrayaan-1's eleven remote-sensing scientific instruments from ISRO, NASA, and ESA have made important discoveries, such as the identification of a water signature, the discovery of spinel minerals, lunar lava tubes, signs of recent volcanism, impact-triggered boulder movements, and the detection of sputtered atomic oxygen and backscattered helium on the lunar surface. Three components made up Chadrayaan-2: an orbiter, a lander, and a rover. 2019 saw the launch of this mission. During this mission, the Orbiter was successful in reaching the moon's orbit, but communication with the Lander was lost, which caused Lander to perform poorly and crash with the Pragyan rover and other scientific equipment. The work given here is a mini-project that is taken up as a part of the curriculum completed by electronics and communication engineering students in the second year of the electronics & communication engineering department at Dayananda Sagar College of Engineering in Bangalore.

An Advanced Ku-Band Fine-Resolution and High-Sensitivity Wind Scatterometer

An advanced Ku-band pencil-beam Scatterometer has been developed having a scanning 1.4m diameter Cassegrain antenna, for providing 3km x 20km (for HH beam) and 3km x 23km (for VV beam) fundamental range-slice resolution, a marked improvement over its predecessor Scatsat-1, which provided 6km x 46km (for HH beam) and 6km x 70km (for VV beam). This instrument will carry forward the legacy of data services from the Indian Space Research Organization’s OScat (Oceansat-2 Scatterometer, which operated in orbit from 2009 to 2014) and Scatsat-1, which operated from September 2016 to April 2021, with improved spatial resolution, noise-equivalent normalized radar cross-section (NEσ°) and the sensitivity parameter Kp. The improvement in NEσ° and in the Signal-to-Noise Ratio (SNR) is of the order of 4.5dB, and of Kp by 2.5dB over a Scatsat-1 equivalent resolution cell. Equivalently, over its own range-slice resolution, the new sensor will match Scatsat’s measurement sensitivity. This article elaborates on the system design of the instrument, the performance improvements over Scatsat-1 and the payload characterization methods.

Hexagonal-Triangular Combinatorial Structure Based Dual-Band Circularly Polarized Patch Antenna for GAGAN Receivers

A multilayer gap-coupled dual band hexagonal microstrip patch antenna is presented for GPS Aided GEO Augmented Navigation (GAGAN) receivers. GAGAN is developed by AAI (Airport Authority of India) and ISRO (Indian Space Research Organization) exclusively for aviation purposes with the GPS frequencies L5 (1176.45 MHz) and L1 (1575.42 MHz). The proposed GAGAN antenna has three trapezoidal and four equilateral triangular patch resonators configured to form a gap-coupled hexagonal patch on the top layer and seven equilateral triangular patches with slots in between to form the middle layer. Both the layers are fed by a single coax feed to achieve a dual band compact microstrip antenna of size 55 mm x 55 mm x 3.2 mm. Instead of designing the hexagonal antenna conventionally from a circular patch antenna, the sides of the equilateral triangular patch are truncated to obtain the proposed compact hexagonal antenna as the triangular antenna occupies less area when compared to circular or square patches for a fixed frequency. To bring in novelty with improved performance, the combinatorial structured configuration has been explored through step-by-step optimization. The aspects of GAGAN requirements like circular polarization with a single input, dual band operation and high gain with gain flatness are achieved with this compact structured antenna when compared to square and circular patch antennas. The combinatorial structures such as perturbation and truncation introduced in the patches are responsible for exciting two near-degenerate orthogonal modes producing circular polarization (CP). A cross slot etched in the center patch results in gain enhancement with a gain above 3.2 dBi over a bandwidth of 20 MHz in both the bands. Five shorting pins are added to achieve high impedance matching and good CP with an axial ratio (AR) below 2 dB. The simulated and measured results are found to be in good agreement with greater than 20 MHz operational bandwidth exhibiting CP with an omni-directional radiation pattern having high cross polar levels of -22 dB. The size reduction achieved in the proposed design is 56.79% when compared to the conventional hexagonal patch antenna. The measured 10 dB impedance bandwidth is 2.7% and 2.1% for L5 and L1 bands respectively with a 3 dB AR bandwidth of 2.3% for L5 and 2.0% for L1, satisfying GAGAN requirements.