Electro-dynamic analysis of 60mm mortars modified with guidance, navigation, and control components

Abstract

Abstract:This paper summarizes the results from numerical analyses of 60mm mortar projectile bodies that are modified with guidance, navigation, and control (GNC) hardware. The major findings from the study include: 1) the far field radiation patterns predicted for the projectile considered in this analysis are sensitive to the overall size and shape of the projectile flight body, specifically shorter projectile structures tend to radiate more energy in the transverse flight direction, and 2) some electrical characteristics such as the voltage standing wave ratio (VSWR), characteristic impedance (Zo), and the return loss, as seen from the embedded GNC antenna are sensitive to the projectile body size and shape, also shorter projectile structures appear to have lower resonant frequency given the same GNC antenna configuration. The numerical simulations are validated with experimental measurement data obtained from the anechoic chamber. This was true for VSWR, S11 and characteristic impedance data, as well as the far field radiation pattern characteristics. Intro/Background:Technologic advances in precision munitions over the past several years have largely been attributed to the intimate incorporation of high fidelity guidance, navigation and control (GNC) systems and concepts, including that of wireless communications components such as radio frequency (RF) antennas, transmitters, receivers, and global positioning systems (GPS), directly into gun launched projectile structures [1]. Much of the motivation behind this trend has been driven by the need for more precise ballistic fires on long range targets or the very challenging environment of military operations in urban terrain (MOUT). A high degree of leveraging of low cost and readily available commercial technologies has played a critical role in this process. Regarding RF antennas and their associated supporting structures, many of their physical characteristics are generally understood to be highly dependent upon the overarching physical construct and material properties of the platform or flight vehicle in which they are implemented [2]. Of course for gun launched projectiles there are numerous, and somewhat competing design considerations, such as fundamental aerodynamic and thermodynamic behavior that must also be taken into account and ultimately combined with the optimal electro-dynamic characteristics of the projectile guidance and communications system. The results of a study undertaken to further illustrate and quantify the physical behavior, and more specifically the expected variation in performance, of embedded GNC communication antennas for utilization in tube launched guided mortar rounds is described within this report.The use of RF communications systems and circuits for guiding, controlling, and experimentally characterizing gun launched projectiles is well documented [3]. Initially the RF systems used were typically large, power hungry, and often times necessitated significant physical modifications to the projectile body, for example S-ban...

Framework For A Software-defined Global Positioning System (GPS) Receiver For Precision Munitions Applications

“…The minimum power of 26.8 dBW (including GPS satellite antenna gain) of the generated C/A signal is broadcast from the satellite through the atmosphere to the receiver. This loss can be approximated to be the sum of the free space path loss, approximately 182.4 dB, atmospheric loss, 2-3 dB, and receiver antenna gain, +1 dB to < −40 dB (9), which will vary with projectile geometry (11). Therefore, fundamentally, in the optimal scenario, the C/A code at the receiver is approximately −157.4 dBW (−127.4 dBm).…”

“…These software registers within the device provide information regarding waveforms supplied to the GPIF physical pins of the CY7C68013A. Programming of these registers is hard-coded into the device via firmware and the use of a Windows-based GPIF designer tool, GPIFtool.exe (11). Figure 10.…”

A Novel GPS Receiver Algorithm for Continuous Tracking on Spinning Cylindrical Platforms

“…In the past few decades, GPS has revolutionized navigation, positioning, and timing with numerous civilian and military applications. Recently, there is increased interest in GPS navigation for small, metallic cylindrical platforms . These platforms have potentially high rotation rates and short flight times.…”