What are drum like objects in cell phone towers?

Those are antennas. Point to point type. These antennas are highly directive and can haul wireless signals over several kilometers in a very narrow beam.

As antennas are enclosed in a protective gear it can be a bit difficult to know what kind of antenna it is.

To guess the kind of antenna the drum like shape is look at it from behind. If it is tapered towards the end then it is probably a horn. If it is round both front and back then its parabolic. Also the “horn drum” is a lot smaller than parabolic drum. In Fact it looks more like a bulb than a drum.

Both horn and parabola are aperture antennas. Horn uses the principles of waveguide to provide smooth impedance matching (in simple words transition for the signal in wire to the signal in free space aka air).

Whereas a parabolic dish uses the principle of reflection to focus the signal and aggregate into a beam to transmit it to long distance.

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Unlocking the Potential of Carbon for Long-Distance Electrical Transmission

ABSTRACT: We present a technique to manufacture large scale carbon based conductors for transmission of electrical energy over continental scale distances. We start by identifying precursors that could be used for production processes.We review the current manufacturing techniques of producing carbon based fibers and explain why certain precursors have dominated carbon materials industry. We identify methods that can be used to increase the yield through alternative precursors.We put forward a theory of why carbon conductors have less conductivity than metals and what can be done to improve it. Finally we postulate that with cheaper production methods even if carbon based conductors are 10 times less effective than poor metallic conductors like steel, they can still outperform them in High Voltage transmission lines if cheap manufacturing techniques could be developed. INTRODUCTION: Copper and in certain very specific applications aluminium & silicon steels dominate when it co...

Do electrons really flow as a beam in cathode ray tubes?

Abstract: It is generally well accepted that a beam of electrons flow from cathode to anode in a cathode ray tube. Taking pressure data from a variety of sources from CRT manufacturers’ data sheets to engineering documents of large hadron colliders we show through calculations that there is enough residual gas in these devices to form a conducting path from anode to cathode due to plasma formation. When high voltages are applied at the anode the gas is ionized and becomes a plasma forming a ‘wire’ between the two electrodes that causes conduction of energy. The objective of this brief note is to encourage scientists and engineers to re-investigate commonly accepted beliefs about vacuum tubes and develop new knowledge that can revitalize the field especially at a time when nano scaled vacuum channel transistors are being envisioned. Most vacuum tubes have operating pressures in the ultra high vacuum range. This is true for cathode ray tubes, vacuum tu...

Low energy fabrication of a high strength layered ceramic composite for high temperature oxidative environments

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Force calculations on electron in vacuum tubes

ABSTRACT A claim was made in the paper titled “Do electrons really flow as a beam in cathode ray tubes? ” where we asserted that electrons remain near the cathode surface during the operation of CRT. Here we do force calculations on electrons by estimating the debye length of electrons emitted after thermionic emission and show that under given applied voltages if electrons are placed at debye length they are sufficiently far away from the cathode surface to be accelerated towards it. Debye length, while typically used to measure charge screening distance in plasmas and electrolytes, can also be used to estimate the distance of emitted electrons from the cathode surface. In the same way debye length is used to calculate the thickness of an electrical double layer in which the surface charge and charge on inner helmholtz plane are immobile & the charges on outer helmholtz plane are mobile we can model emitted electrons as mobile charges & image charges distributed on the cathode...

Manufacturing technique for layered carbon /ceramic composite for use in high temperature oxidative environment

We previously described a layered carbon glass material system that is different from c/sic , c/sio2 matrix composites in that it consists of a distinct C/C phase which is coated by an sio2 layer. https://akshatjiwannotes.blogspot.com/2024/12/low-energy-fabrication-of-high-strength.html This material system presents a distinct advantage in a high temperature oxidative atmosphere as the C/C matrix is protected by the oxidation resistant glass shield. Such a material can supposedly be synthesized in an open oxidative atmosphere. In this short note we will answer some questions such as What manufacturing technique will be used? How can silica particles be sintered on the substrate? How can adhesion between sintered particles and carbon substrate be ensured? What, if any ,sintering aids will be used? What would be the mechanical properties of the composite so formed? What level of heat treatment will be required? To make the composite only the minimum amount of heat ...

Remarks on the space policy conference 2025

Happy to have participated in the space policy conference, 2025 held in New Delhi. The discussion revolved around spectrum allocation and the use of satellites in meeting the communication needs of tomorrow. The view among the speakers was pragmatic emphasising that while satellite communication will play an important part in the future of networking the role of terrestrial telecommunication will not be diminished especially as new advancements in fiber optics are happening rapidly. I concurred. While wireless communication remains the most important application of space technology I wondered if there is more to it? Can space policy look beyond weather,defense & telecommunication? Not too long ago NASA was doing just that. There was a period of rapid development in materials science ,cryogenics & electronics that influenced industries beyond the space sector. That era was characterised by industrial cross collaboration. New composites were developed ,new synthesis techniq...

Electrostatic Machines in Power Engineering: Rethinking Their Role and Future Potential

ABSTRACT: Although electrostatic motors and generators have been among the first electrical machines developed they have not gained widespread adoption in power engineering.Except for very niche applications in micromotors the electrostatic machines have not done well.The electrostatic theory is overlooked & it's the electromagnetic counterparts that are intensely studied in educational institutes. In this paper we explore the reasons behind this fact & propose the design of an electrostatic generator that can compete with its magnetic analogue. INTRODUCTION: Forces due to electrostatic fields are extremely powerful. If a charge is moving at the speed of 1m/sec then the magnetic force due it is 3x10^8 times weaker than the electrostatic force. This should have encouraged engineers & scientists to develop electrostatic motors & generators but it hides a very important point about electrostatic fields. At the magnetic saturation limit the electric field ...

Engineering Design of a Stirling Engine Integrating High-Temperature Combustion and Low-Temperature Cryogenic Sources

Engineering Design of a Stirling Engine Integrating High-Temperature Combustion and Low-Temperature Cryogenic Sources ABSTRACT While Stirling engine analysis using the ideal adiabatic model improves upon the isothermal model by accounting for heat exchange between hot and cold spaces it comes at the cost of complexity requiring the designer to solve for 16 variables and 22 differential equations. Higher order analysis increases the complexity further by using CFD to analyse the engine. None of these methods answer the basic questions about engine design. In this technical report we develop a set of equations that can help design a Stirling engine from scratch by reverse engineering from the power input and calculating plate area,stroke length,piston velocity and frequency of the engine along with the temperature at the hot end. We use the results to calculate the working volume of the engine and the pressure and temperature at the hot side to drive the output. INTRODUC...

What's with all the H1B ruckus?

The US policy makers are facing some tough choices as there's now an increased competition for talent from places like Europe,Australia,canada and even from asian nations like south korea , singapore ,saudi arabia ,UAE etc. While I'm all for protecting domestic jobs there's the danger that USA may face significant competition in the coming decades from the nations that are eager to hire talented immigrants to build their industry. The solution I think is to take lead in key industries to continue the growth. US did well initially with electric vehicles but it lost advantage. It has a lot going for it in AI and Google's quantum supremacy is promising for US deep tech. In semiconductors the chips and science act did well to promote local industries. US still has one of the largest fiber optic cable manufacturers. It's telecom industry is doing reasonably well. Boeing suffered some setbacks but other aviation components manufacturers like GE are doing well. Th...

Doping strategy for all carbon materials

The challange 1. Carbon is a very small atom. With an atomic number of 6, there are only 5 other atoms that are smaller than carbon. Compared to silicon with an atomic number of 14 the doping choices are minimal. Unlike silicon, elemental carbon can't be melt processed so existing tools & understanding about dopants (or more generally alloying) are out. 2. Carbon has a very rich chemistry. Elements like hydrogen & nitrogen that would become good candidates for doping actually form covalent bonds with carbon[1]. And instead of providing electron-hole pairs, the band gap continuously. Compare this with boron & phosphorus in silicon where they act more or less in their free atomic state. Sure with careful engineering maybe hydrogen & nitrogen can be made to fit inside carbon lattice (nitrogen happily sits inside diamond for example & it would be expected that it would act as a dopant in diamond like carbon as well) 3. The crystal arrangements of carbon that ...

Notes by Akshat Jiwan Sharma

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