Description:
FIELD OF THE INVENTION
The present invention relates to the field of electronics and communication engineering, specifically to radio frequency (RF), microwave, and antenna engineering. More particularly, it pertains to a sub-miniaturized loop antenna utilizing a high permeability cylindrical ring type ferrite core, designed for Very Low Frequency (VLF) to S-BAND tactical communication applications. This invention addresses the need for compact, efficient, and wideband antennas suitable for various tactical communication platforms.

Application
The sub-miniaturized loop antenna described herein is applicable in a wide range of tactical communication systems, including but not limited to:
• Ground-based communication terminals, where compact and efficient antennas are required for reliable signal transmission and reception across multiple frequency bands.
• Submarine communication systems, where the antenna's ability to operate effectively in challenging environments is critical for maintaining secure and stable communication links.
• Mobile and portable communication devices used in military and defense operations, where the antenna's miniaturized form factor and wideband capabilities enhance operational flexibility and performance.
• Industrial and commercial applications requiring robust and high-performance antennas for RF and wireless communication over a broad frequency range, from VLF to S-BAND.
The invention's unique design, which eliminates the need for a matching circuit at low frequencies and achieves significant miniaturization, makes it particularly suitable for applications where space and weight constraints are critical considerations.

BACKGROUND OF THE INVENTION
In the realm of electronics and communication engineering, antennas play a pivotal role in facilitating wireless communication by transmitting and receiving electromagnetic signals. Loop antennas, in particular, are widely used due to their simplicity and effectiveness in various applications. These antennas can be classified into electrically large and electrically small categories, with the latter being favoured for applications where space constraints are critical.

Electrically small loop antennas, however, face inherent challenges such as low radiation resistance and limited bandwidth. To overcome these issues, traditional designs often resort to increasing the loop's circumference or the number of turns, which can lead to increased size and complexity. Additionally, achieving impedance matching over a wide frequency range typically necessitates the use of matching circuits, further complicating the antenna design and integration.

In tactical communication systems, where reliability, compactness, and wideband operation are paramount, these limitations pose significant challenges. Existing solutions in the prior art have primarily focused on enhancing the antenna factor to improve performance, but they often fall short in addressing the need for miniaturization and efficient operation across multiple frequency bands.

The present invention seeks to address these challenges by introducing a sub-miniaturized loop antenna that leverages a high permeability cylindrical ring type ferrite core. This innovative approach not only enhances the magnetic field within the loop, thereby increasing radiation resistance, but also enables the antenna to operate efficiently over a broad frequency range from Very Low Frequency (VLF) to S-Band eliminating the need for complex matching circuits and reducing the overall size. The invention offers a robust solution for modern tactical communication needs.

Prior Art Problems

In the field of tactical communication, antennas are critical components for ensuring reliable signal transmission and reception across various frequency bands. Traditional loop antennas, while effective, often face challenges related to size, weight, and bandwidth limitations. Electrically small loop antennas typically exhibit low radiation resistance, which can lead to inefficient performance and limited operational range. Additionally, achieving impedance matching over a wide frequency range often requires complex matching circuits, which can increase the size and complexity of the antenna system.

Prior Art Disadvantages

Existing solutions in the prior art primarily focus on enhancing the antenna factor to improve shielding effectiveness, but they often fall short in addressing the need for miniaturization and wideband operation. Many conventional antennas require multiple interconnections and complex matching circuits, which can lead to issues such as intermittent connections, misalignment, and increased susceptibility to environmental factors. These limitations hinder the deployment of antennas in compact and mobile tactical communication systems.

Technical Solution of the Present Invention

The present invention provides a sub-miniaturized loop antenna utilizing a high permeability cylindrical ring type ferrite core. This innovative design enhances the magnetic field within the loop, significantly increasing radiation resistance and enabling efficient operation across a broad frequency range from 10 kHz to 3 GHz. The antenna features a multi-turn loop circuit printed on a flexible dielectric substrate, eliminating the need for traditional coil wrapping and complex matching circuits. The use of an industrial-grade PCB ensures structural rigidity and reliable performance.

Technical Effect

The technical effect of the present invention is the achievement of a highly miniaturized antenna with dimensions less than 0.000005×λ at 10 kHz, while maintaining excellent impedance matching and gain characteristics over a multi-octave bandwidth. The antenna's design allows for stable and reliable communication without distortion, even in challenging environments, making it ideal for tactical applications.

Technical Advancement

The invention represents a significant technical advancement by combining high permeability materials with a novel loop configuration to achieve miniaturization and wideband performance without the need for additional matching circuits. This advancement simplifies the antenna design, reduces the overall system complexity, and enhances the antenna's suitability for modern tactical communication systems.

Need for the Present Invention

There is a growing need for compact, efficient, and wideband antennas in tactical communication systems, driven by the increasing demand for mobile and portable communication solutions. The present invention addresses this need by providing a sub-miniaturized loop antenna that offers improved performance, reduced size, and enhanced reliability. Its ability to operate across a wide frequency range with minimal complexity makes it an essential component for next-generation communication platforms.

OBJECT OF THE INVENTION
The primary object of the present invention is to develop a sub-miniaturized loop antenna that facilitates tactical communication across a wide frequency range, from Very Low Frequency (VLF) to S-BAND, while achieving significant miniaturization and enhanced performance.
Specific objectives of the invention include:

1. Miniaturization: To design an antenna with dimensions significantly smaller than traditional loop antennas, specifically less than 0.000005×λ at 10 kHz, enabling deployment in compact and mobile communication systems.
2. Wideband Operation: To achieve multi-octave impedance matching, allowing the antenna to operate efficiently across frequency bands including VLF, HF, VHF, UHF, L-Band, and S-BAND, without the need for complex matching circuits.
3. Improved Gain: To enhance the antenna's gain characteristics, achieving up to 30 dB improvement over the specified frequency range, thereby enabling long-range and reliable communication.
4. Structural Rigidity: To utilize industrial or MIL-grade printed circuit boards (PCBs) for the multi-turn loop circuit, ensuring structural rigidity and preventing issues such as intermittent connection and misalignment.
5. Simplified Connectivity: To incorporate a single RF cable assembly with a coaxial connector, eliminating multiple interconnections between the antenna and the front-end module, thus simplifying the system design.
6. Stable Communication: To establish a communication system that can reliably receive electromagnetic signals without distortion, suitable for use in ground terminals, submarines, and other tactical environments.

By achieving these objectives, the invention provides a robust and efficient solution for modern tactical communication systems, addressing the growing need for compact, reliable, and wideband antennas.

SUMMARY OF THE INVENTION
The following disclosure presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

The present invention relates to a sub-miniaturized loop antenna designed for tactical communication applications, offering significant advancements in miniaturization, wideband operation and performance. The invention leverages a high permeability cylindrical ring type ferrite core to enhance the magnetic field within the loop, thereby increasing radiation resistance and enabling efficient operation across a broad frequency range from Very Low Frequency (VLF) to S-BAND.

Aspects of the Invention

1. Miniaturization: The antenna is designed with dimensions less than 0.000005×λ at 10 kHz, making it significantly smaller than traditional loop antennas. This miniaturization is achieved through the use of a high permeability ferrite core and a multi-turn loop circuit printed on a flexible dielectric substrate.
2. Wideband Impedance Matching: The antenna achieves multi-octave impedance matching, allowing it to operate efficiently across frequency bands including VLF, HF, VHF, UHF, L-Band, and S-BAND. This is accomplished without the need for complex matching circuits, simplifying the design and integration process.
3. Improved Gain and Performance: The antenna is configured to achieve a gain improvement of up to 30 dB over the specified frequency range, enabling long-range and reliable communication. The design ensures stable signal reception and transmission, even in challenging environments.
4. Structural Rigidity and Reliability: The multi-turn loop circuit is realized using industrial or MIL-grade printed circuit boards (PCBs), ensuring structural rigidity and preventing issues such as intermittent connection, misalignment, and improper spacing.
5. Simplified Connectivity: The invention incorporates a single RF cable assembly with a coaxial connector, eliminating multiple interconnections between the antenna and the front-end module. This design choice enhances reliability and reduces system complexity.
6. Versatile Applications: The antenna is suitable for a wide range of tactical communication systems, including ground-based terminals, submarines, and mobile communication devices. Its compact form factor and wideband capabilities make it ideal for modern tactical operations.

Implementations of the Invention

• Antenna Design: The core design involves a cylindrical ring ferrite core with high permeability, combined with a multi-turn loop circuit printed on a flexible dielectric substrate. This configuration enhances the magnetic field and radiation resistance.
• Manufacturing Process: The use of industrial-grade PCBs and silver-coated foils ensures reliable electrical connectivity and structural integrity, facilitating easy manufacturing and deployment.
• System Integration: The antenna can be seamlessly integrated into existing communication systems, providing enhanced performance without requiring significant modifications to the system architecture.

By addressing the limitations of traditional loop antennas and offering a robust solution for tactical communication, the present invention represents a significant advancement in antenna technology, meeting the growing demand for compact, efficient, and wideband communication solutions.

Thus in accordance with an aspect of the present invention there is provided a sub-miniaturized loop antenna for tactical communication, comprising:
a cylindrical ring ferrite core having high permeability, configured to enhance the magnetic field within the loop;
a multi-turn loop circuit printed on a flexible dielectric substrate, wherein the loop circuit is electrically conductive and connected with silver-coated foils to facilitate connectivity;
an RF cable assembly with a coaxial connector, wherein the RF cable inner connector is connected to the electrical conductor of the loop circuit through the conductive foil, and the ground is connected to the other end of the loop circuit;
wherein the antenna is configured to operate over a frequency range from 10 kHz to 3 GHz, achieving multi-octave impedance matching and enabling tactical communication across VLF, HF, VHF, UHF, L-Band, and S-BAND frequency bands, and
wherein the antenna dimensions are less than 0.000005×λ at 10 kHz, achieving miniaturization and improved gain over the specified frequency range.

In accordance with another aspect of the present invention there is provided a communication system for tactical operations, comprising:
i) a sub-miniaturized loop antenna, including:
a cylindrical ring ferrite core having high permeability, configured to enhance the magnetic field within the loop;

a multi-turn loop circuit printed on a flexible dielectric substrate, wherein the loop circuit is electrically conductive and connected with silver-coated foils to facilitate connectivity;

an RF cable assembly with a coaxial connector, wherein the RF cable inner connector is connected to the electrical conductor of the loop circuit through the conductive foil, and the ground is connected to the other end of the loop circuit;

ii) a front-end module configured to interface with the sub-miniaturized loop antenna via a SMA-Male connector, facilitating signal transmission and reception;

wherein the communication system is configured to operate over a frequency range from 10 kHz to 3 GHz, achieving multi-octave impedance matching and enabling tactical communication across VLF, HF, VHF, UHF, L-Band, and S-BAND frequency bands, and wherein the system dimensions are less than 0.000005×λ at 10 kHz, achieving miniaturization and improved gain over the specified frequency range.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The accompanying figures illustrate various components of the sub-miniaturized loop antenna design of the present invention. These figures are provided to enhance the understanding of the invention and are not intended to limit its scope.

FIG. 1 Illustrates the cylindrical ring ferrite core and the multi-turn loop circuit. The ferrite core is shown in its cylindrical ring shape, which enhances the magnetic field within the loop, while the multi-turn loop circuit is depicted as printed on a flexible dielectric substrate, conforming to the core's structure.

FIG. 2 depicts the sub-miniaturized loop antenna system, including its key components: the cylindrical ring ferrite core, multi-turn loop circuit, and RF cable assembly. The figure highlights the integration of these components, showcasing the antenna's compact design and connectivity features.

FIG. 3 shows the experimental setup for performance evaluation using a Vector Network Analyzer (VNA). The setup includes a transmitter (Tx), receiver (Rx), and the distance (d) between them, demonstrating the antenna's ability to transmit and receive signals effectively across the specified frequency range.

FIG. 4 displays the Voltage Standing Wave Ratio (VSWR) measurement results obtained from the Vector Network Analyzer. The graph illustrates the antenna's impedance matching performance across the frequency range from 10 kHz to 3 GHz, highlighting its wideband capabilities and stable operation.

These figures collectively provide a comprehensive visual representation of the invention, its components, and its performance characteristics, supporting the detailed description and claims of the patent application.

Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may not have been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure.

DETAILED DESCRITION OF THE INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding, but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments belong. Further, the meaning of terms or words used in the specification and the claims should not be limited to the literal or commonly employed sense but should be construed in accordance with the spirit of the disclosure to most properly describe the present disclosure.
The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof.
The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown.

DETAILED DESCRIPTION OF THE INVENTION
The present invention is a sub-miniaturized loop antenna designed for tactical communication applications, offering significant advancements in miniaturization, wideband operation, and performance. The invention leverages a high permeability cylindrical ring type ferrite core to enhance the magnetic field within the loop, thereby increasing radiation resistance and enabling efficient operation across a broad frequency range from Very Low Frequency (VLF) to S-Band.

Embodiments of the Invention

1. Cylindrical Ring Ferrite Core:
The cylindrical ring ferrite core is a pivotal component of the sub-miniaturized loop antenna, designed to enhance the antenna's performance by amplifying the magnetic field within the loop. This core is composed of Mn-Zn soft ferrites, which are known for their exceptional magnetic properties, including high permeability and saturation levels. The choice of Mn-Zn ferrites is strategic, as these materials offer a permeability greater than 1000μ, which is essential for achieving the desired electromagnetic characteristics.

Material Composition and Properties
Mn-Zn ferrites are a type of soft ferrite, characterized by their ability to conduct magnetic flux with minimal energy loss. The high permeability of these ferrites allows them to effectively concentrate and channel the magnetic field within the loop, thereby increasing the radiation resistance of the antenna. This property is crucial for improving the efficiency of the antenna, as it enables better signal transmission and reception across a wide frequency range.

Cylindrical Shape and Design
The core is designed in a cylindrical ring shape, which offers several advantages:

1. Compactness: The cylindrical form factor contributes to the miniaturization of the antenna, allowing it to fit within space-constrained environments typical of tactical communication systems. This compact design is particularly beneficial for applications where size and weight are critical considerations.
2. Uniform Magnetic Field Distribution: The cylindrical shape ensures a uniform distribution of the magnetic field around the loop, enhancing the antenna's performance by providing consistent radiation resistance and impedance matching across the frequency spectrum.
3. Structural Integrity: The ring structure provides mechanical stability and robustness, ensuring that the core maintains its shape and properties under various environmental conditions. This is important for maintaining reliable performance in field applications.

Functional Role in the Antenna System

The cylindrical ring ferrite core plays a crucial role in the overall functionality of the antenna system:
• Magnetic Field Amplification: By amplifying the magnetic field within the loop, the core increases the radiation resistance, which is a measure of the antenna's ability to radiate electromagnetic energy effectively. This enhancement leads to improved signal strength and communication range.
• Impedance Matching: The high permeability of the ferrite core aids in achieving impedance matching over a wide frequency range, from VLF to S-BAND. This eliminates the need for complex matching circuits, simplifying the antenna design and integration process.
• Miniaturization: The core's compact design allows the antenna to achieve dimensions less than 0.000005×λ at 10 kHz, making it significantly smaller than traditional loop antennas. This miniaturization is a key advantage for deploying the antenna in mobile and portable communication systems.
In summary, the cylindrical ring ferrite core is a critical component that enhances the performance and efficiency of the sub-miniaturized loop antenna. Its high permeability and compact design contribute to the antenna's ability to operate effectively across a broad frequency range, making it an ideal solution for modern tactical communication applications.

2. Multi-Turn Loop Circuit:

The multi-turn loop circuit is a fundamental component of the sub-miniaturized loop antenna, designed to facilitate efficient electromagnetic signal transmission and reception. This circuit is printed on a flexible dielectric substrate, which serves as the foundation for the multi-turn configuration, offering several advantages in terms of design, functionality, and reliability.

Flexible Dielectric Substrate

The use of a flexible dielectric substrate is a key innovation in the design of the multi-turn loop circuit. This substrate provides a stable and adaptable platform for the circuit, allowing it to conform to the cylindrical shape of the ferrite core. The flexibility of the substrate is crucial for several reasons:

1. Conformability: The substrate can easily wrap around the cylindrical ferrite core, ensuring a snug fit and optimal alignment of the loop turns. This conformability is essential for maintaining consistent electromagnetic properties and performance.
2. Durability: The dielectric material is chosen for its robustness and ability to withstand environmental stresses, such as temperature fluctuations and mechanical vibrations, which are common in tactical communication environments.
3. Electrical Insulation: The substrate provides excellent electrical insulation, preventing short circuits and ensuring that the loop circuit operates efficiently without interference from external factors.

Multi-Turn Configuration
The multi-turn configuration of the loop circuit is designed to enhance the antenna's performance by increasing the effective length of the conductor within a compact space. This configuration offers several benefits:

1. Increased Inductance: By incorporating multiple turns, the loop circuit increases the inductance, which is beneficial for improving the antenna's radiation resistance and impedance matching capabilities.
2. Compact Design: The multi-turn approach allows for a more compact design compared to traditional single-turn loops, making it ideal for applications where space is limited.
3. Enhanced Signal Reception: The increased number of turns amplifies the induced current when exposed to an alternating magnetic field, thereby improving the antenna's ability to receive weak signals.

Electrical Conductivity and Connectivity
The loop circuit is electrically conductive, ensuring efficient signal transmission and reception. The use of silver-coated foils to connect the edges of the electrical conductor provides robust connectivity and structural integrity:

1. High Conductivity: Silver is chosen for its excellent electrical conductivity, which minimizes resistive losses and enhances the overall efficiency of the antenna.
2. Reliable Connections: The silver-coated foils ensure secure and reliable connections between the loop turns and the RF cable assembly, reducing the risk of intermittent connections and signal degradation.
3. Structural Integrity: The foils contribute to the mechanical stability of the loop circuit, ensuring that it maintains its shape and alignment during operation and handling.

Elimination of Traditional Coil Wrapping
The design of the multi-turn loop circuit eliminates the need for traditional coil wrapping, which involves manually winding wire around the ferrite core. This innovation reduces complexity and enhances reliability by:

1. Simplifying Manufacturing: The printed circuit approach streamlines the manufacturing process, reducing the time and labour required to produce the antenna.
2. Improving Consistency: The precision of printed circuits ensures consistent performance across multiple units, reducing variability and enhancing quality control.
3. Enhancing Durability: The elimination of coil wrapping reduces the risk of mechanical failure due to wire movement or misalignment, improving the long-term reliability of the antenna.

In summary, the multi-turn loop circuit is a critical component that enhances the performance, reliability, and manufacturability of the sub-miniaturized loop antenna. Its innovative design and use of advanced materials contribute to the antenna's ability to operate effectively across a wide frequency range, making it an ideal solution for modern tactical communication applications.

3. RF Cable Assembly:
The RF cable assembly is a vital component of the sub-miniaturized loop antenna, designed to facilitate efficient signal transmission and reception by providing a reliable connection between the antenna and external communication systems. This assembly incorporates a coaxial connector and is engineered to ensure robust electrical performance and ease of integration.

Functional Role in the Antenna System
The RF cable assembly plays a crucial role in the overall functionality of the antenna system:
• Signal Transmission and Reception: By providing a reliable connection between the loop circuit and the front-end module, the RF cable assembly ensures efficient transmission and reception of RF signals, enabling the antenna to perform its communication functions effectively.
• Impedance Matching: The coaxial design of the cable assembly helps maintain the characteristic impedance of the system, minimizing signal reflections and losses, which is critical for achieving optimal performance across the antenna's wide frequency range.
• Simplified Connectivity: The use of a single RF cable assembly with an SMA-Male connector eliminates the need for multiple interconnections, reducing potential points of failure and simplifying the overall system design.

In summary, the RF cable assembly is a key component that enhances the performance, reliability, and ease of integration of the sub-miniaturized loop antenna. Its design and functionality contribute to the antenna's ability to operate effectively in modern tactical communication applications, providing a robust solution for signal transmission and reception.

Constructional and Functional Interrelations
• The high permeability ferrite core and the multi-turn loop circuit work in tandem to enhance the magnetic field and radiation resistance, enabling efficient operation across a wide frequency range.
• The flexible dielectric substrate provides a stable platform for the loop circuit, ensuring proper electrical conductivity and structural rigidity.
• The RF cable assembly simplifies connectivity by eliminating multiple interconnections, reducing potential points of failure and enhancing system reliability.

DETAILED DESCRIPTION OF THE FIGURES
FIG. 1
This figure illustrates the structural components of the sub-miniaturized loop antenna, focusing on the cylindrical ring ferrite core (1) and the multi-turn loop circuit (2). The ferrite core (1) is depicted in its cylindrical ring shape, which is critical for enhancing the magnetic field within the loop and achieving miniaturization. The multi-turn loop circuit (2) is shown as being printed on a flexible dielectric substrate, which conforms to the cylindrical shape of the ferrite core (1). This configuration ensures optimal alignment of the loop turns and enhances the antenna's electromagnetic performance. The figure emphasizes the compact and integrated design of these components, which work together to achieve the desired miniaturization and wideband operation.

FIG. 2
This figure provides a detailed view of the sub-miniaturized loop antenna system, highlighting its key components: the cylindrical ring ferrite core (1), the multi-turn loop circuit (2), and the RF cable assembly (3). The RF cable assembly (3) is shown connected to the loop circuit (2), with the inner conductor of the coaxial cable interfacing with the electrical conductor of the loop circuit, and the ground connected to the opposite end. The figure demonstrates how these components are integrated to form a compact and efficient antenna system. The use of a single RF cable assembly (3) with a coaxial connector simplifies connectivity and enhances reliability, making the antenna suitable for tactical communication applications.

FIG. 3
This figure illustrates the experimental setup used to evaluate the performance of the sub-miniaturized loop antenna. The setup includes a Vector Network Analyzer (VNA), labeled as VNA, which is used to measure the antenna's performance parameters such as Voltage Standing Wave Ratio (VSWR) and gain. The transmitter (Tx) and receiver (Rx) are positioned at a distance (d) from each other, with the sub-miniaturized loop antenna integrated into the system. The figure demonstrates the antenna's ability to transmit and receive signals effectively across the specified frequency range, showcasing its suitability for tactical communication applications. The setup highlights the practical implementation of the antenna in a controlled testing environment.

In the figure, two identical LOOP antennas are considered as Transmitter and Receiver respectively. The Tx are Rx are connected to port1 and port 2 of Vector Network Analyzer (VNA). Set the power to 0dBm. This measurement setup is calibrated using Electronic-CAL prior to measurement and the Noise floor of VNA is maintained at minimum level of -100dBm to avoid output signal in noise level.
For LOOP antenna gain measurement, the below equations are used:
Received power (dBm) = transmitted power (dBm) + gain (dB) − losses (dB) … eq1
(Gain= Transmitter & Receiver)

Gain (Tx / Rx) = (Received power+ losses- Transmitted power)/2 …eq2
(Losses = Free space path and cable loss)

FIG. 4
This figure presents the Voltage Standing Wave Ratio (VSWR) measurement results obtained from the Vector Network Analyzer (VNA). The graph illustrates the antenna's impedance matching performance across the frequency range from 10 kHz to 3 GHz. The VSWR values are shown to remain below 3.5 across the entire frequency range, indicating excellent impedance matching and minimal signal reflection. This performance underscores the antenna's wideband capabilities and its ability to operate efficiently without the need for complex matching circuits. The figure provides a visual representation of the antenna's stable and reliable operation, making it ideal for modern tactical communication systems.

Best Mode of Working the Invention

The best mode of working the invention involves the following steps:
1. Assembly: The cylindrical ring ferrite core is positioned within the loop circuit printed on the flexible dielectric substrate. The silver-coated foils are used to connect the edges of the electrical conductor, ensuring robust connectivity.
2. Integration: The RF cable assembly is connected to the loop circuit, with the inner connector linked to the electrical conductor and the ground connected to the opposite end. The SMA-Male connector is used to interface with the front-end module.
3. Operation: The antenna is configured to operate over a frequency range from 10 kHz to 3 GHz, achieving multi-octave impedance matching and enabling tactical communication across VLF, HF, VHF, UHF, L-Band, and S-BAND frequency bands. The design ensures stable and reliable communication without distortion, even in challenging environments.
4. Performance Evaluation: The antenna's performance is evaluated using a vector Network Analyzer, as depicted in FIG. 2, to measure parameters such as VSWR and gain across the specified frequency range.

By addressing the limitations of traditional loop antennas and offering a robust solution for tactical communication, the present invention represents a significant advancement in antenna technology, meeting the growing demand for compact, efficient, and wideband communication solutions.

These figures collectively provide a detailed visual representation of the invention, its components, and its performance characteristics, supporting the detailed description and claims of the patent application.

ADVANTAGES OF THE PRESENT INVENTION

1. Miniaturization: The antenna's compact design, with dimensions less than 0.000005×λ at 10 kHz, allows for deployment in space-constrained environments, making it ideal for mobile and portable tactical communication systems.
2. Wideband Operation: The antenna operates efficiently across a broad frequency range from 10 kHz to 3 GHz, covering VLF, HF, VHF, UHF, L-Band, and S-BAND, without the need for complex matching circuits. This wideband capability ensures versatility and adaptability in various communication scenarios.
3. Improved Gain: The design achieves a gain improvement of up to 30 dB, enhancing signal strength and enabling long-range communication, which is critical for tactical operations.
4. Enhanced Reliability: The use of industrial or MIL-grade printed circuit boards (PCBs) and silver-coated foils ensures structural rigidity and robust connectivity, reducing the risk of intermittent connections and mechanical failures.
5. Simplified Integration: The RF cable assembly with an SMA-Male connector facilitates seamless integration with front-end modules, eliminating multiple interconnections and simplifying the overall system design.
6. Stable Communication: The antenna provides stable and reliable communication without distortion, even in challenging environments, ensuring consistent performance in tactical applications.
7. Cost-Effective Manufacturing: The elimination of traditional coil wrapping and the use of printed circuit technology streamline the manufacturing process, reducing production costs and time.

These advantages collectively make the invention a robust and efficient solution for modern tactical communication needs, addressing the growing demand for compact, reliable, and wideband antennas.

The descriptions and illustrations provided in this document are intended to explain the principles of the invention and its best mode of working. They are not intended to limit the scope of the invention, which is defined by the claims. Variations and modifications to the described embodiments may be made without departing from the scope of the invention. The specific embodiments described in this document are examples of the invention and are not intended to limit the scope of the claims. The claims should be interpreted broadly to cover all equivalent structures and methods that fall within the scope of the invention. The technical specifications and details provided in this document are for illustrative purposes only. Actual implementations of the invention may vary based on specific design requirements, manufacturing processes, and application needs.

Any references to prior art documents, patents, or publications are provided for informational purposes only. The inclusion of such references does not imply that the present invention is limited by or dependent on the prior art.
, Claims:
1. A sub-miniaturized loop antenna for tactical communication, comprising:
a cylindrical ring ferrite core (1) having high permeability, configured to enhance the magnetic field within the loop;
a multi-turn loop circuit (2) printed on a flexible dielectric substrate, wherein the loop circuit is electrically conductive and connected with silver-coated foils to facilitate connectivity;
an RF cable assembly (3) with a coaxial connector, wherein the RF cable inner connector is connected to the electrical conductor of the loop circuit (2) through the conductive foil, and the ground is connected to the other end of the loop circuit (2);
wherein the antenna is configured to operate over a frequency range from 10 kHz to 3 GHz, achieving multi-octave impedance matching and enabling tactical communication across VLF, HF, VHF, UHF, L-Band, and S-BAND frequency bands; and
wherein the antenna dimensions are less than 0.000005×λ at 10 kHz, achieving miniaturization and improved gain over the specified frequency range.

2. The sub-miniaturized loop antenna of claim 1, wherein the ferrite core (1) is composed of Mn-Zn soft ferrites with a permeability greater than 1000μ.

3. The sub-miniaturized loop antenna of claim 1, wherein the multi-turn loop circuit (2) is adapted to eliminate the need for wrapping coil wire upon the ferrite core (1).

4. The sub-miniaturized loop antenna of claim 1, wherein the RF cable assembly (3) further comprises an SMA-Male connector for connection to a front-end module.

5. The sub-miniaturized loop antenna of claim 1, wherein the cylindrical ring ferrite core (1) is configured to achieve a Voltage Standing Wave Ratio (VSWR) of less than 3.5 across the operating frequency range.

6. The sub-miniaturized loop antenna of claim 1, wherein the multi-turn loop circuit (2) is realized using an industrial or MIL-grade printed circuit board (PCB) to ensure structural rigidity and prevent issues such as intermittent connection, misalignment of the loop strip, and improper spacing in the multi-turn loop.

7. The sub-miniaturized loop antenna of claim 1, further comprising a copper pad at the end of the RF cable assembly (3) to ensure proper excitation and grounding, thereby improving structural rigidity for industrial applications.

8. The sub-miniaturized loop antenna of claim 1, wherein the antenna is configured to achieve a gain improvement of up to 30 dB over the specified frequency range, enabling enhanced tactical communication.

9. The sub-miniaturized loop antenna of claim 1, wherein the antenna is configured to operate without a matching circuit at low frequencies, utilizing the combination of multiple turns in the loop circuit (2) and high permeability material in the ferrite core (1) for impedance matching.

10. A communication system for tactical operations, comprising:
i) a sub-miniaturized loop antenna, including:
 a cylindrical ring ferrite core (1) having high permeability, configured to enhance the magnetic field within the loop;
 a multi-turn loop circuit (2) printed on a flexible dielectric substrate, wherein the loop circuit is electrically conductive and connected with silver-coated foils to facilitate connectivity;
 an RF cable assembly (3) with a coaxial connector, wherein the RF cable inner connector is connected to the electrical conductor of the loop circuit (2) through the conductive foil, and the ground is connected to the other end of the loop circuit (2);
ii) a front-end module configured to interface with the sub-miniaturized loop antenna via an SMA-Male connector, facilitating signal transmission and reception;
wherein the communication system is configured to operate over a frequency range from 10 kHz to 3 GHz, achieving multi-octave impedance matching and enabling tactical communication across VLF, HF, VHF, UHF, L-Band, and S-BAND frequency bands; and
wherein the system dimensions are less than 0.000005×λ at 10 kHz, achieving miniaturization and improved gain over the specified frequency range.

11. The communication system of claim 10, wherein the ferrite core (1) is composed of Mn-Zn soft ferrites with a permeability greater than 1000μ.

12. The communication system of claim 10, wherein the multi-turn loop circuit (2) is adapted to eliminate the need for wrapping coil wire upon the ferrite core (1).

13. The communication system of claim 10, wherein the cylindrical ring ferrite core (1) of the sub-miniaturized loop antenna is configured to achieve a Voltage Standing Wave Ratio (VSWR) of less than 3.5 across the operating frequency range.

14. The communication system of claim 10, wherein the multi-turn loop circuit (2) of the sub-miniaturized loop antenna is realized using an industrial or MIL-grade printed circuit board (PCB) to ensure structural rigidity and prevent issues such as intermittent connection, misalignment of the loop strip, and improper spacing in the multi-turn loop.

15. The communication system of claim 10, further comprising a copper pad at the end of the RF cable assembly (3) of the sub-miniaturized loop antenna to ensure proper excitation and grounding, thereby improving structural rigidity for industrial applications.

16. The communication system of claim 10, wherein the system is configured to achieve a gain improvement of up to 30 dB over the specified frequency range, enabling enhanced tactical communication.

17. The communication system of claim 10, wherein the system is configured to operate without a matching circuit at low frequencies, utilizing the combination of multiple turns in the loop circuit (2) and high permeability material in the ferrite core (1) for impedance matching.