Surface Wave Antenna Loop Design for Space Wave Suppression
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Solution Overview
Problem
Current large radiating pylons for transmitting high-power signals are expensive, require extensive safety grounds, are unsightly, and are not optimized for surface wave propagation, generating significant space waves that can interfere with ionospheric signals and have a limited passband.
Innovation Solution
A surface wave antenna design featuring a metal excitation loop positioned at least 1 m above a conductive medium with a length of λ/2, comprising two parallel portions separated by no more than λ/50, which reduces space wave radiation by using currents of opposite directions, thereby enhancing ionospheric protection and increasing the passband while minimizing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If radiating pylons or whip/biconical antennas are used for high-power transmission, then transmission power is achieved, but space wave radiation is generated causing ionospheric interference and fading phenomena
Solution Approach 1:
The antenna is divided into two distinct parts: a horizontal ground plane section for efficient power transmission and a vertical whip section for controlled radiation. This segmentation allows the horizontal component to conduct high currents with minimal radiation, while the vertical component provides the necessary radiation function with reduced space wave generation
Solution Approach 2:
Instead of using conventional vertical pylons that radiate omnidirectionally including harmful space waves, the invention inverts the approach by using a horizontal ground plane as the primary element and adding a minimal vertical component. This inverted configuration fundamentally changes the radiation pattern to suppress space waves while maintaining transmission power
2Ease of operation
If conventional antennas are used, then transmission function is provided, but the structure is expensive and requires extensive safety grounds
Solution Approach 1:
The horizontal ground plane serves multiple functions simultaneously: it acts as the primary radiating element, provides the necessary ground reference, reduces the need for additional safety grounds, and suppresses unwanted space wave radiation. This multi-functionality eliminates several separate components required by conventional antenna systems
3Reliability
If ground antennas are used to promote surface wave propagation, then surface wave radiation is enhanced, but the antenna has large surface bulk and narrow passband
Solution Approach 1:
The antenna incorporates adjustable loading elements (such as variable capacitors or inductors) that allow dynamic tuning of the resonant frequency and passband width. This dynamic adjustment capability enables the antenna to maintain efficient surface wave propagation across a broader frequency range while keeping the physical structure compact
4Object-generated harmful factors
If ground antennas are used to minimize space wave radiation, then ionospheric protection is improved, but the passband is narrowed
Solution Approach 1:
The antenna design incorporates variable electrical parameters through adjustable loading elements that can be tuned to change the resonant frequency and impedance characteristics. This allows the passband width and center frequency to be adjusted independently while maintaining the suppressed space wave radiation characteristic through the fundamental horizontal ground plane configuration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The antenna significantly reduces space wave radiation, improves ionospheric protection over short and medium distances, and enlarges the passband while maintaining discretion and resistance to environmental factors like wind and lightning.
Implementation Method 1
The discontinuity between the air and the ground, located on and in the ground at the periphery of the antenna, between the pair ground and metal ground plane, on the one hand, and the ground without the metal ground plane, on the other hand, favors the propagation of an omnidirectional ground wave in vertical polarization.
Implementation Method 2
The ground wave is due to the injection of high currents in the ground, a consequence of a low ohmic resistance of the antenna
Implementation Method 3
the excitation loop comprises two approximately parallel portions separated by at most approximately λ/50 and able to extend approximately parallel to the surface of the conductive medium in a plane approximately perpendicular to said surface and to be traversed by currents of opposite directions
Data Source
Figure 1~4
Figure 5~8
Figure 9~12
AI summary
The antenna comprises a metal excitation loop (B1) to be positioned at a height (h) of at least about 1 m above the surface (SM) of a conducting medium (M) and a supply means (A, L1n) to be connected to the conducting medium. The perimeter of the loop is about one half of the operating wavelength, namely ?/2, in length. The loop comprises two approximately parallel portions (I1p-I1n, S1) which are at most about ?/50 apart and are capable of extending approximately parallel to said surface in a plane approximately perpendicular to said surface, currents of opposite direction flowing through said portions. The closest portion to said surface includes an aperture between ends (E1p, E1n) of the loop that are connected to the supply means. The antenna is better protected from space waves and it can be reduced in size by being folded up.