Category - Models

“Models” is a category showcasing posts featuring antenna designs created using AN-SOF. The category covers the design process, simulation results, and antenna performance analysis.

Cylindrical Antenna

A center-fed cylindrical antenna is the simplest example that we can simulate. It consists of a straight wire with a source at its center and becomes a half-wave dipole when the frequency is such that the length of the antenna is half the wavelength.
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Monopole Over Real Ground

A monopole is a vertical element connected to a ground plane and with the feed point at its base. In this example we will simulate a radio mast on an imperfect ground, which is used for broadcasting in the LF and MF bands.
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Helix Antenna in Axial Mode

The helix is a good example where we need curved segments to describe the geometry of the antenna. When the length of the helix is of the order of or greater than the wavelength, it can work in the so-called "axial mode".
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Loop Antenna

A good example where we need curved segments to model an antenna is the circular loop case. When the loop is small compared to the wavelength, the radiation resistance is proportional to the square of the loop area.
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A Transmission Line

Two-wire transmission lines can be modeled explicitly in AN-SOF. In this example, the line will have a single wire but there will be a ground plane below it, so we have the mirror image of the wire as the return of the line.
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An RLC Circuit

The ability of AN-SOF to simulate at extremely low frequencies can be demonstrated with a model of an RLC circuit that will resonate at only 800 Hz, so the wavelength is 375 km!
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Modeling an ISM 433MHz Helical Antenna with AN-SOF.

ISM 433MHz Helical Antenna

Small helical antennas for the 433 MHz ISM band are a good example where we need advanced software that has the ability to model curved wires with exact description of the helix contour.
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Modeling Radio Masts in AN-SOF.

Radio Mast Above Wire Screen

Radiating towers or radio masts can be modeled in AN-SOF with a high degree of detail. This example shows a quarter-wave monopole antenna connected to a radial wire ground screen on a real ground plane.
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Receiving Loop Antenna

Frequency sweep simulation of a receiving circular loop antenna. The loop is modeled using conformal segments, which exactly follow the contour of the antenna geometry.
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Monopole Above Earth Ground

The monopole is used for AM (Amplitude Modulation) radio transmissions. The far-field radiation pattern in the Fraunhofer zone is distorted due to the finite conductivity of the soil.
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Top-Loaded Short Monopole

The antenna is composed of four vertical monopoles over ground. Each monopole is fed at its base by a voltage source of the same amplitude and phase as the others.
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Half-Wave Dipole

Center-fed half-wave dipole antenna at 300 MHz. The wavelength is close to 1 meter, so the dipole length equals 0.5 meters. 
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Folded Dipole

Simulation of a folded dipole using curved wires at the dipole ends. The curved part is modeled exactly using conformal segments.
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Dipole Antenna

Frequency sweep simulation of a cylindrical dipole antenna. The results show how the current distribution along the wire approaches a sine function.
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Modeling an 80 m Spiral Loop with AN-SOF.

An 80 meters DX Antenna: A Spiral Loop

A half-wave dipole would have a length of 40 meters in this band (3.75 MHz), difficult to install at home due to lack of space. Not to mention the complaints from our neighbors. A spiral loop is attractive for its small size and relative ease of tuning because it is basically an inductor.
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Directional V Antenna

The horizontal arms of the V-antenna are 3 wavelengths long, so six semi-cycles of a sine function can be seen as a current distribution along the arms.
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5-Element Yagi-Uda antenna with folded dipole

5-Element Yagi-Uda

Simulation of a Yagi antenna that consists of five linear wires. The driven element is a folded dipole which does not change the radiation pattern shape, but it changes the input impedance for an easier impedance matching.
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Modeling an Array of Snowflake Quads with AN-SOF.

Array of Snowflake Quads

Nathan Cohen in the US fractalized the quad loop based on the Minkowski square and invented an array of two elements. The biggest advantage of fractal antennas is that we get a wide bandwidth with a small size. This simulation shows that we can almost double the bandwidth with a 3-element array.
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Dish Antenna

The reflector is modeled by a grid of curved segments. The hole sizes are small compared to the wavelength near the center of the parabola, buy they approach half-wavelength away from the center.
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MI2 Fractal Loop

This MI2 Fractal Loop antenna was designed by Dr. Nathan Cohen. Results were reported in Cohen, N. L., and Hohlfeld, R. G., "Fractal Loops and the Small Loop Approximation", Communications Quarterly, 6, 77-81, (1996).
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Random Loop

This random loop antenna was designed by VE9SRB in an attempt to demonstrate that a MI2 Fractal Loop-like performance can be obtained with an arbitrarily shaped geometry.
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Modeling an Array of Snowflake Quads with AN-SOF.

Array of Snowflake Quads

Nathan Cohen in the US fractalized the quad loop based on the Minkowski square and invented an array of two elements. The biggest advantage of fractal antennas is that we get a wide bandwidth with a small size. This simulation shows that we can almost double the bandwidth with a 3-element array.
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Modeling a capacitively fed microstrip antenna with AN-SOF.

Capacitively-Fed Patch

Microstrip patch antennas with capacitive feeding have been key in the development of the cell phone industry. This way of feeding compact antennas, for instance PIFAs, has made it possible to cancel out the probe reactance and simplify the matching network.
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Modeling an 80 m Spiral Loop with AN-SOF.

80m DX Spiral Loop

A half-wave dipole would have a length of 40 meters in this band (3.75 MHz), difficult to install at home due to lack of space. A spiral loop is attractive for its small size and relative ease of tuning because it is basically an inductor to which a variable capacitor is connected at the feed point to achieve resonance.
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