Antennas - Science topic

1. Create a new scenario or edit an existing one.

2. Go to the "Devices" tab and select the gNB (base station) you want to modify.

3. In the "Antenna" section, select "Sector" as the antenna type.

4. Set the "Sector Angle" to the desired value (e.g., 120 degrees for a tri-sector gNB).

5. Set the "Orientation" to the desired value (e.g., 0, 120, or 240 degrees for a tri-sector gNB).

6. To simulate tri-sector gNBs, create three separate gNB devices, each with a sector antenna and a different orientation (0, 120, and 240 degrees).

7. To find the load in each sector, you can use the "Network Performance" metrics in NetSim, such as:

"UE Distribution" to see the number of UEs connected to each sector.

"Throughput" and "Traffic" metrics to see the load on each sector.

Negative gain in dB (or probably dBi) means that it radiates less in that direction than an imaginary reference omnidirectional or isotropic antenna would. -1 dB means about 80%, -3 dB means about 50%. An imaginary reference omnidirectional antenna radiates all the input power evenly in all directions. This is defined to have a gain of 1 in all directions, which is 0 dBi (i means isotropic).

If you have negative gain you may not have successfully designed a multi-band frequency-reconfigurable antenna. It depends on whether good gain was a requirement. Antennas are usually made reconfigurable so that they have useable gain at each frequency and/or direction chosen. Good gain means longer battery life and/or longer range and/or higher data rate.

Just use transform copy with the separation you need.

From the paper below it would seem that the cap only acts as a reflector of radiated power (not a resonator) so if you can estimate the reflection coefficient it may allow you to compensate for it. I'd expect that the reflections should be in the high 90% though which won't affect the result much.

You may have better articles available than the one below, but that looks like it might have enough to work with!

See https://www.researchgate.net/post/How_can_I_accurately_determine_the_count_of_handovers_taking_place_within_a_5G_network_when_simulating_with_NetSim/1, its been answered there.

There isn't a straightforward way to extract circuit parameter values directly from an IDC ZOR antenna. IDC ZOR antennas are physical structures designed to radiate or receive electromagnetic waves, and their properties are typically described in the antenna's scattering parameters (S-parameters) rather than circuit parameters.

S-parameters describe how a device performs under specific frequencies. They relate the incident wave to the reflected and transmitted waves at the antenna's ports.

If you have the S-parameter data for your IDC ZOR antenna, you might be able to use it to calculate some relevant circuit parameters using formulas, but this would likely require knowledge of antenna theory and specific design details of the IDC ZOR antenna.

Here are some resources that you might find helpful:

Vladimir Burtsev , решил проблему с помощью Вашего предложения с Bending. Ранее я задавал параметр изгиба как аналитическую кривую, которая создавалась через формулу А*t*t. Видимо, данный способ описания искривления не подходит. Спасибо.

Array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive, While MIMO antenna works as multiple set of individual antenna. MIMO uses multiple antennas to handle multiple signal paths simultaneously.

1. https://www.elprocus.com/antenna-array/

2. https://www.waveform.com/a/b/guides/mimo-antenna-guide

S11 is a coefficient that reflects the amount of energy reflected by a material or surface. For example, if you want to design a unit cell for a frequency selective surface (FSS), the goal should be to have maximum reflection (0dB) and minimum transmission (for example, -20 dB) at resonance frequencies. Similarly, if you want to design a metamaterial that passes maximum signal and has less reflection, then S11 should be minimized (i.e., -20 dB), and transmission should be maximized (S21 ~ 0 dB). The specific application of the unit cell determines the desired values for S11 and transmission.

AW-Band Metallic Via-Based Inline Microstrip-to-WR10 Transition for mm-Wave, Satellite and RADAR Applications

i hope this paper will help you in this regard

All the best

You can use field monitors to calculate and save the E and H fields from a run. Then you can use the post-processing to obtain them on the surface you want.

Here！

Bhagwati Sharan

The issue stems from the high number of meshes in your simulation. To rectify this, you can reduce the number of meshes by adjusting the mesh properties. Once you've made the necessary modifications, your simulation starts without any hindrance.

Good Luck Dear

Thank you very much Smrity Dwivedi

The unit of CCL (Channel Capacity Loss) in a MIMO antenna system is bits per Hertz per second (bps/Hz/s).

Here's a breakdown of the units:

CCL essentially quantifies how much information capacity is lost due to limitations in the MIMO antenna system. A lower CCL value indicates better performance.

I also face same problem, did you find any solution?

Yes, the diversity gain is dimensionless. In principle, one can compute 10*log10(DG) to obtain a dB-value

You may use the equivalent circuit mentioned in the datasheet for the ON and OFF case to represent the PIN diode.

The coupling between resonant circuits is a well known and well described.

Change of resonant frequencies due to coupling depends on type of coupling and coup[ling coefficient. The eigenfrequency formulas give the answer. The theory can be found in my paper "Analysis of Coupled Dielectric Resonators by Means of Eigenfrequency Method", European Microwave Conference, Cannes, 1994, which is available at ResearchGate, or many other papers.

MIMO antennas are not suitable for wireless communications systems and do not share the group plane. so, the antenna elements need to be connected to ground.

Rabin Kanisha thank you .

Yes, sir, but how to equivalent RLC resonant circuit, slits, and decoupling element? i mean any particular procedure to equivalent the circuit

Priyanchal Khare Make use planar monopole antenna design formulas for computing partial ground length.

This is an antenna. It will transmit and receive. Reflections from surrounding objects will be received and will add to S11 measurements. If the objects move, the reflection will change and S11 will change.

S11 of -45 dB is very low. If it drops to -65 dB then the extra reflected signal coming back nearly cancels it entirely so is very close to -45 dB, which is 0.003% of the transmitted signal. Signals at this level do change the resonant frequency, but not by any amount you can notice. It is similar to frequency pulling of oscillators.

Hello

I have encountered the same error!!

Have you found a way to solve this?

Xiangwen Wang

Frequency units are in MHz and dimensions are in cm

Smrity Dwivedi

Nikolay Pavlov

What you describe is the reactive near field. Even in this region there is some radiation, the radiated power has to travel through this region. The reactive fields fall off as inverse cube and inverse square, whereas the radiation fields fall off just as the inverse of distance so carry a constant power away at each distance. Because of the different rates of fall-off, the radiation fields can be very small compared to the reactive fields close to the antenna.

There are several regions. Three are:

The reactive near field, where the fields look mostly like those of a capacitor or inductor - or both.

The radiating near field, where the radiating fields start to dominate, but the shape of the radiation pattern is not the same as in the far field.

and the far field, where the radiation pattern is constant at all larger ranges.

For an antenna more than a few wavelengths across, the far-field can be considered as starting at the distance given by twice the antenna width times the number of wavelengths across that width. commonly referred to as 2D²/lambda. The reactive near-field boundary is about 1/6 wavelength from the antenna.

For a given number of antennas, there is a maximum diversity gain that one can achieve according to the underlying theory. I guess the authors of the paper compare their measurements with the theoretic limit.

Since they said 10 dB, I would guess that they considered an array with 10 antennas. If there were 20 antennas, the maximum would then instead be 13 dB.

There are some different ways to measure the diversity gain, so I cannot tell precisely what they had in mind in this work.

This website contains the general equation for the link budget

You can find a short description on Wikipedia: https://en.wikipedia.org/wiki/MIMO#Mathematical_description

If you want to learn the topic in detail, I recommend Chapter 3 in my book "Introduction to Multiple Antenna Communications and Reconfigurable Surfaces" which you can download here:

an "ME" antenna is a Huygens source, which consists of an electrically-short electric dipole and an orthogonal short magnetic dipole. The combination then radiates in one direction only, like a Huygens source, when the M and E dipoles are excited in-phase. The magneto-strictive part is your magnetic dipole. The piezzoelectric part is the electric dipole, so you need both to make a Huygens source. Each dipole on its own is merely a short dipole which radiates in all directions (except along its axis).

Hello, how did you solve the problem of adding complex impedance port feed in CST?

Hello,

In HFSS, first find the plane containing the E-field, e-g Y-Z plane contains the E-field, then go to results--> create far field report-->directivity or gain --> directivity phi or directivity theta and plot the result. this will give you the co and cross of the E-field.

Thanks,

0.8 m/sec is an average speed.

While both multiantenna systems and MIMO (Multiple-Input Multiple-Output) antennas involve using multiple antennas, they are distinct in terms of their functionality and complexity:

Here's an analogy to understand the difference:

Greetings, i hope channel capacity for MIMO antenna can never be blindly calculated without accounting the channel model to be delt with.

If you can measure the S11 over the bandwidth, and the plot on the smith chart is a circle touching the outside, then the loaded and unloaded Q can be measured from the bandwidths where the circle crosses some easily found curves and lines. Q = (centre frequency)/bandwidth

Set the reference plane so it is close to the antenna (the loop makes a circle, and the ends cross at the edge of the smith chart). Adjust the reference plane slightly until the circle touches the edge at 3 o'clock (1, j0).

The loaded Q (Q_L) is given by the frequency difference between the frequencies where the circle crosses the diagonal lines from 3 o'clock (1, j0) to 12 o'clock (0, j), and from 3 o'clock (1, j0) to 6 o'clock (0, -j).

The unloaded Q (Q₀) is given by the frequency difference between the frequencies where the circle crosses the two arcs from 3 o'clock (1, j0) to 9 o'clock (-1, j0) centred at 12 o'clock (0, j) and 6 o'clock (0, -j).

If the circle looks better rotated to another position on the chart, then just use the same lines rotated by the same amount from 3 o'clock.

A slow-wave structure, when integrated into an antenna, serves several important purposes:

1. Increase directivity and gain: By slowing down the electromagnetic waves within the antenna, the interaction between the waves and the radiating structure is enhanced. This leads to a more focused beam of radiation, resulting in higher directivity and gain. This is particularly beneficial for applications where long-range communication or precise targeting is required.

2. Miniaturization: Traditional antennas often require large physical dimensions to achieve desired operating frequencies. Integrating a slow-wave structure allows for the antenna to be physically smaller while maintaining the same operational frequency. This is crucial for applications where space is limited, such as in mobile devices or aircraft.

📷Opens in a new window📷www.researchgate.net

Slow wave structure antenna miniaturization

3. Enhance bandwidth: Slow-wave structures can broaden the operating bandwidth of an antenna, allowing it to function effectively over a wider range of frequencies. This is useful for applications like radars and communication systems that need to operate across multiple channels.

📷Opens in a new window📷www.researchgate.net

Slow wave structure antenna bandwidth

4. Improve impedance matching: By manipulating the electrical properties of the antenna, slow-wave structures can help to better match the antenna's impedance to the feedline. This improves the efficiency of power transfer and reduces signal reflections, leading to better overall performance.

📷Opens in a new window📷www.microwaves101.com

Slow wave structure antenna impedance matching

5. Specific applications: Slow-wave antennas find applications in various fields, including:

The specific design and implementation of a slow-wave structure in an antenna will depend on the desired operating frequency, bandwidth, directivity, and other performance parameters. However, the overall goal is to improve the antenna's efficiency and effectiveness in its intended application.

I understand your challenge in measuring the efficiency of your fabricated SWB antenna and comparing it with the simulation results. Several approaches are available, each with its own advantages and limitations. Choosing the most reliable and feasible method depends on factors like your specific setup, desired accuracy, and available resources.

Here's a breakdown of some common approaches for measuring SWB antenna efficiency:

Ultimately, the best approach depends on your specific needs and constraints. Consider consulting with antenna experts or using simulation tools to compare different methods and choose the one that best suits your requirements.

I hope this information helps you.

Hi, PLA is a terrible choice for this purpose. Can your printer work with some other material like ABS or PETG? PLA has a glass transition at around 60 °C, which means it will start to soften already at 50°C. These temperatures are easily reached on direct sun in hot climate. You must keep it cool. A reflective coating can help, but it will not solve the issue entirely.

Smrity Dwivedi ma'am i want to ask that what unit should be selected for ECC and CCL?

If the focus is on antenna design, then I recommend IEEE Transactions on Antennas and Propagation.

If you are working on MIMO algorithms, there are other journals from the Communications Society or Signal Processing Society that are a better fit.

Hi!

1. I wouldn't recommend using the exponential correlation model because it is not a physically motivated model, so it is unable to model the spatial correlation at a UPA. You can instead consider the model that we describe in the following paper: https://arxiv.org/pdf/2108.04633.pdf

It describes the spatial correlation between the antennas when there are scattering clusters in specific angular directions.

2. All physically motivated models are based on the steering vectors (called array response vectors in my paper). The starting point is Eq. (2) which is the integral over steering vectors multiplied by factors that determine how much signal energy comes from different directions.

You can use an infinite plane wave excitation from any direction you choose, which may be what you want. You can have far-field results.

If it has a ground plane and you are looking at propagation across the array then you can use a waveguide port full width along one of the edges, from the ground to several board thicknesses above the top of the board. You can choose which or how many modes to use.

it seems that this is how photons move at the speed of light, even at infinite distances, as the moving photons created during the big bang began to propagate through space as space also began to create itself and to expand at the speed of its vibrational waves which propagate at speed c. But according to me, space vibrates at a wavelength of 1.609344 km. And the photons move at speed c thanks to the spatial vibration according to (1.609344 km = ct). This is why they move at the speed of of the waves of the vibration of the space. The constants of the vibrating space are ε0 and μ0 as given in the known formula: cc=1/ε0μ0.

Several techniques can be employed to enhance the S11 (reflection coefficient) of a Vivaldi antenna to below -20 dB. These methods primarily focus on impedance matching and minimizing reflections at the feed point. Here are some effective approaches:

By implementing these techniques, one can effectively improve the S11 of a Vivaldi antenna to less than -20 dB, achieving better impedance matching and minimizing reflections.

In COMSOL:

10.1088/1361-6463/aceb6f

You can also use surface current to know exactly the active region for each frequency ,it's simple and practical

Hello,

In conventional form during cutting, you have to observe the surface current distribution, you can also incorporate the slots or slits accordingly on the surface of the patch or at corner/side edges. Ground plane defection or MGS, DMS are also options.

Thanks,

To calculate the Radar Cross Section (RCS) of a MIMO antenna in HFSS, you can follow these steps:

RCS = 10 * log10(|(S11 * S22) - (S12 * S21)|^2)

where:

Here is an example of how to calculate the RCS of a MIMO antenna in HFSS:

import numpy as np import math def calculate_rcs(s11, s22, s12, s21, theta, phi): """ Calculates the radar cross section (RCS) of a MIMO antenna. Args: s11 (complex): The S11 parameter of the antenna. s22 (complex): The S22 parameter of the antenna. s12 (complex): The S12 parameter of the antenna. s21 (complex): The S21 parameter of the antenna. theta (float): The elevation angle in radians. phi (float): The azimuth angle in radians. Returns: float: The RCS of the antenna in dBm^2. """ # Calculate the far-field pattern f1 = np.abs(s11) * np.exp(-1j * 2 * math.pi * np.sin(theta) * np.cos(phi)) f2 = np.abs(s22) * np.exp(-1j * 2 * math.pi * np.sin(theta) * np.sin(phi)) f3 = np.abs(s12) * np.exp(-1j * 2 * math.pi * np.cos(theta)) f4 = np.abs(s21) * np.exp(-1j * 2 * math.pi * np.cos(theta)) E = f1 + f2 + f3 + f4 # Calculate the RCS rcs = 20 * np.log10(np.abs(E) ** 2) return rcs # Example usage s11 = 0.5 + 0.5j s22 = 0.4 + 0.4j s12 = 0.3 + 0.3j s21 = 0.2 + 0.2j theta = math.pi / 4 phi = math.pi / 4 rcs = calculate_rcs(s11, s22, s12, s21, theta, phi) print(rcs)

This code will calculate the RCS of a MIMO antenna at a single frequency and angle. You can modify the code to calculate the RCS at multiple frequencies and angles.

Fritz Caspers

You may already know this!

rfid in this band uses a very weakly coupled resonant air-cored magnetic transformer. Read the application notes - they are interesting and fun. It isn't an antenna. It is in the inductive near field, where the coupling is 1/r³. The tag is the secondary and receives enough power to turn on, and modulate its own impedance, which is detected as a very small impedance change in the primary. The system doesn't radiate (much), so it is like a toothbrush charger, but much more weakly coupled. Power goes into the tag, and is wasted only to losses in the primary, and to eddy currents in any surrounding metalwork.

There are two main methods to fit a distribution to a set of data in MATLAB:

1. Using the fitdist function

The fitdist function is the most versatile and commonly used method for fitting distributions to data in MATLAB. It takes two required arguments:

For example, to fit a normal distribution to the data vector x, you would use the following command:

Code snippet

pd = fitdist(x, 'normal');

content_copyUse code with caution. Learn more

The fitdist function returns a probability distribution object pd that contains the estimated parameters of the fitted distribution. You can use the pd object to evaluate the probability density function (PDF), cumulative distribution function (CDF), quantile function, and other properties of the distribution.

The Distribution Fitter app is a graphical user interface (GUI) that provides a convenient way to fit distributions to data in MATLAB. To use the Distribution Fitter app, follow these steps:

The Distribution Fitter app will display a variety of plots and statistics that can be used to assess the goodness of fit of the distribution.

Both the fitdist function and the Distribution Fitter app provide a number of additional options that you can use to customize the fitting process. For example, you can specify the fitting method (e.g., maximum likelihood, least squares), set confidence intervals, and plot the fitted distribution along with the data.

The best method for fitting a distribution to data in MATLAB depends on your specific needs. If you need more control over the fitting process, then the fitdist function is a good choice. However, if you are looking for a more user-friendly interface, then the Distribution Fitter app is a better option.

Hello,

Few more papers are attached.

Thanks,

MIMO antenna parameters such as Envelope Correlation Coefficient (ECC) and Diversity Gain (DG) can be found from far-field radiation patterns by following these steps:

Here are the mathematical formulas for calculating ECC and DG from far-field radiation patterns:

ECC = \int_0^{2\pi} \int_0^{\pi} F_1(\theta, \phi) F_2(\theta, \phi) \sin(\theta) d\theta d\phi

DG = \frac{\left( \sum_{i=1}^N |F_i(\theta, \phi)|^2 \right)^2}{N \sum_{i=1}^N |F_i(\theta, \phi)|^4}

where:

Once the ECC and DG have been calculated, they can be used to assess the performance of the MIMO array. A lower ECC indicates that the antenna elements are less correlated, which is desirable for MIMO systems. A higher DG indicates that the antenna array is better able to resolve multiple signals arriving from different directions, which is also desirable for MIMO systems.

Here are some additional tips for calculating ECC and DG from far-field radiation patterns:

ECC and DG are important parameters for evaluating the performance of MIMO antenna arrays. By calculating these parameters from far-field radiation patterns, engineers can design MIMO antennas that meet the specific requirements of their applications.

I have never used the periodic structures function. The feed is not periodic, so I would not expect that you could use a periodic solver.

I want to use metamaterial like as the image attached.

I am confused about how to apply boundary conditions in CST while designing a unit cell. Is it (unit cell along the x and Y axis and open add space along the z-axis) or is it ( magnetic field (Ht=0) along z-axis, electric field (Et=0) along y-axis and open along x-axis) in this case open boundary is the only option not the floquent mode.

Thankyou for the inputs mam Smrity Dwivedi

In short the answer is no. For a given aperture size you are stuck with the diffraction limit. (the lambda / pi D term). A metamaterial lens may make it practical to use a larger aperture than would be possible with standard optics. (Cheaper, simpler, fewer components) and you can win that way. However, at the same aperture diameter the diffraction limit is the same. There are tricks for getting beyond the diffraction limit such as MIMO and a metamaterial lens might make doing those tricks more convenient or practical, but there is nothing fundamentally different. Anything you can do with one you can, in principle, do with the other.

No, it is larger. That definition is for the distance where the wave-fronts appear close enough to spherical for practical purposes, which is when the distance from all radiating points on the antenna to any single point on the sphere don't differ by more than 1/8 wavelength. For antennas that are smaller than a few wavelengths across, the reactive fields, that contain stored energy that doesn't radiate, reaches out a few wavelengths, resulting in the reactive near field, which has a larger radius than calculated by your formula. In this region transformer coupling or capacitive coupling would be more significant than radiative coupling.

These reactive near fields contain stored energy that is used (by Chu) to define the minimum Q or maximum bandwidth of a "small" antenna (that doesn't have any losses other than radiation or mismatch).

Sheikh Shafaet Islam First of all, remove the overlapping of PerfectE boundary with Radiation boundary. Then you can alter the mesh in analysis ->options->initial mesh options. Fix a mesh size that is less than the permissible value of student version.

Kindly check the attached file. It is available in HFSS help.

thank you so much all. i resolved the problem by just changing the antenna structure a litte bit.

There are a few possible reasons for negative gain for CP antennas in HFSS:

Here are some specific things to check if you are getting negative gain for a CP antenna in HFSS:

If you have checked all of these things and you are still getting negative gain, it is possible that there is a bug in HFSS. In this case, you can try contacting Ansys support for assistance.

It is important to note that a negative gain does not necessarily mean that the antenna is useless. For example, CP antennas with negative gain are sometimes used for near-field applications, such as RFID. However, if you are designing an antenna for a long-range application, a negative gain is undesirable.

It has 16 dipole antennas one above the other, all fed in phase with each other,

To plot a gain versus frequency plot in CST Studio while designing an antenna, you can follow these steps:

CST Studio will generate a plot of the gain versus frequency for your antenna.

Here are some additional tips for plotting gain versus frequency in CST Studio:

Greetengs! Do you use a voxel model for human body or it is a polygonal model? And what do you mean "6 mm above the human body", I can't understand where is this distance on the picture?

I have two ideas so far: use local coordinates in order to position your antenna respectfully to body or try to make it manually (but this could be really unaccurate).

Greetings you can follow Professor. Ganesh Madhan, MIT Campus (Anna univ.) publications for the same.

There are many ways to prove that you are getting the polarization you want. Straightforward methods include a simulation of the antenna or an anechoic chamber measurement, in both cases you can determine the far-field radiation and axial ratio. Axial ratio would not tell you if you have right-hand or left-hand circular polarization, but the radiation patterns will reveal that.

Another method is to study the feed network of the antenna, circular polarization is typically obtained by exciting two orthogonal linear polarizations. You can also study the fields and current excited by the antenna.