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Questions tagged [antenna-modeling]

Use for questions about using antenna modeling software to simulate an antenna system and determine its gain and radiation pattern.

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NEC2: What is the difference between currents and charges?

Questions What is the difference in meaning between currents and charges in an NEC2 simulation? How would you reason about charge and current density in your design to better understand (and tune) ...
KJ7LNW's user avatar
  • 775
1 vote
1 answer
57 views

How does a yagi beam propagate?

Why does the power density of yagi antenna beam propagation diagrams increase as the distance to the source increases? Shouldn't the signal get worse as the distance increases or does that only happen ...
mkocrehjuko's user avatar
5 votes
2 answers
84 views

Metal panels in 4nec2

I have a number of immovable metal roofs that are near my antennas. I'm wanting to model how these affect my antenna performance. Is there a way I can put a metal plane into my models on 4nec2?
David Findlay's user avatar
2 votes
1 answer
207 views

Impedance of Yagi boom model in NEC

When modelling a Yagi in NEC the radiation pattern is essentially identical whether a conductive boom is included or not, see pictures below. An explanation says this is a limitation of the method of ...
butterflypea's user avatar
2 votes
2 answers
201 views

Why does my 7 MHz antenna trap have an SWR of 8?

I made a 7 MHz antenna trap. On testing it the cut-off point was 6.687 MHz which is about right but the problem I've got is the SWR was an 8 and wouldn't go down to a resonant SWR. What have I done ...
chris cutting's user avatar
1 vote
0 answers
66 views

Does 4nec2 allow SY variables/formulas in integer fields?

I've looked at the various guides I found on the 'web, and I cannot find a single example of a 4nec2 deck that has a variable or formula in one of the integer fields. But at the same time, none of ...
Maury Markowitz's user avatar
1 vote
2 answers
59 views

GS cards in NEC decks

I'm trying to understand the use of GS cards in NEC2 decks. The documentation is rather vague! Consider a basic stack: ...
Maury Markowitz's user avatar
2 votes
1 answer
89 views

4nec2: What does "#12/in" mean?

I've been seeing this #nnn pattern in SY cards a few times, but I can't find any mention of it in the documentation. I'm ...
mcmayer's user avatar
  • 123
4 votes
1 answer
405 views

How to correctly model a small helix antenna

I am getting weird results trying to model a small 433 MHz helix antenna similar to this one with 4nec2: In particular I am not able to obtain a resonable SWR value. This is the antenna an example of ...
stenio's user avatar
  • 143
3 votes
3 answers
836 views

How to make ELF-ULF antenna myself?

I want to check the EM pulse between 3HZ-3kHZ with N9041B UXA Signal Analyzer,it seemed the only antenna I can use is Aaronia MagnoTRACKER,but the price is not affordable. Then I plan to make ELF-ULF ...
kittygirl's user avatar
  • 650
2 votes
1 answer
74 views

How Accurately Does NEC-based Antenna Software Calculate Vertical Monopole Antenna System Radiation Efficiency for "Far-Field" (Only) Conditions?

A common belief among amateur radio operators is that the radiation efficiency of a vertical monopole driven against the Earth is much less than that of an elevated, horizontal dipole of the same ...
Richard Fry's user avatar
  • 2,932
1 vote
1 answer
87 views

4nec2: simulating the effect of walls over the far-field pattern

I live at the 15th floor and am interested on a pair of window-mount antennas for the 40 meters band: a top-fed vertical; and a loaded monopole, which I've already used with pretty decent results. I'd ...
Rodrigo Magalhães's user avatar
1 vote
1 answer
79 views

Where can I find London borough outlines for SPLAT!

Splat seems like it's a great tool for modelling what RF coverage I should have. It can create a nice circle around me, after I download topology data from USGS, namely SRTM-1. But when the coverage ...
Thomas's user avatar
  • 754
0 votes
1 answer
56 views

4NEC2 shortening factor "x"

I read on pg5 of Antenna Simulation with 4NEC2 about shortening factor "x". It is very specific and I can't figure out how to use it in a general nec file. It sounds like SY x=0.907 in the ...
ruggb's user avatar
  • 111
1 vote
1 answer
217 views

How to model a curved element in 4NEC2

I am in kindergarten with 4NEC2 and trying to model a Gray-Hoverman TV antenna. I have someone else's model and understand most of the file parameters. I have added VHF elements that have S curves at ...
ruggb's user avatar
  • 111
0 votes
1 answer
116 views

Software to model autotransformer matched end fed dual band, 4nec2?

I have several ground independent dual band antenna of different makes, but they all have the same type of matching circuit to make them ground independent / radial-less and match say 5/8 elements, ...
Hayden Thring's user avatar
2 votes
1 answer
362 views

Mutual impedance of two parallel dipole

Good Morning all, I want to calculate the mutual impedance of two parallel dipole. The first hypothesis is to assume that the dipole 2 is in open circuit, nothing difficult here I knew how to do it ...
Tarik L's user avatar
  • 45
4 votes
0 answers
876 views

4NEC2 radials & grounds

Teaching myself 4NEC2 and have most of it under control, which is good. Regarding radials & grounds, i've been learning the "rules" NEC(2) has, summarised below. 4.1. Free space. In the ...
t252's user avatar
  • 697
2 votes
2 answers
3k views

Modelling a "fan dipole" or "fan inverted vee" using EZNEC - unexpected result

I plan to put up a "fan inverted vee" but for various reasons I will not be able to take it down, adjust wire lengths, put it up, test, etc: I will basically have to cut the wires, put it up and leave ...
RiskyScientist's user avatar
1 vote
1 answer
278 views

Modeling a multiband Yagi in 4NEC2?

I tried to model a multiband yagi. I added radiators for 10-15-20M, and reflectors spaced .15 wavelenghts away. This gave a nice result with three sharp dips in SWR in the 10-15-20M center frequencies....
hjf's user avatar
  • 1,219
2 votes
1 answer
566 views

How to model my rooftop vertical on 4NEC2?

A few months ago I built a coil loaded vertical, and put it on my rooftop. My roof is made of corrugated metal, so I connected GND to it, to act as a ground plane (or is it a counterpoise?). With some ...
hjf's user avatar
  • 1,219
5 votes
2 answers
1k views

Modelling a folded dipole

I am looking at using NEC to model a $0.5\lambda$ rectangular folded dipole, for closely spaced larger sides (choosing a separation of $0.01\lambda$). In Antenna Theory, Analysis and Design by ...
pymekrolimus's user avatar
3 votes
1 answer
177 views

Do Far-Field Radiation Patterns/Gains of NEC Software Accurately and Always Show the E-M Fields "Launched" by Vertical Monopoles?

Judging from posts on the Internet, this belief commonly is considered to be valid. But what is the correct answer?
Richard Fry's user avatar
  • 2,932
2 votes
1 answer
155 views

Convert NEC antenna file to .out-file for Wattwächter

I've just wrote a NEC Antenna file of my longwire with xnec2c on Ubuntu. To calculate protection distance with Wattwächter, I need an .out-file. Protection distance means the safety distance for human ...
Tobias M.'s user avatar
4 votes
2 answers
208 views

Basic antenna matching theory?

I'm fairly new to antenna matching, other than having built a base loaded vertical. I'm also new to EZNEC and I tried to simulate an horizontal loop. I arbitrarily chose a 10x10M loop, so I added 4 ...
hjf's user avatar
  • 1,219
3 votes
1 answer
297 views

How to simulate two antennas in 4nec2

I need to simulate 2 helix antennae placed side by side, and see the resultant radiation pattern. But after adding the second antenna with a separate and when I try to simulate 4nec2, only simulated ...
Yaaseen Mohamed's user avatar
5 votes
1 answer
137 views

How to model passive elements when simulating an antenna?

So I started writing an antenna simulator program to design antennas for my needs. To calculate the electric field vector at every point, I split the active element of the antenna into a large number ...
atomd's user avatar
  • 51
0 votes
1 answer
702 views

ADS Simulation: How to model an antenna in a simple rectifier circuit?

As titled, I'd like to explore the output power of a simple diode-based rectifier circuit, excited by an antenna (assumed to be 50 ohm impedance). Please give me some advice as to how to do this. It ...
Minh Lam's user avatar
  • 117
1 vote
1 answer
1k views

Raising height of inverted V by 2 meters

Now that I have a working G5RV Jr. and have had some good luck with DX (Croatia and Venezuela on 20m, Morocco on 40m from Michigan at 100w output), of course I want to mess with the configuration. It'...
K8KV's user avatar
  • 377
2 votes
1 answer
87 views

How to consider the influence from the PCB that a small antenna is mounted on?

The small antenna itself has an $S_{11}$ of -3 dB around MICS band (verified with simulation and network analyzer). In application, the antenna is mounted on a transceiver PCB of 30*15*0.8 mm which ...
luw's user avatar
  • 57
3 votes
1 answer
2k views

How do I specify that wires are connected in 4NEC2?

I've been trying to get acquainted with the 4NEC2 antenna modeling program. Perhaps this is obvious, but it's not clear to me that wires with one end in the same place are connected. I'm attempting ...
Rodney Price's user avatar
3 votes
1 answer
428 views

Mathematica notebook for NEC2 (NEC, Numerical Electromagnics Code)

Are there any open source Mathematica notebooks that interface with NEC2? I am primarily interested in plotting the NEC2 results from Mathematica.
ZJL's user avatar
  • 33
5 votes
2 answers
1k views

4NEC2 - Radiat-eff. vs. Radiat-power

In the output from 4NEC2 the input power is 100 W. On the left, in blue text, is Radiat-eff. which equals 15.41%. On the right is Radiat-power which equals 94.88 W. I would expect either the first ...
user34299's user avatar
  • 153
8 votes
5 answers
7k views

Does mounting a ground plane antenna upside down change the takeoff angle?

A typical gain pattern for a quarter wave ground plane antenna is: Image from a similar question and see watermark. For a situation where the signals of interest are below the antenna in elevation (...
hazzey's user avatar
  • 229
1 vote
1 answer
237 views

4NEC2 - Antenna outside Pattern

I am very new to 4Nec2 and need to do a simulation of a half-wave dipole antenna for 433 MHz. I've read a couple of tutorials and I understand most of it so far, still, my simulation doesn't make ...
ffritz's user avatar
  • 113
3 votes
2 answers
866 views

Antenna gain vs. radiation efficiency in 4nec2

I'm trying to evaluate HF antennas for low angle performance to pick from a list of designs that will fit in my limited space. I'm using 4nec2 to simulate them and compare the patterns. When your ...
hamateur_sandwich's user avatar
2 votes
1 answer
338 views

How do I simulate a receiving antenna in EZNEC simulation tool?

I have a situation where I need to find receiving antenna impedance when it’s $\lambda/2$ distance from the transmitting antenna. Both are dipole antennas. Is it possible with EZNEC?
Shiva Mudide's user avatar
5 votes
4 answers
7k views

How to produce a NEC antenna file (and what software to use it with)?

So I'm really trying to get to grips with antenna radiation patterns, and more importantly things that are to close to the antenna that might interfere. I've downloaded Qantenna and 4NEC2 to try and ...
FraserOfSmeg's user avatar
8 votes
2 answers
966 views

Simulating two antennas (transmitter and receiver) using 4nec2 tool

I am trying to find near field mutual coupling affects between two antennas - one being transmitter and other being receiver. The receing antenna is fed with very little voltage (I think, if I don't ...
Shiva Mudide's user avatar
6 votes
3 answers
1k views

Correct number of elements in 4nec2 antenna simulation

I am designing a 1.25-wavelength dipole antenna with the 4nec2 software. What I noticed is that the input impedance of antenna is changing greatly when I change the number of segments. How many ...
Shiva Mudide's user avatar
2 votes
1 answer
2k views

Is there a 4:1 current balun model for 4nec2?

I don't seem to be able to find the data to enter a 4:1 current balun in the 4nec2 software. Has anyone found or written one? I am building a 75 Ω fed OCFD and need to model the radiated patterns, ...
colin martin's user avatar
9 votes
1 answer
257 views

Antenna modeling on non-uniform terrain

I'm interested in modeling the radiation pattern of wire antennas for hf before I invest the resources necessary to erect the antenna. I'm familiar with tools such as 4nec2, but from what I can tell ...
W5VO's user avatar
  • 1,901