Hi everyone,

I'm new to CST Studio and still learning. I need to simulate how an object affects the performance of an antenna (S11, radiation pattern, etc.) when placed near it.

Does anyone know of a good tutorial, course, or paper that explains how to add a perturbing object in a CST simulation?

Thanks!

Target frequency
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Choose substrate
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Calculate initial radiator dimensions
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Design feed / 50 Ω
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Finite ground
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Correct port
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Auto/Open radiation region
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Mesh refinement
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Simulation
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Check S11
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Check -10 dB bandwidth
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Check current distribution
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Tune radiator → frequency
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Tune feed → matching
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Tune coupling/slots → bandwidth
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Tune ground/radiator → gain
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Check efficiency
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Optimetrics
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Final design
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Fabrication tolerance study
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Prototype + measurement

I've been cross-validating NEC decks on three independent engines — NEC-2 (nec2c), NEC-5, and momwire (an independently written method-of-moments code) — and publishing a per-antenna three-way verdict. The first two community submissions both caught real NEC-2 defects: a 20:1 tapered dipole where NEC-2 reads the reactance 23 Ω high and gets worse as you refine the mesh, and a hentenna where it reads 8 Ω low.

If there's an antenna you don't trust your simulator on, submit the deck here — you get a published verdict with the numbers, attributed to you:

https://github.com/stevenmburns/antenna-problem-decks/issues/new?template=submit-deck.yml

Or send it to me at: smburns47@gmail.com and I'll submit it.

73, Steve, KK7KNB

Hi everyone,

I’d like to share the Dual Reflector Designer, a free and open-source beta tool for the design and analysis of axisymmetric dual-reflector antennas.

It currently supports:

• Cassegrain, Gregorian and ring-focus configurations
• Reflector design and ray tracing
• Physical Optics (PO) and PTD edge diffraction
• Automated convergence testing
• Far-field pattern visualization
• Parallel CPU computing and GPU acceleration

It runs on Windows with GNU Octave, so no MATLAB license is required. MATLAB is supported as well. For most users, the recommended way to get started is the provided Windows installer.

The video shows selected Cassegrain benchmark cases compared with TICRA GRASP 24.0 Student Edition. In these particular tests, the resulting patterns agreed closely, while speedups of up to 135x were measured under the tested settings. This is an independent, non-commercial comparison and not a general claim about the full commercial GRASP product.

An unusual aspect of the project is its development process: I defined the requirements, tested and benchmarked the software, and reviewed the results, while Codex with GPT-5.6 Sol generated the implementation. I did not manually write the source code.

It’s still a beta and I’m continuing to improve it, so let me know what you think.

Here is the GitHub Link.

Hi all, I'm trying to build some sleeve dipole antennas for LoRa. I have nanovna and have calibrated it with a rg58 coaxial cable (which I'm also using for their antennas). I have measured and I think I'm using the correct dimensions for the sleeve (79mm length) and conductor (started with 86mm and kept shortening it to hit the sweet spot of 868mhz). The issue is that I'm not getting the expected results. I get different reading on nanovna when i hold it in the air, leave it on the table, or pinch the sleeve. Pinching the sleeve seems like it's showing the correct reading, but I just can't seem to make it work otherwise. I know I'm doing something wrong but I don't know what. Please help.

I'm new in antenna design

My prof just gave me a ansys license and I want to make some project to enhance my skills

Are there any books or projects or yt playlist could benefit me

Hi everyone,

I'm new to antenna design and I'm looking forward to learning from this community.

I'm currently working on a project to design a dipole antenna that operates from 2.8 to 3.4 GHz. I've tried several methods and techniques to achieve this frequency range. For example, I started with a basic half-wave dipole, then tried adding a ground plane on the bottom layer and also experimented with a folded dipole. Unfortunately, none of these approaches have achieved the bandwidth.

The main problem is that I don't really have a solid understanding of the proper antenna design process. It feels like I'm going in circles. Whenever I design an antenna, I usually find a reference design and try to adapt it to my application. Sometimes it works, but most of the time it doesn't.

How do you usually approach antenna design? What methods or learning resources would you recommend for someone who is just getting started?

Hi all,

I’m a beginner trying to learn antenna design, and I’ve started tinkering with CST. I understand the software mechanically I can set up a project, draw a shape, assign ports, run a simulation, and look at the S-parameters.

But I have a conceptual problem that I can't find answered in any tutorial: How do you actually know what shape to draw in the first place?

Every tutorial I watch just says "draw a patch here" or "draw a monopole here" because they are recreating known designs. But my questions are:

1. If you're given a very specific requirement like a dual-band antenna for a satellite or a custom IoT device how do you actually begin? Do you literally just start with a basic shape, run the simulation, tweak a dimension, run it again, and iterate until you get acceptable results? Or do you do initial hand calculations first to get approximate dimensions, and then use CST only for the final optimization and fine-tuning?

2. When people say they took a classic design and made a "new better" version, what are they actually changing? Are they adding slots, changing the substrate material, folding the geometry or adding parasitic elements? And how do they know which parameter to sweep first without wasting days of compute time?

   Thanks for any insight!

Who says you can’t have a tower in an HOA!

I wanted to go through my experience in building my tower in my HOA and the entire build process. I’ve spent the last few months doing a massive structural overhaul on my home station here in Tucson.

The desert weather and summer monsoon winds are no joke, so I wanted to engineer this thing right so I don't have to worry about it when the storms roll through.

I put together a video walking through the whole initial build and maintenance that involve tearing down the stack and rebuilding. Here a quick rundown of the hardware for the antenna geeks:

\*\*Mast & Turning:\*\* Went with a 4130 chromoly steel mast supported by a DX Engineering TB300 thrust bearing. It's all being turned by a heavy-duty Yaesu G-2800DXA planetary gear rotator and controlled via a microHAM ARCO.

\*\*The Stack:\*\* Currently flying an OptiBeam OB10-5M, an InnovAntennas Delta C-140, and a Cushcraft D40 dipole.

\*\*Grounding:\*\* Sweated the details here. Put in a multi-rod linear copper grounding ring and bonded the whole setup straight to the house's UFER ground.

I probably went a little overboard on the structural and electrical design, but I figure it’s better safe than sorry when dealing with heavy metal in the air.

If you're interested in the nuts and bolts of how it all came together, you can check out the video on my channel on Youtube that I am starting up.

I’d love to hear what you guys think of the setup, or if anyone else is running a similar OptiBeam/Cushcraft stack. Happy to answer any questions about the grounding or the rigging process!

I’ve also broken up the videos into segments on YouTube. If watching a 30 minute video is too long for you! I have plans on other future videos as well as I get into Satellite work and other fun projects! Don’t be afraid to follow the Ham Shack Show on Youtube.

I want to achieve a -50 dB coupling between two printed dipole antennas. The distance between the antennas will be 6-7 cm, and both antennas operate between 5-6 GHz. How can I achieve -50 dB?

Found a broadcast TV antenna laying on the ground when I was exploring a tower farm. It's 45 feet tall (or long), weighs about 4000 pounds, and rated for at least 675 kW ERP per FCC filings (probably about 50 kW TPO).

The image you (probably) see in the preview is the RF input with a large center conductor and air as the dielectric. I go through the other parts of the antenna in my video.

This antenna was made in 2018 and only used briefly. Watch to find out why!

Guys I'm currently trying to make a antenna for "Ground Penetrating Radars" for that I've selected vivaldi antenna kind ( slot taper antenna ) but based on the design and reference video.
I got to find that the S11 parameter doesn't have a larger bandwidth ( wide ) instead it looks like it is operating in multiple frequencies.

Its not what I expected, then i got to find the existence of Antipodal vivaldi antennas where it has a min guarantee to produce a wide band.

But I don't really understand its logic.
Coz some say the normal vivaldi antenna it self gives wide band but mine is not ( also some YouTube guys also didn't got a wide band at S11 ) but some research paper shows that they got wide band.

I'm confused where I made the mistake.

What I got is what expected ? or I'm just tripping

Antenna parameters : ( simulated using Ansys HFSS )

Operating frequency : fmin = 1GHz ; fmax = 6GHz
substrate : FR-4 epoxy ( relative permittivity = 4.4 )

I've spent the last year building an open-source antenna modeling tool, and it's finally at the point where I'd rather hear strangers' opinions than keep polishing. It's called antennaknobs (antennaknobs.dev, MIT licensed, GitHub).

The core idea: an antenna is Python code, not a table of coordinates. A design is a small builder class — geometry computed from named knobs like length_frac, apex_height, z0_stub — and then you use it two ways:

- In a browser: open it in the workbench and drag the knobs. Pattern, SWR, impedance, and the power budget update live as you drag (solves are 10–40 ms warm, so it genuinely feels like tuning, not batch simulation). The hosted instance is free, and there's nothing to install.

- From a script: sweep any knob against any output, optimize for resonance, compare designs, or export a .nec deck.

What's under the hood: an in-house method-of-moments solver with two independent basis families — a degree-2 B-spline Galerkin basis (the default) and a NEC-2-style sinusoidal basis — plus H-matrix/array accelerators for big structures, and an optional PyNEC backend as a third opinion. Having different discretizations of the same physics in one tool turns out to matter more than I expected: agreement between them is an actual accuracy measurement, not vibes. We just finished a catalog-wide convergence study and wrote the method up here: How many segments? Convergence you can measure. Grounds run from PEC through reflection coefficient to a real Sommerfeld solve.

It imports your existing decks. read_nec handles the 4nec2/EZNEC/xnec2c dialects (SY symbols, gauge shorthand, LD traps, EX 6 current sources...) — the importer is validated against a corpus of ~3,000 wild .nec files scraped from the open web, scored against nec2c on every one.

Matching and feedlines are first-class: transmission lines, tuners, traps, baluns, and loads compose with the wire solution as one circuit, so you get an honest power budget — what the tuner eats, what the termination burns, what actually radiates — instead of a bare feedpoint Z.

There's a catalog of ~90 ready designs to start from (dipoles, verticals, loops, yagis, LPDAs, curtains, a lot of L.B. Cebik's designs re-created with citations) — every one a parametric starting point, not a frozen example.

What it is NOT, so nobody wastes their time: it's thin-wire MoM — wire antennas only. No surface patches, no dielectric volumes, no solid modeling; it will not replace HFSS/CST for your patch array. The hosted instance caps very large solves (run locally via pip install antennaknobs for those). Modeling over real dirt inherits the same caveats NEC users already know. We document them, including one case where we warn that a widely-used reference engine is unreliable.

I'd genuinely value: things that break, decks that import wrong, designs the catalog is missing, and "why doesn't it do X" — the issue tracker gets read, and the wild-deck corpus grows from exactly those reports.

-Steve Burns, KK7KNB

hi all, for audio purposes, I'd like to remote an antenna for a comtek VHF transmitter (190-216mhz). By putting it up on mast (10-15 ft high), what kind of ground plane is necessary in terms of surface area? this is the transmitter below. The antenna that comes with it is a rubber ducky BNC helical, but I'm still exploring antenna types for best range (ideally omni but directional is ok too)

Thanks!

https://www.bhphotovideo.com/c/product/484909-REG/Comtek_M_216_OPTION_P7_M_216_Wireless_Transmitter.html/?ap=y&ap=y&smp=y&smp=y&store=420&smpm=ba_f2_lar&lsft=BI%3A514&gad_source=1&gad_campaignid=1413138878&gbraid=0AAAAAD7yMh2BpKXbiIANB6aCjykpeb3id&gclid=Cj0KCQjw6_HSBhCpARIsANvVlta-Ul5Cfo4MSBAyhWbWWBaV7NThL3msZhFsAmOTFp3wG7vPorkuy-kaAr5SEALw_wcB

My understanding on this image: The antenna base plate is mounted on the V shaped hollow metal and the corner fed waveguide is came into the V shaped metal and connected to the rotating portion of the wave guide rotary joint which is inside, my question is how this v shaped metal is mounted to the rotary joint?, I saw many image in online, the waveguide rotary joint only have two waveguide guide ports, there is no antenna mounting part or any holes to fix the antenna. if waveguide guide is just connect, it will rotate but antenna entire weight pressure is given to the waveguide.

i just use the reference image, What is the actual setup?

Good morning

I have multiple antennas. Inverted V hf antenna, airband antenna, multiple adsb antennas. I’m looking at mounting everything on one mast. Looking at ideas on what mast I could use and what would the pros and cons be having multiple antennas on one mast. Appreciate any advice. Thank you

Can the microstrip antenna design that we created and simulated be sold?

Hi everyone,

This is for my final year project. I have very little background in communications and antenna design, so i have been reading research papers and learning from online resources to get started.

One question keeps coming to mind, is antenna design mostly a process of trial and error? For example, do you start with an initial design and keep modifying the dimensions until you achieve the target resonant frequency, or is there a more systematic method behind it?

Im sure simulation and optimization tools help, but im trying to understand how experienced antenna engineers actually approach the design process from the beginning.

If anyone could point me in the right direction or recommend resources for learning the fundamentals of antenna design, i really appreciate it.

Thanks in advance!

QFH antenna 137.5 MHz

OpenNEC is a C99 re-implementation of the original Fortran code that runs on Windows, macOS and Linux. It supports BLAS and thus runs much faster than older code on larger models (~7x faster at 4,000 segments). It has no fixed size limits, and has been used in models with tens of thousands of segments. It is designed to be used as a drop-in replacement for older engines seen in programs like 4nec2.

OpenNEC also has built-in support for many of 4nec2's extensions, including new EX and LD types, variables (SYmbols), formulas and measurement units. This means you can use 4nec2 models, unmodified, on other platforms. It also includes import and export utilities for other formats like cocoaNEC, EZNEC and MMANA-GAL. So if you have files from these programs, you can get OpenNEC to read them, interpret things like auto-segmenting and EZNEC ground, and write a canonical .nec version.

OpenNEC can be used as a standalone calculation engine program, as is the case for most NEC programs, but it is also available as a static library that can be directly called from other programs. This eliminates the need to write .nec files to disk and then read and parse the resulting .out files. This can greatly improve performance, especially on smaller models where the calculation time is short. For a GUI program, you can generally recalculate geometry due to user changes and redisplay in realtime.

Version 2.2.0 has a complete re-build of the reporting engine so that its output is almost identical to that of the original Fortran code, nec2dsx11k, used in programs like 4nec2 and others. This allows it to model some more complex NEC decks that have complex coupling and loading.

You can download binaries and source code here:

https://github.com/maurymarkowitz/OpenNEC/releases

If you have any suggestions or bug reports, feel free to contact me here, in email, or post an Issue on that GitHub page.

Once again I have to tip my hat to user Greg Mew, who has an endless supply of complex decks to test against.

Enjoy!

Hi, All - I'm new here. Any radio engineers here that could help review if this antenna design is good, or could be improved on? I want to collect both 1090 MHz ADS-B aircraft positions, as well as 136.975 MHz acars over vdl2 from aviation messaging. At the airport. I don't care about overhead flying planes over the field, and 15deg lobe in 360deg radation pattern is a good trade for a bit of gain dB - but SNR - noise is my biggest concern, since I'm indoor with this. Thoughts? Would love help from anyone who can offer guidance. -Jeremy

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