r/AntennaDesign

What antenna can I set up with no trees?

I am looking to gain access to at least the 20m and 40m bands.

My backyard is about 65 ft by 65 ft. The orange dot is where I have a feed line coming out of the house. Currently I have a 40m ham stick painted gray, on the PVC greenhouse(white circle) doesn't work really well. Structure has power and is ~9 feet tall, all plastic. Between the orange dot and green dot is an underground conduit 1 1/2 size. The dots around the yard are small fruit trees about 7 foot lollipops.

I have a 20 meter dipole and a 2m jpole in the attic. The dipole has a lot of qrm out the radio, I seldom can hear anyone.

This is a new neighborhood and we just avoided having to create an HOA so I don't want to give the neighbors any reasons to be mad.

u/baconradiocontest — 23 hours ago

▲ 21 r/AntennaDesign+2 crossposts

28 GHz two element patch antenna array in HFSS, 26.5 GHz and 28.9 GHz resonances, -28.19 dB return loss

u/No_Crab_4284 — 4 days ago

▲ 11 r/AntennaDesign+4 crossposts

Free open-source PO/PTD tool for dual-reflector antennas (GNU Octave/MATLAB)

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.

youtube.com

u/Reflector_Antenna_87 — 5 days ago

▲ 16 r/AntennaDesign+3 crossposts

Help: Sleeve dipole antenna 868mhz

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.

u/Limp_Reputation471 — 6 days ago

▲ 9 r/AntennaDesign+1 crossposts

Got an antenna your modeling programs disagree about?

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

reddit.com

u/Zealousideal-Pen9091 — 6 days ago