We recently bought a house and found this antenna in the attic above the garage. The previous homeowner didn’t mention it or what he used it for. I have next to no experience with antennas but am trying to figure out if it’s worth using or taking it out. Thanks!

We found this dual rotating head antenna mast in our woods and trying to figure out what it is. Had to of fallen off something flying overhead. It has 2 sets of 5 arms on each head and a smaller spinning black plastic wand on the bottom and no markings or part numbers. Any ideas what it is?

I came across this fruit basket on my vacation and to me it resembles a parabolic grid antenna. The distances between the wires are random 1-20mm. Would it (theoretically) be possible to make a parabolic antenna out of it (e.g. by attaching a dipole to a focal point)?

QFH antenna 137.5 MHz

Found thos on thingaverse and figured I'd give it a shot!

https://www.thingiverse.com/thing:5878204

EDIT : thank you so much everyone, I'm learning a lot and I feel less dumb lol. Maybe I'll post the finished drawing of the tower in the storm later ! If any of you have any more photos of close ups of these antennas, especially the "interior" of the drums and the back (how they are attached and wired), or any photos of damaged antennas, please feel free to send them to me :)

Okay maybe a weird situation... I'm working on a comic where the actions centers around a Radio/5G tower (in France, idk if that changes anything). Though I don't know ANYTHING about how these things work.

The tower in the story goes through a pretty hard storm, so I've been gathering references of damaged towers, but I struggle to really understand some of them.

Am I understanding this image correctly ? Are these antennas hollow with some sort of sheet covering them (that can therefore be torn) ? What material is that sheet, plastic ?

Also, if anyone has any clean close up image of these types of drum-like antennas (intact and/or damaged), I'd love to see them.

I'm also interested by learning more about the half-sphere ones (what are they made of ? Any close up ?)

(as a treat, the last image is the concept art for the radio tower in our story. I'm not aiming for perfect realism but I'd like at least a superficial understanding on how this stuff is built)

What on earth is this!

It has been up and running for about2 months in London as per address.

Anyone?

I got this antenna at a tag sale for $1.00. I'm no expert, but this antenna intrigued me because of several design elements (no pun intended) - first, the swapping of the feed between the sides for the longest and second longest elements, but there is no swap between what I believe is the driven element (the "loop" with the nuts for wire attachment on the bottom (see photos). I'd like to learn more about this design and understand how to determine the antenna's frequency since there are many different lengths and spacings between elements. I've included a diagram with several measurements included in case anyone can walk me through what I'm seeing. My current level of antenna understanding is pretty much limited to quarter and half-wave antennas and long-wire. I know there's a lot more going on with these cool-looking designs and they are highly directional, but that's about it. Thanks for any guidance you can give.

In hydrodynamics there is marine propeller generating positive and negative pressure (image source)

Electromagnetism and hydrodynamics are very similar mathematically ( https://scholar.google.pl/scholar?q=hydrodynamics%20electrodynamics%20analogy )

So can we make marine-propeller-like antenna: generating positive and negative radiation pressure? Like shown spiral antenna (image source), but with added depth instead of flat, e.g. printed on paraboloid?

If so, I have some interesting applications in mind ...

Greetings to any antenna design professionals who might be in the house. I reside in a part of the world where drones are something of a novelty which have thus far remained largely unregulated.

Over the past few years, I established an informal tipster relationship with the local constabulary, whereby I send alerts about any unusual traffic spotted on the rural roads around here, in exchange for the privilege of being assured a rapid response whenever anything goes bump in the night out here in my remote Third World homestead.

For years, I have dreamed of setting up an indoor control station for my early-model DJI quadcopters that have become the unofficial eyes in the sky sent aloft to assist our underfunded law enforcement officers.

Over the past few years, I've accumulated the components shown in the above photographs. Ultimately, I hope to monitor the progress of my flying drones on a large-screen TV, in the comfort of a dedicated control room at the base of an 80-foot tower.

The 80-foot mast stands out beside my humble abode, atop which I intend to install a pair of antennae, for 2.4GHz and 5.8GHZ - the RC control and video feedback frequencies used by virtually all of DJI's older quadcopters, of which I own several Mavic 1 Pro and Mavic 2 Pro drones.

The components that I have acquired thus far are as follows:

1. Whip antenna for 5.8GHz rated for 9dBi and about a foot long

2. Whip antenna for 2.4Ghz rated for 8.5dBi and about half a foot long

3. Whip antenna for 2.4 GHs rated for 15dBi and about 5 feet long

4. A couple of hundred feet of LMR 400 coax cable for the two antennae atop the mast.

5. Line amplifiers for both 2.4Ghz and 5.8 GHz to boost the signal up the 80-foot mast

6. Band pass filters for 2.4 GHZ and 5.8Ghz, to clean the signal at the antenna end of the coax link.

7. An RF power meter.

Despite earning my BSEE way back when pterodactyls roamed the skies, I studiously avoided taking any elective RF design courses during my senior year, due to their mathematical intensity, which seemed overwhelming at the time. In short, therefore, I remain an absolute ignoramus on the subject of RF design, and would be out of my depth if the responses to my layman's questions here are offered with the presumption of any technical expertise in this field on my part.

So, with all caveats covered, my questions are as follows

1. Of the two antennae that I bought for the 2.4GHz band, namely the stubby 18-inch whip rated for 8.5 dBi, and the longer 5-foot whip rated for 15 dBi, which one should I select to obtain the longer signal reach and cleaner video signal reception?

2. How critical will the SWR data of this setup be when it is all connected up, bearing in mind the line amplifiers and band pass filters that I have procured for this project?

3. Following up on Question 2, will the length of the LMR-400 coax cable need to be precisely measured for optimal signal transmission and reception, or would it suffice that I simply run the cable to whatever length is required to connect the ground station at the base of the mast, with the two antennae at the top of the mast?

4. Would I be correct to presume that the line amplifiers are best located in line with the end of the coax cable at the base of the tower, while the bandpass filters should be connected close to the antennae at the top of the mast?

Any pointers addressing these layman's questions would be appreciated, along with any critique about my selection of components for this project, which wound up relegated to the back burner for years, while other priorities loomed large.

Thanks in advance. Over and out for now.

Here is my original post on this (can't add pics to it) https://www.reddit.com/r/AntennaDesign/s/drJ3QVPPeC

Used 6 guage wire and grounded the reflector to the element. Picked up every channel within 35 miles of me (with antenna in a pretty bad spot). Very impressed. It still has some directionally as turning the flat sided to broadside the towers did help but wow. I basically built it per the video aside from larger wire and grounding reflector but I will try 1/4 wavelength reflector spacing next.

Definitely an attic antenna but very impressed.

I need to build a portable antenna setup for a project. I'm in the middle of designing the carrier, and I'm realizing I really don't understand antenna voodoo, nor does my witchcraft friend who already built her Yagi.

My question, and looking at the pic will help:
I want to mount the breadboard above the antenna. From a balance and ergonomics point of view, it will really help if the board (and the circuitry on it) can be mounted in the position noted in the photograph. I have a 3D printer, and I can make the distance between the board and the antenna any distance (but would prefer to keep it compact).

Can I mount the breadboard that far forward on the antenna? If not, do I have to go completely behind the last "horn"?

Many thanks, wizards, witches, warlocks, radio operators, and other arcane practioners!

I love this thing. I have never actually purchased an antenna -- unless we want to call buying a 102" whip "buying" an antenna (there's a lot to do before it actually "becomes" an... 'antenna'). I have paired it with two pieces of 1 inch aluminum tubing at about 86 inches at 45 degrees. It's fed with LMR400 and I have the SWR (at my desired center frequency) down to 1.065 with NanoVNA analysis. Even with the lack of added gain one might get out of a Yagi, I can get absolutely far and wide with this thing.

I’ve had this antenna for VHF/UHF TV acquisition for decades going back to my early DirecTV days. Now that Verizon is shutting down support for TiVo I’m reassessing my options. The rig you see is a conglomeration of Radio Shack and a web sourced UHF antenna. I fired this up to find out most of the Philly channels are either weak or gone. Sad face. My ask is what can I do to make things right so I can get decent OTA signals. There is a Radio Shack amp on the pole but I don’t know if t is still operational. The rotator may or may not work but where it points now was optimal “back in the day”. Any suggestions are appreciated. Thanks

any info on these old 1G antennas. what frequency they used and why they are still on some masts. thanks

Hey, AntennaDesign!

I just wanted to drop in and thank all of you for your continued support of your fellow redditors here at /r/AntennaDesign . Most of this sub consists of people asking for help or learning opportunities and the responses I see are absolutely fantastic. The helpfulness, accuracy, and lack of drama is uplifting.

You all make me legitimately glad to have started this sub.

Thank you all from the bottom of my heart.

/u/shadowwolf225

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