Antenna starter parts? - Page 1
Forum section: electronics / rf-microwave

author: rthorntn
author_rank: Frequent Contributor
timestamp: October 28, 2024, 07:08:10 am
content: Hi,Having just ordered a LiteVNA64 so I can make some antennas for meshtastic AU (919.8MHz) it occurred to me that I probably need some starter components, I have no antenna parts, what should I order, I'm thinking connectors, coax cables, rods, solid wire?I'll probably make a omni and perhaps some sort of sector antenna to go on my roof.Any help will be much appreciated.Thanks!

author: selcuk
author_rank: Frequent Contributor
timestamp: October 28, 2024, 08:19:16 am
content: I bought a 24 pcs kit and some other frequently used adapters from the link below after buying the litevna. But you may not need most of them if you are going to use SMA antennas only.https://www.aliexpress.com/item/1005005081003986.htmlYou may need RG405, RG402 or RG316 cables and related SMA connectors. Some connectors are for soldering and some for crimping.

author: DaJMasta
author_rank: Super Contributor
timestamp: October 28, 2024, 05:09:27 pm
content: There can be a pretty wide selection of options for antennae and an even wider selection of parts for them, so maybe you can narrow it down to a couple of types to figure out what you'd need.It sounds like your application is usually smaller antennae, so SMA is a good route as a primary connector (and RP-SMA is very common for antennas, so have at least a pair of adapters), but these cheap ones don't necessarily have great tolerances, so I'd get a good quality port saver (SMA male to SMA female) to protect the ports on your VNA from any connectors with issues/wear. If you're trying your hand at PCB antennas, I'm a fan of using semirigid or rigid coax as the interface and soldering it directly to the board - so some semirigid SMA cables cut in half are a reasonable, cheap starting point. If you want to be connectorized, then some RA and top entry SMA connectors would be a good choice (usually female, since cables are usually male to male). If you want to be constructing parts from wire, you want some reasonable gauge solid core wire with appropriate material/coating to prevent oxidation. You probably don't need substantial hardware or pipes for aerials just because at nearly 1 GHz, the size may be a bit small to use the construction style used for VHF or HF bands.

author: rthorntn
author_rank: Frequent Contributor
timestamp: October 28, 2024, 08:22:14 pm
content: Thanks.Would you have any recommendations for a good beginner omni and also a sector (around 60°) design, size doesn't matter, great gain, a tall onmi to get higher up (lots of buildings around and 915 is quite L.O.S and I can already see that the cheap 5cm coiled rubber ducky antennas give me no neighbor nodes when I set them up at roof height)?Something easy to tune.If required I have a workshop with a mill and lathe.I'm interested in good step-by-step instructions with pictures.I'm in a metro location, the antennas will go on to the roof of my house, so weatherproof, N-type for external, radio will be in a box next to it?I do have my foundation license so I'll probably build some HF antennas in the future.

author: coppercone2
author_rank: Super Contributor
timestamp: October 29, 2024, 12:59:47 am
content: I mean its anything from essentially precision tin smithing to precision plumbing to precision multi axis machiningyou pick an antenna, develop a work plan and then buy tools that you don't have. its not generic at all.the only generic one is the PCB antenna that can be etched or other planer antenna (copper foil)it goes from a pITA like a dipole to a expert machinist skill like a pipe-work biconicalin microwave frequencies you need to be really precise and its hardthe first "screw this" you will run into is thinking that you can solder, braze or weld something to be 'true' easily. Or that medicore jointery is going to survive the 'bending' you want to do after you build it and nothing is straitCan you precisely drill a hole in a cylinder? can you drill a hole in a cylinder at an angle?

author: coppercone2
author_rank: Super Contributor
timestamp: October 29, 2024, 01:08:34 am
content: more then likely the work is going to come from your build plan, and how it deviates from an ideal build, and how you can fix the RF parameters of what your capable of to get the performance you want.If you read on forums, there is quite a few people that had ambitious plans on big antennas and it resulted in massive fail, and thats perfectly normal and expected given the difficulties of fabricating them. making a nice thing out of metal is hard enough when it just has to look nicegenerally where its kind of a 'fun' cobble is from LF to maybe some VHF. thats where all the 'regular' craftsmanship comes in handy. and even those get extremely hard when you have a higher power levelI got the first tool you can't easily afford without a pack of alka seltzer for the most basic thing : good caliper 18 inches or bigger. and a 2 foot machinists strait edge to see if you are level with your build, and a properly flat table, and height calipers. then you can do a basic mechanical QC of a medium sized antenna . and a precise heavy fixture of some kind to hold it level

author: A.Z.
author_rank: Super Contributor
timestamp: October 29, 2024, 11:59:10 am
content: Quote from: rthorntn on October 28, 2024, 08:22:14 pmAt 915Mhz you'd better have your transceiver up the roof too, otherwise your losses will be pretty highQuoteWell, 915MHz means a Lambda of 32cm, so even some millimeter will have an impact on the tuning, anyhow, did you consider a simple 1/4 wave ground plane antenna ? Size will be pretty small (about 8cm for radiator and radials) and it should be relatively easy to tune, or either you may consider a simple vertical dipole, just space it 50cm or more from the support pole and it will work and give you omnidirectional radiationanother ideahttps://keptenkurk.wordpress.com/2018/03/26/a-lora-868mhz-collinear-antenna/