Help with finding/building two antennas, 0-30MHz and 1700MHz-6000MHz - Page 1
Forum section: electronics / rf-microwave

author: TERRA Operative
author_rank: Super Contributor
timestamp: January 28, 2020, 10:11:50 am
content: So I recently installed an electrosense system on my roof. It uses a discone antenna connected to an RTL-SDR plugged into a raspberry pi to survey the RF spectrum from about 30MHz to 1766MHz and is working really well.https://electrosense.org/Just the other day, I received an extension card that does some fancy frequency shifting to allow the connection of two extra antennae to expand the frequency range from 0Hz (Or thereabouts) to 6000MHz. This means I'll have 3 frequency bands to cover. 0-30MHz, 30-1766MHz (I have this antenna) and 1766-6000MHz.So my question is, for the 0-30MHz VLF band, I think I could probably use pretty much just a long bit of wire strung up on my roof, or something like these PCB types? (Maybe this type is better to avoid having wire everywhere during typhoon season here in Japan?.....)https://www.ebay.com/sch/i.html?_nkw=vlf+antennaIf I were to go for a bit of wire, what are the best practices for something like this? I need to get it into a standard SMA connector on the board, same type of connector as a Wi-Fi antenna.I have access to a wide range of connectors, adapters, insulators and wire etc etc in Akihabara so if any greybeards can tell me the secret ways of VLF antenna design, let me know.And for the 1766MHz-6000MHz band, is there even an omnidirectional antenna that can do this that isn't military or NASA grade hardware??I'm 99.999% certain that I won't be designing or making that one myself, so it'll have to be purchased from somewhere.

author: vk4ffab
author_rank: Frequent Contributor
timestamp: January 28, 2020, 10:41:25 am
content: You need wire inthe air.more equals betterer. A half wavelength at the lowest frequency of intrrest as a guideline. Say 3mhz as low enough, then 40 meters of wire, or as much as you can fit in your yard. That will kind of cover am broadcast to 30mhz. Vlf is a different beast to sw and hf.

author: geggi1
author_rank: Frequent Contributor
timestamp: June 11, 2020, 04:20:47 pm
content: I know this is a bit late reply but in case you still have not got any antennas here is my suggestions.For the 0-30Mhz google "mini whip active antenna"For the 1,7 to 6Ghz I would look for a logperiodic PCB antenna or maybe 2 of them to devide the frequency range. This antenna is directional so you might have to build some kind of rotor to rotate the antenna.

author: radiolistener
author_rank: Super Contributor
timestamp: June 12, 2020, 05:20:49 am
content: yes, mini whip with good RF choke near antenna will be a good choice. But if you want to receive weak stations, you will need full size resonant antenna with narrow bandwidth. Also you can use some piece of wires with matching tuner.

author: Lord of nothing
author_rank: Super Contributor
timestamp: June 12, 2020, 04:26:02 pm
content: HiWhat is need for a powerfull HF Antenna? Just some steel wire?

author: Grandchuck
author_rank: Super Contributor
timestamp: June 12, 2020, 05:09:53 pm
content: Copperweld (TM) wire is sometimes used ... copper coated steel wire.

author: TERRA Operative
author_rank: Super Contributor
timestamp: June 13, 2020, 10:03:51 am
content: I've picked up one of the 'mni-whip' antennas from ebay which I'll stick in a bit of PVC pipe and mount on the mast.I just need the 1.7 - 6GHz one now..