<30Mhz Antenna aka Electric Wire - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: June 29, 2018, 10:11:55 pm
content: HiI will try to receiver more and more <30mhz especially Radio. I know I can use still an Electric Wire, Speaker Wire,...The Question is how to connect to my Upconverter/ SDR? Just solder an Xm Wire Cable to an SMA Plug?How about an Balun does that work, help? If yes how?I know Longwave need several Meter Wire can I make an huge Coil around your Yard?sry Long, Medium, Short Wave is still a Mystery for me when it come to Antenna stuff.

author: Karlo_Moharic
author_rank: Regular Contributor
timestamp: June 30, 2018, 12:14:36 am
content: OK , if you want to recieve ham radio, a great solution is regular copper tubing + PVC tubing , basically you can make a simple and effective dipole. What you do is, you go to your local version of hardware store and you buy one regular copper heating pipe (usually they come in length of 6m) , split that pipe in half, buy 2 copper to PVC adapters, 1 PVC "T" joint and one shorter PVC pipe. Use two copper pipes as your elements and "T" joint and PVC pipe as body of your antenna.Also to make antenna as effective as possible you can buy yourselfe one of this QRP antenna tuner kits off of ebay:https://www.ebay.com/itm/1-30-MHz-QRP-Manual-Days-Antenna-Tuner-Tune-DIY-Precision-Kit-for-Ham-Radio/173088391343?epid=1776326254&hash=item284cdf40af:g:Nz8AAOSwl9BWLtdvSince you will be only receiving you don't need high power tuners.As far as baluns are considered , they don't really affect your SWR , but rather only lower the noise floor. Cheaper solution is to just use a good and short piece of coax.

author: Lord of nothing
author_rank: Super Contributor
timestamp: June 30, 2018, 01:03:47 pm
content: Quotenope the Traditional one.I will receive Digital Radio Romania. The Problem is I have no Antenna with an hight Gain or is popper make.I will use an Wideband SDR. So how about this 2 Products?http://www.bonito.de/antennajet/index.htm1) AntennaJet ASM-300 -> mix 3 Antenna together like <10mhz, <20mhz, <30mhz and slit Signal with 3 SDR.

author: Karlo_Moharic
author_rank: Regular Contributor
timestamp: June 30, 2018, 03:28:32 pm
content: OK , so if I understand you correctly , you wish to receive digital radio signal (inside of HF band) , you will be using general purpose SDR (I'm guessing one of those 30$ ones from ebay). And you wish to know how to setup your antenna system for the best possible coverage.Is that about right?P.S. What amount of money do you have avaliable for this project?

author: Lord of nothing
author_rank: Super Contributor
timestamp: June 30, 2018, 04:23:24 pm
content: I have and HackRF and some other SDR who are not that bad.That amount who is necessary but I am not rich.

author: Karlo_Moharic
author_rank: Regular Contributor
timestamp: June 30, 2018, 04:28:20 pm
content: what is the actual frequency you want to listen to ?

author: Lord of nothing
author_rank: Super Contributor
timestamp: June 30, 2018, 04:32:25 pm
content: I cant say exactly just <28Mhz for CB and some khz for Mid Wave Radio.

author: awallin
author_rank: Frequent Contributor
timestamp: June 30, 2018, 04:34:26 pm
content: Did you look at the 'mini-whip' designs out there?Especially at VLF, LF and maybe lower range of HF your SNR is not limited by the size of the antenna, but rather by all the other EM-noise/crap out there, so the SNR with a small mini-whip is almost the same as with a 10m or 40m or whatever long-wire.http://dl1dbc.net/SAQ/miniwhip.htmla variant of this also made by RA0SMS (available on e-bay?)

author: Karlo_Moharic
author_rank: Regular Contributor
timestamp: June 30, 2018, 05:48:32 pm
content: Try the mini whip (mount it on a mast ,on top of your roof), if that doesn't work build the largest dipole you canor buy 160m yagi (the most expensive option)

author: CopperCone
author_rank: Super Contributor
timestamp: July 01, 2018, 01:38:49 am
content: Quote from: awallin on June 30, 2018, 04:34:26 pmcan you explain some numbers? I heard this before, that atmospheric noise dominates, but I would like a crude empirical explanation if you can.Like if we colonized a radio quiet planet or something, how would those antenna designs change?

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 01, 2018, 09:21:37 am
content: How about this one:https://www.ebay.de/itm/Mini-Whip-active-RX-antenna-for-HF-bands-100KHz-30MHz-RTL-SDR-HAM-receiver/183276628026?hash=item2aac23683a:g:n5YAAOSw2PtaqNw9The need an external Powersupply.And there is a seller who life's near me:https://www.ebay.de/sch/kheinz570/m.html?_nkw=&_armrs=1&_ipg=&_from=

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 03, 2018, 02:25:32 pm
content: I will want discover HF and my Antenna I have sucks. So does anyone here have an recommendation?

author: tkamiya
author_rank: Super Contributor
timestamp: September 03, 2018, 02:45:37 pm
content: You are thinking too much!My HF antenna is like this. Some wire hang about 3 meters high from ground from a tree to house. About 30 meters long. At one end, I have a coax, RG58, I think. Center pin goes to the antenna. Braid goes to ground rod. Coax is about 10 meters long and goes into my lab. There, I just connect it to a proper connector and into a radio.It works surprising well. The impedance is all over the place, so I do not transmit on it, but for receive, it's great.Balun is only needed when you have a coax and antenna is symmetrical. Or, when you know the impedance and you have to change it. In this time of Long wire/random wire antennas, and dealing with wide frequency ranges, matching is not possible with balun. You will need an antenna coupler.For receive only purpose, I wouldn't bother.

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 03, 2018, 02:54:42 pm
content: Does the Polarisation is an issue?

author: bd139
author_rank: Super Contributor
timestamp: September 03, 2018, 02:59:45 pm
content: You don't need a lot for receive. I had pretty good luck picking up very readable SW/WSPR/CW/SSB/RTTY/PSK31 across Europe / East coast US right down to Africa and right up to Iceland with a piece of 7/0.2 wire randomly slacked around the ground floor living room in a built up area of London and rammed in the back of my FT-450D's PL259 with no connector The audio interface to the PC was a USB headset resting on top of the FT-450D. FT-450D wasn't even grounded. Even got a SWL report for Radio Caroline's temporary ham ops off that.It's magic how much you can get with basically shit that is lying around.

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 03, 2018, 03:07:34 pm
content: I will receive Digital Radio without fading out every sec.I got the Romain and Saudi but just for seconds.

author: bd139
author_rank: Super Contributor
timestamp: September 03, 2018, 03:17:13 pm
content: Fading (QSB) is annoying on the HF bands for sure but you get used to it. One reason CW and some digimodes seem to win; they can just about cut through it as it's fading out.

author: Lord of nothing
author_rank: Super Contributor
timestamp: September 03, 2018, 03:28:25 pm
content: Digi Radio + SDR is not that easy to use. The Signal must be very good and the noise floor very low to receive it.Its nothing for "amteurs". I ordered this days more equipment to get a cleaner Signal. Just HF is missing.

author: tkamiya
author_rank: Super Contributor
timestamp: September 03, 2018, 06:40:53 pm
content: No, polarization is not an issue on HF frequencies. It bounces between earth and ionosphere and every time it does, polarization flips. By the time it reaches receiving site, it's totally unpredictable. Polarization is mostly an issue between line-of-sight communications.I have all kinds of receivers here. I'd agree SDR, the stick kind, is not ideal on HF. Addition of Ham It Up down converter makes it somewhat usable. The other method where signal is fed directly to comm line is not usable at all. One of the problem with SDR is that it's such a W-I-D-E band. It has to deal with everything before extracting what is desirable. I had most success with Ham gear like TS930 and TS940 which includes general band coverage receive. I bought them used and broken on Ebay for cheap.

author: bd139
author_rank: Super Contributor
timestamp: September 03, 2018, 07:11:45 pm
content: Indeed. My FT-450D is effectively an SDR. The IF is entirely DSP. The thing has 24KHz of bandwidth on the front end.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: September 03, 2018, 07:36:27 pm
content: Depending on your environment, I'd recommend you a whip too. If you're not just caged in one of those apartment building, maybe with access to some green behind the house, it could be a good solution.I'm using two different Inverted L to transmit from LW to the 80m band; but I get a much better S/N ratio on those frequencies with the whip - and this is what matters for reception. I built the classical concept according to the plans of PA0RDT, but in SMD with an BFQ19S instead of the 2N5109