Best MWDX antenna?

[~SIGINT~]

I purchased the new RTL-SDR L band patch antenna last month so this one is my next project.
https://www.rtl-sdr.com/two-reviews-of-our-new-l-band-patch-antenna-stock-update/

As with yourself, I am primarily DC to 30 MHz and 220 to 400 MHz (UHF MIL and SATCOM). I ventured into ADS-B (1090) in 2018. ADS-B is Automatic Dependent Surveillance - Broadcast and are ground & aircraft transponders including flight data. Essentially, the high frequency version of HF-DL or ACARS. This is what the airspace around my house looked like in September 2019.



Now I am curious to look at the GPS band, INMARSAT and Iridium space with the SDR.

[RobRich]

I thought about ADS-B back when the RTL-SDR landed. I just never got around to it. Some day perhaps.

I largely dropped out of the UHF scene when public services and similar went digital.

Be careful or next you might have a Ku dish on a motorized mount…. and looking for somewhere to put the C-band.

[~SIGINT~]

Well, a Ku antenna kind of already exist in the front of the house but it's busy receiving DTH satellite TV service. There are some interesting Ku LNBs mounted in tin cans which work for antennae in that band. For UHF, I only listen to the military stuff in the 220 to 400 MHz band, including the UHF SATCOM.

[RobRich]

Not sure when he started offering them, but ra0sms now has a flag/pennant antenna kit on eBay. :)

https://www.ebay.com/itm/201553084711

Same but with an 1-4MHz bandpass filter.

https://www.ebay.com/itm/202274557903

[RobRich]

My second active mini-whip arrived. Now to take a portable to the backyard and hopefully find a couple of relatively RFI quiet spots to place them.

I am a little more concerned about placement than usual as small active verticals are essentially e-field probes. Even a foot or two difference can change coupling to local noise fields.

Get them deployed, then see how well my phasing unit can effectively utilize the small array.

[ThaDood]

JTA still swears on using the W.O.G., (Wire On Ground.), for RX'ing LF and MW super quiet signals. Hopefully, that may happen this Fall since, thanks, (Or no thanks!), to Biden, all gas line projects around the property here have been put on either a prolonged, or indefinite, hold. I have hundreds of feet of trashed RG-11 rigid coax, with tough PVC outer jacket. Useless as regular coax, but that solid aluminum outer conductor could make for a kick-ass antenna. Stay tuned!!!!!!

[RobRich]

I used an 148' run of RG-6 as a wire-on-ground for years. Fed the center at one end, and shorted the other end back to the shield. I am not sure there was any improvement over just a piece of wire, but I had lots of coax going unused.

Fed it straight, with an 1:1, and with a 4:1. Did not seem to make much difference IMO. I went with a straight feed. No common mode choke at the feedpoint, either, so the feedline shield was the other part of the antenna. Worked okay enough for my purposes from MW through mid-HF at the time.

[~SIGINT~]

As promissed, here are a couple of SDRuno screen shots with the RTL-SDR L band patch antenna connected to the RSPduo SDR which I mentioned in reply #90. No issues with reception, and this is with the antenna sitting inside on the window sill.

[RobRich]

Pretty nice for inside. :)

BTW, I was able to quote and view the pics, though note they are not showing up here at HFU. The host might be blocking them at third-party sites.

[RobRich]

Deployed one active miniwhip. Have another one to go. I am using a PA0NHC-derived design built with SMD parts via the Transverters-Store.

https://www.ebay.com/itm/222469570201

I did not bother much with selecting a spot. I just put it at the back lot line away from the house. Mast is a 10.5' fence top rail buried about 3' in the ground. I might extend the height later, but I have to take some care due to tropical weather. I really not too interested in installing guylines, either.

The antenna is working. I am listening to 20m SSB contacts at 0428z ranging from California to Russia. Noise floor on 20m is averaging under -120dB according to my AirSpy HF+ Discovery. Not bad IMO. :)

I am not even using any ferrites on the feedline, and the the coax is only grounded to the base of the mast. It was getting dark outside when finishing up the coax run. I do have a KD9SV RF common mode choke rated for 3000-ohms+ resistance at .5-10MHz back near the receiver.

I intend to ground the antenna at the top of the mast as intended by the design, plus probably install a few ferrites. Maybe tomorrow.

[RobRich]

A quick screenshot of AM BCB. Well, a 725KHz portion of the band to be technical.

https://imgur.com/a/eCcJHWO

Current nighttime mediumwave noise appears to be hovering around -90dB at the bottom of the band to nearly -100dB at the top of the band. From a noise perspective, my community is somewhat rural, but my immediate neighborhood is more like a suburban area.

I am definitely going to need the second active antenna and the phasing unit to sort out the mediumwave jumble. Too bad the phaser only goes down to ~1MHz, but whatever I suppose. I am more of a casual mediumwave listener anyway.

I would do a screenshot comparison with another antenna, like my 148' LoG, though the feedlines for those are across the house. I try to do a comparison at some later time.

[RobRich]

Quickly skimming VLF and lower LW with the active miniwhip, I was able to spot Cutler at 24KHz, Aguada at 40.75KHz, and WWVB at 60KHz.

Rolled by a few beacons in LW. I would say my CW is limited, but it is more like nonexistent without a decoder. Morse code just does not work for me.

NavTex at 518KHz; probably Miami.

[RobRich]

Still running in the background. Been listening to Asian DX on 40m SSB this morning, including currently an op from Papua New Guinea running 100w into whatever loop antenna.

[RobRich]

Now grounded to the top of the mast, too. Did the same thing I did at the bottom of the mast. A couple of F connectors, a female-to-female barrel connector, and a hose clamp. Yeah, it is a mechanical connection, but soldering at the top of a mast with wind blowing (and thunder in the background) did not seem like a fun idea.

Might go back out in a few to add a few snap-on ferrites, though AFAIK, most of the ones I have available currently are for higher frequencies. Whatever, I suppose.

I was also considering adding a few on-ground radials at the bottom of the mast. Like maybe four to eight 9' wires. Still undecided, though.

I will try to deploy the other miniwhip later this week or next, then take a closer look at MW with the phaser inline.

................

Update. A snap-on ferrites added, for whatever they might or might not help. I need to order some more mix 31 or 43 ferrites. I just do not like the price for large ones.

[~SIGINT~]

I was never pleased with my Mini-Whip antennae. One of them works not bad but the other not so well because of its location. They most certainly do not perform like the one at the University of Twente. I'm going to replace one of them with a short vertical of some kind. I just need to design and get around to building it.