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Author Topic: Best MWDX antenna?  (Read 47139 times)

Offline alpard

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Best MWDX antenna?
« on: April 11, 2021, 2133 UTC »
What would be the best MWDX antenna?
I have been using MLA30, and it does work well sometimes when the band condition is good.
But on other nights, it is not great.

Which antenna will work best in MW and HF Low Band DXing?
What are you using for these band DXing?

Thanks
« Last Edit: April 11, 2021, 2212 UTC by alpard »
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Re: Best MWDX antenna?
« Reply #1 on: April 11, 2021, 2318 UTC »
Because of the constantly varying propagation conditions I would say that there is not any one type of antenna that is better over the other.  There are multiple factors involved, horizontal or vertical polarization and skip vs. ground waves to name a few. MW stations in the 500 to 1,600 kHz band transmit vertically polarized hence the telescopic whip antenna on most AM radios. Those AM stations actually do not have any transmitting antennae per say. The tower(s) is/are the antennae. Next to having a whip, an antenna which exhibits good horizontal and vertical characteristics is the best of both worlds. This can be highly dependent on how the antenna is installed, I.E. horizontal, inverted-V, sloper etc ...

I currently use 4 x HF antennae in a fixed installation. A Barker & Williamson installed in an inverted-V fashion, a horizontal end-fed long-wire antenna which is relatively low to the ground (about 12 feet), a Wellbrook loop and a cheap clone of a miniWhip antenna. My primary antenna is the B&W with the end-fed second. As propagation changes I also change antenna. I sometimes will start to loose contact on the B&W and switch to the end-fed and the signal is back. The end-fed is also electrically quieter (less static). I primarily use the loop on beacons, down to about 20 kHz. I also use it on HF when I want to null out interference.

For portable use, I have a random length wire dipole and an AirSpy YouLoop antenna.

This summer's experiment will be an L antenna. It has the best of both worlds (horizontal and vertical).

Start with an end-fed coupled to a proper un-un matching transformer. Insert an A/B switch and you can then flip back and forth between the end-fed and the MLA loop. They both have unique characteristics.

Here is part of my antenna farm. DC to 2 GHz.

« Last Edit: April 12, 2021, 0041 UTC by ~SIGINT~ »

Offline alpard

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Re: Best MWDX antenna?
« Reply #2 on: April 12, 2021, 0849 UTC »
Quite agree - the propagation keeps changing, so having many different type of antennas are great advantage.   Antennas are the most important factor in RXing. Even the best receivers will perform poorly with inefficient antennas.

Will try to set up End Fed wire antenna based on your recommendation.  Thanks.

And I am also thinking of a vertical antenna, EWE and Flag antennas too.  But vertical being omni directional, I was wondering if it will be hearing several different signals on one frequency most of the time which makes readability suffer.

EWE and Flag seem getting good reviews for MW DXing, but they are directional nulling one directions which will miss DX signals from the Nulled direction, and it is not rotatable.

Your Wellbrook looks great and I bet it works very well too especially with the rotator?  What is the white pole between the Wellbrook and B&W?
I notice you have 2x Mini Whips, one on the pole, and the other under what looks like Air Conditioner box?

Great set up on the antennas. Compliments!! Your balcony looks ideal for the antennas.
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Offline ChrisSmolinski

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Re: Best MWDX antenna?
« Reply #3 on: April 12, 2021, 1044 UTC »
EWE and Flag seem getting good reviews for MW DXing, but they are directional nulling one directions which will miss DX signals from the Nulled direction, and it is not rotatable.

This is a feature, not a bug  :)

While I agree there is no single "best" antenna for MW (or any other type of) DX, one characteristic they share is that they are directional. You want to limit reception to a particular direction, both to reject stations as well a reduce noise/static pickup from other directions. It's all about maximizing signal to noise ratio. This means that you either need to be able to rotate it (such as with a small loop, by small here I include loops up to 10 ft or so on a side, anything that you can still stick on a rotor and rotate) or have multiple fixed directional antennas (Beverage, D-KAZ, etc) each aimed in different directions. I use the latter method. 
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Offline alpard

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Re: Best MWDX antenna?
« Reply #4 on: April 12, 2021, 1359 UTC »
Sure. It is also problem that the direction  I want to NULL incoming signal is wide open, but where I want more signals received, there is a building blocking :)
So, it had been very tricky to find the best position of FLAG or KAZ or EWE in this property, if I were to installing one.

So, I set up 2x MLA30 one facing EW and the other NS directions.
And I have a Wellbrook Loop pointing to SE and NW.
They can be selected by the menu of the RSPdx, which allows you to install 3x antennas at once, and
change in the menu by clicking ABC.

But I have been feeling these antennas are still not good enough for RXing the trans Atlantic MW stations or
Far Eastern MW stations.  Maybe MW DXing condition is poor recently?
Or do I need better receiver? I wasn't sure.  But I was more inclined to be suspicious on the antennas, and
their DX signal hearing capabilities.  Perhaps I need larger and more concentrated directional antennas?

I can hear pan European signal quite well over night recently with the antennas I have, but for trans Atlantic or Far Eastern
signals or from South America or Pacific, I have not heard any for ages.
« Last Edit: April 12, 2021, 1421 UTC by alpard »
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Offline ThaDood

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Re: Best MWDX antenna?
« Reply #5 on: April 12, 2021, 2055 UTC »
I've made one of those gods-eye antenas for MW, with a variable air CAP, and done well both indoors and out. They are, however, very bi-directional. http://167.250.5.172/docs/Radio/Antennas/Am_Loop_Antennas_2004.pdf
The other thing that can be done is to make an inductive loop coupler to the End Fed Longwire. Me??? I still want to lay down the W.O.G., (Wire On Ground.), since that's suppose to be excellent in noise reduction. Hopefully, this Fall 2021, that will happen.
I was asked, yet another weird question, of how I would like to be buried, when I finally bite the big one. The answer was actually pretty easy. Face-down, like a certain historical figure in the late 1980's, (I will not mention who, but some of you will get it, and that's enough.) Why??? It would be a burial that will satisfy everyone: (1) My enemies will say that it will show me where to go. (2) On the same point, I can have my enemies kiss my butt. (3) It will temporarily give someone a place to park a bicycle. See??? A WIN / WIN for everyone.

Offline alpard

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Re: Best MWDX antenna?
« Reply #6 on: April 12, 2021, 2223 UTC »
I've made one of those gods-eye antenas for MW, with a variable air CAP, and done well both indoors and out. They are, however, very bi-directional. http://167.250.5.172/docs/Radio/Antennas/Am_Loop_Antennas_2004.pdf
The other thing that can be done is to make an inductive loop coupler to the End Fed Longwire. Me??? I still want to lay down the W.O.G., (Wire On Ground.), since that's suppose to be excellent in noise reduction. Hopefully, this Fall 2021, that will happen.

Wow.  Fantastic info on the Loop Antennas. 
I was thinking of making one of those actually.
But always under impression indoor antennas will not be
as good as anything outdoor one. Maybe it is not always the case.
Thanks for the link for the document.

Please let us know about  your W.O.G. project.
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Offline ~SIGINT~

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Re: Best MWDX antenna?
« Reply #7 on: April 13, 2021, 0013 UTC »
The white pole between the loop and the Barker & Williamson (B&W) is one of the end pieces from the B&W. If you follow the wire up you will see the centre support and as you keep going toward the house another support before it goes to the balun. I'm standing about 50+ feet back from the house which distorts the picture. The B&W is like a T2FD and is setup as an inverted-V. That is somewhat around 160 feet or so of wire between both legs.

Mini-Whips, yes, you are correct. The second one is hanging from under the air conditioner and feeds my Icom IC-R75. It's my bedroom night stand radio. I'm not overly pleased with the mini-whips. They are not the original design. They are ok but the two that I have are not great performers, at least not what I expected out of them. I don't have a real PA0RDT Mini-Whip to compare them to.

I am very pleased with the Wellbrook. It is on a HAM-IV rotator, which is an overkill, but that is all I had handy at the time and I like the controller. I unfortunately do get killed by local AM stations so as a test I ordered some Nooelec Flamingo band stop filters. They just came in this afternoon so now I have something to play with. I did not want to entirely kill the AM band as I wanted to do some AM DXing with the loop but the loop has so much gain that it overloads the receiver front end and splatters. I have been operating it with a 10dB attenuator. If the Flamingos work I can then build individual notch filters and only remove the offending stations from the AM band as opposed to the entire band.



I would not worry to much about that building in your way. By design, AM broadcast station signals are engineered to travel by groundwave. Keep the antenna low to the ground.

Since you have E/W & N/S antennae, have you thought of putting one of them 180 degrees out of phase? If you want to listen to E/W you put the N/S antenna 180 degrees out of phase to null out the interference from that direction. Same principle as putting audio cables out of phase. Chris who is on this thread manufactures and sells BALUNs. Maybe he can manufacture a transformer that is 180 degrees out of phase. Now I know I just got Chris's gerbils turning because he could actually do that with his antennae as well.

I have one more antenna on the way, the new version of the RTL-SDR L Band Patch for GPS, INMARSAT and IRIDIUM. Now it is time for me to go and catch some radio waves.
« Last Edit: April 13, 2021, 0016 UTC by ~SIGINT~ »

Offline alpard

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Re: Best MWDX antenna?
« Reply #8 on: April 13, 2021, 0929 UTC »
I see what you mean.  The camera lens can distort the realities I suppose. :)  It looked  like another vertical antenna of some sort :D

I also have a R75, and it is a great radio. It works very well with my Wellbrook.  I also had some problem with the Wellbrook.  It was very very noisy. The problem was cured by inserting a few ferrite ring choke filters to the incoming antenna coax and also the power supply lead. It now works very nicely without any noise.  On my RSPdx it can be seen well balanced and very sensitive. 

It is very directional, it won't receive  the signals which is not coming from where it is pointing, hence rotator is a must if one is using one antenna like this.  But I cannot use rotator - so instead I set up different loops pointing different directions.

I was thinking about phasing the 2x loops. I have this T piece BNC, and  thought it can be inserted with 2x coaxial cables from the 2x loop antennas.  But I was not sure exactly how they work.  I was under impression you need a phasing controller. Some people were using the MFJ noise canceller, and there are now a cheap Noise Canceller which look like a clone of the MFJ on eBay for about 50 bux.  Not sure how good they are. But yeah, I would be interested to know the Balun manufactured by Chris, how it works. I am glad you mentioned that, because it will definitely increase MWDX capabilities with 2 or 3 loops I have.

I can see your trouble with the nearby AM stations causing splatter. I too have the similar problem. I have this AM relay transmitter about 5 miles west of my house.  Due to that, if I point any antenna to the direction, it just gets overloading from the AM signals.  :(  So, my DXing on anything coming from west is limited.
The only way to resolve the problem is either I move house to somewhere else, or waiting for shutting down the transmitter for good. A lot of AM transmitters get shut down recently either their going for DRM or for other reasons, so ... hope is still there.  Failing that we will move to somewhere else countryside peace and quiet and ideally near the sea :D

Yup, the most important thing is, to listen to the bands and getting the DX. Time is short. I stopped most of other radio activities such as ham radio, DIY home brewing etc. Because SWLing alone is enough taking most of my spare time. I will get back to Ham Radio, when I am retired and settled with plenty of time then :)
« Last Edit: April 13, 2021, 0954 UTC by alpard »
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Offline ChrisSmolinski

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Re: Best MWDX antenna?
« Reply #9 on: April 13, 2021, 1034 UTC »
Phasing two antennas involves mixing the signals while adjusting both the relative phase of the incoming RF as well as the amplitude, so you can get cancellation of an offending station/signal. So it is a bit more involved than using a T adapter.

There are hardware phasers (MFJ-1026 for example), and you can also do it in software if you have an SDR with two RF inputs (SDRPlay RSPduo and SDRuno, AFE822x and SdrDx for two examples).

If you can come up with a way to creatively use a rotor, that might be the best solution.

If you cured the noise/RFI issues with your Wellbrook by using ferrite chokes on the coax and power cables, most likely the issue was common mode pickup on the cables, not the offending signals getting picked up by the antenna itself, as chokes don't remove that.
« Last Edit: April 14, 2021, 1026 UTC by ChrisSmolinski »
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Offline RobRich

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Re: Best MWDX antenna?
« Reply #10 on: April 13, 2021, 2106 UTC »
After looking at the minimal components inside the affordable eBay phasing units, I would suggest probably opting for something a little more developed at the cost of a few more dollars.

Interesting timing with the discussion, too. I have a phasing unit currently on order with igor_us4lg via eBay. His models are $73 to $77 USD shipped depending upon the casing, knobs, etc. Shipping could take awhile because of him being in the Ukraine, but the delay is likely no worse than many of the China-based electronics sellers these days.

https://www.ebay.com/usr/igor_us4lg

Big pluses for me? His boards look well built, his posted schematics appear reasonable IMO, and he has 100% positive feedback with hundreds of transactions.

Update.... one particular note to add. Most of the off-the-shelf phasing units on the market are designed for HF frequencies. There are mods to extend mediumwave capabilities, but be prepared to remove and change components. For example, W8JI has info on modifying the MFJ-1025/1026 phasing unit to bypass the ~1.9MHz highpass filter and decrease the lower frequency limit.

https://www.w8ji.com/mfj-1025_1026.htm
« Last Edit: April 13, 2021, 2115 UTC by RobRich »
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Re: Best MWDX antenna?
« Reply #11 on: April 14, 2021, 0108 UTC »
Unfortunately, I believe that ferrite are now part of the hobby. I use them as well along with some special AC line filtering. I have the ferrites installed at the cable entrance to the house. I found that walls are noisy. I might put some additional ones at the antennae this summer, but chokes at the antenna input are not so critical unless the antenna is the victim, I.E. noise is travelling up the coax toward the antenna and the antenna is picking up or worst, transmitting the noise. Chokes at the antenna are more common when transmitting or if there is some down-converter or amplifier at the antenna being fed by a noisy switching power supply. I had this problem with the mini-whip antenna. It was the source and my other antennae were the victims. Needless to say, no dirty switching power supplies in my installation. They are all replaced with old fashion analogue power supplies with good filters.

At the receiver input, I have a common mode noise filter. I managed to squeeze 10 turns of coax on a ferrite core. After several months of stock shortages, Palomar Engineers is finally shipping some of their products that were previously hard to obtain. I have been wanting to replace the VALCOM ATU that you see in the previous picture. It is a broadband (receiving) matching transformer, 100 kHz to 30 MHz. It is designed for a 35 foot vertical whip antenna. It will be replaced by a Palomar Engineers Bullet 50:450 (9:1) VLF HF UNUN (20 kHz to 30 MHz). I have 2 of them in transit. One for the end-fed antenna and a spare to play with. I can also transmit in the bullet. The VALCOM ATU is good, but it is in a water proof aluminum enclosure and is very heavy. It needs to be mounted, not hanging from the guy wire like I have it installed. All this to say that I also have a Palomar Engineers common mode noise filter coming in the shipment. The home brew will move over to the Icom.

Don't forget the other sources of EMI in your house such as cable / satellite TV boxes and believe it or not, ADSL/VDSL modems can be incredibly noisy. It took me a long time to hunt that one down. My Icom had a constant shhhhhhhh noise in the background. I went around with a special EMI test antenna and receiver to find that one. I unplugged the unused telephone line in the room and the noise went away. I don't get that one. I tested the phone line, inserted an ADSL filter, plugged in a phone to terminate the line and I just couldn't get ride of the noise. It's a strange one. Some day I will get back into it.

Now, time to update everyone on my new Flamingo AM broadcast band notch filter. So far so good. First impression is that the filter works very well. I will take it to the bench on the weekend and sweep it to see if it meets the specified specifications. Even with the filter, (>40dB typical, 350 kHz and 1900 kHz) there is still plenty of AM signal left from the Wellbrook for some good DXing. Below you can see 1540 kHz splattering all the way above 5 MHz and up. The second screen shot is with the filter inserted at the receiver input. Looks good. The 3rd screen shot is a slice of the AM band, still lots of signal there to play with. I wanted to grab a screen shot of 1540 kHz but they switch to low / night time power at 00:00 UTC and I just missed it.



Offline RobRich

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Re: Best MWDX antenna?
« Reply #12 on: April 14, 2021, 0245 UTC »
I have various ferrites on feedlines, powerlines, etc. I also have KD9SV common-mode chokes back near the receivers for a couple of my better antennas. KD9SV rates them for 3000 ohms of resistance at lower HF frequencies, so I suspect probably mix 31 or maybe even 73/75 ferrites underneath the potting material.

I have UPSs with power filtering on several electronics, though the radios typically get automatic voltage regulators with line filtering instead, as I am not too concerned about power backup for them. I like and use the APC Line-R series, though the 600VA baseline model starts around $50 new these days.

Otherwise, you can find used good condition ESP XG-PCS-15D and similar office copier-grade line protection models with filtering for around $20 to $25 shipped on eBay.

About the modem, check the power supply, especially if it is a wall wart. It could be a switching PSU with little to no regulation and filtering, though I have seen even linear supplies with similar issues as well.  ​A few turns of the power cord on a common mix 31 or 43 ferrite might help.

----------------

BTW, while on the topic, Chris here at HFU offers a couple of interesting matching transformers as well. :)

https://www.blackcatsystems.com/rf-products/potted_matching-transformer-unun-balun-beverage-longwire-k9ay-flag-ewe-dipole-antenna-shortwave-ham-radio.html
https://www.blackcatsystems.com/rf-products/cyclops_rf_ham_shortwave_radio_matching_transformer.html
« Last Edit: October 04, 2021, 2054 UTC by RobRich »
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Offline alpard

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Re: Best MWDX antenna?
« Reply #13 on: April 14, 2021, 1552 UTC »
Yup, Phasing 2x Loops can really increase MW DXing capabilities I thought.   MFJ 1026 seems way too over priced for what it is.  QRM eliminators on eBay from China seem going for about 40 - 60 Euros.  But recently they started adding taxes after you click on Buy It Now, and then you find the total is far more than what was showing as the price.  Not good.  I was hit by this new system on eBay, and stopped buying anything from overseas sellers.

But the Russian made units seem good, as you say price seem higher, but if they are made of better parts and work better, then maybe worth it?

I think my Wellbrook Loop has a poor quality PSU.  The loop is older type which gets fed with -12V in the centre, so it will not accept any PSUs, hence I am kinda stuck with the PSU.  It seems the PSU was either generating high noise or was picking up the common mode RFI.  As I said a bunch of small ferrite filters on the leads seems to have cured the noise.

I too bought a few packs of the ferrite filters, and was regretting having bought too much of  them, but before soon, they all ran out. I will need more of them.:(

It is strange my other active loops MLA30 don't seem to have this noise problems, but they are just noisy on certain bands.

There seem plenty of ideas for good MWDX antennas.  Flag and phasing the loops seem definitely good idea, and there is recommendations for Beverage, but it requires large piece of land space of at least 100m I gather.  My back garden is only about 20 x 20m max.  But what I feel is that you don't need large antennas, because they might also be picking up more noise?
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Offline ChrisSmolinski

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Re: Best MWDX antenna?
« Reply #14 on: April 14, 2021, 1600 UTC »
I think my Wellbrook Loop has a poor quality PSU.  The loop is older type which gets fed with -12V in the centre, so it will not accept any PSUs, hence I am kinda stuck with the PSU.  It seems the PSU was either generating high noise or was picking up the common mode RFI.  As I said a bunch of small ferrite filters on the leads seems to have cured the noise.

If you cannot find a -12V linear DC supply locally (they do exist), you could take a +12V linear DC supply and swap the wires to provide the necessary -12V output.

But what I feel is that you don't need large antennas, because they might also be picking up more noise?

If you live in a RFI filled urban environment, you may not get much benefit from a large antenna. But in a rural environment, you most likely would. I certainly do  ;D
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