YouLoop performance?
Has anyone using YouLoop with KiwiSDR? I am wondering if it performances well. All the article I saw about YouLoop is with Airspy and says need high dynamitic range in the receiver. Not sure if KiwiSDR is considered high dynamitic range.
Comments
Please post a link to the article
The Youloop by itself is not suitable for use with a KiWi SDR, as it does not have sufficient gain.
You could add a 20dB pre-amplifier, but to be honest IMHO the Youloop is a good example of marketing hype rather than sound technical performance.
In my experience, a normal single turn loop generally performs better.
The LZ1AQ circuit is difficult to beat for the price and minimal complexity.
There is much more information in other sections on my website.
Regards,
Martin
This is the article The Airspy Youloop is a freaking brilliant passive loop antenna | The SWLing Post
So, If I am reading your diagram correctly, this loop consists of 2 coax. At the top where two coax meets. The shield of one coax connect to the center conductor of another coax. Both coax connect to one side of 1:1 transformer at the feed point and the other side of transformer connect to feed line center conductor and I am not sure where is the feed line's shield connects to.
This looks to me almost identical to YouLoop's design?
For LNA pre-amp, is there any recommendation?
Yes, the diagram is direct from Airspy who market the Youloop.
Note that the SWLing post article concentrates on MW reception and not the 0-30MHz spectrum as a whole, which the KiWi sdr covers. The blogger also initially connected his Youloop version incorrectly, and he is basically apologising for his own mistake, which doesn't really inspire confidence in he rest of the post. The comments are pretty poor too.
Unlike most passive broadband loops the Youloop requires a preamp with a high input impedance in order to cope with some of the 'unusual' features of the design.
These 'features' are IMHO problematic, and the requirement for a preamp with a high input impedance flags up all sorts of issues with me.
The topic was discussed on the Airspy forum some time ago and I'm not aware of any further updates.
This was the circuit proposed in the discussion.
In the UK we have an old saying "you can't make a silk purse out of a sow's ear"
Bottom line don't bother with the Youloop, you will spend so much effort and money trying to make it work well enough, that you may as well chose something better as a starting point.
I have tried and tested a lot of compact / active antennas and I'd strongly suggest that you take a look a the LZ1AQ circuit or ready made unit, if you want something that will work well with the KiWi sdr.
Or if you want a slightly cheaper ready made design.
Regards,
Martin
I'll echo the recommendation for the LZ1AQ amp. I have a 2m x 2m crossed parallel loop feeding one, and am very happy with the performance given the very small dimensions. I have full sized antennas I use most of the time, but the directionality of this antenna is very useful on the LW & MW bands.
The one from Cross Country Wireless looks very similar to MLA30?
The Cross Country Wireless loop amplifier is very different to the poor quality MLA30 which uses a video amplifier chip.
Another design similar to the Cross Country Wireless is the German Blue Wave
https://www.heinzstampfl.ch/en/produkt/blue-wave-active-antenna-0-05-30mhz/
Both are single ended designs with a common base transistor followed by a buffer stage, a bit like splitting a an LZ1AQ, which is a balanced push pull amplifier, down the middle.
The advantage of a balanced push pull amplifier is that it provides better performance in the presence of strong signals.
Regards,
Martin
Blue Wave seem nice. Is there any know supplier of similar design in North America? So that I don't have to wait for a few months :)
What is your budget and are you able to build circuitry etc.?
@WA2ZKD <200 and prefer off the shelves for circuitry. But if instructions are easy to follow (e.g. TARPN's TNC2), I am open to trying it out.
Contact Everett Sharp N4CY.
He hangs out on the Loop Antennas IO group, and usually has a selection of bare PCB's and ready built loop amplifier boards that he can make available.
https://groups.io/g/loopantennas
Regards,
Martin
Got the N4CY loop up and running. Works pretty well. Currently, it's only 5ft off the ground. Does the height affect performance?
The loop height doesn't matter too much, once it is clear of 'ground clutter' increasing the height brings diminishing returns. 5 or 6ft above the ground is probably OK, but it's more important to place it in an electrically 'quiet' location and to rotate it for the best rejection of unwanted noise, than worry about the height it's mounted at.
Regards,
Martin
"Ground Clutter" do you mean it has to be taller than buildings?
No. Probably no more than a few loop diameters is enough to get into a slowly varying region. From my measurements at MW, moving up 10-20m probably helps SNR slightly but not grossly.
@n6gn So you mean 2 - 3 loop diameters above ground?
I tried a You Loop with my SDRPlay Duo rather than the Kiwi.
It seemed to work reasonably ok on 2m and 70 cm but virtually nothing heard on any of the HF bands and has now been consigned to the jumk pile
The Youloop only really works with Airspy products, as they have a very low noise figure and good resultant sensitivity (although it should be OK with the SDR Play, as long as you fully engage the pre-amp). This effectively makes the Youloop / Airspy combo work in a similar manner to an active loop antenna.
My personal view is that Moebius loops,such as the Youloop, are an unnecessary complication, and are merely a marketing term, that has been used to try and infer some sort of technical advantage (and sales 'feature' ) over much simpler designs.
Read about my experiments here.
Regards,
Martin
If cost is the concern, I've had good results with this loop amplifier: https://casarain.com/products/lamb-1b-hf-receiving-loop-amplifier
It's only $20 but of course you still need an enclosure for it to keep it dry. For the loop itself, I used 1-inch PVC as a frame to hold the copper tube (you can use coax too). Picture below.
I've gotten pretty decent results with this loop, especially on higher frequencies (20m and up).
I have modified my LAMB-1 amplifier board to work with balanced feedline. I'm using outdoor rated CAT-5 as my feedline. One pair for the signal, one for DC voltage. The LAMB-1 is intended to be used with unbalanced feedline (coax) and a DC power injector which can be very inexpensive to buy or build (really just an inductor and a cap).
That said, the LZ1AQ solution is pretty great and if I was going to make another one that's probably what I would do!
Cheers,
Nick
Hi Nick,
The LAMB-1 is basically another copy of a design by M0AYF
which is turn was based on the original design by John, G8CQX
It's a moderate performer and is certainly better than the Chinese MLA-30. But it does have rather a high value of input impedance, which means that it favours the HF bands rather than frequencies lower than 1MHz.
As you have already said, it is out performed by the LZ1AQ and Wellbrook designs, which having tried many types of active antenna, I'd say are the 'gold' standard to aim for.
This antenna design is basically the LZ1AQ, but with some interesting additional features that may appeal to some folks.
https://elekitsorparts.com/product/portable-active-loop-antenna-loop-antennas-for-sdr-shielded-loop-mobius-loop-youloop-preamp
Note that although it claims to be suited for use with the Youloop and would probably work, the LZ1AQ design works better with a low inductance loop.
If you are at all interested in using, buying or building a broadband loop antenna for receive purposes, then I would highly recommend joining the Loop antennas IO group. Which contains plenty of technical information, guidance and test results.
If you wish to further understand the parameters that make a good loop antenna design, take a look at a couple of my other pages on the subject.
Regards,
Martin
Wow, Martin. Thanks for all of the great insights and advice!
You've clearly done your homework! You've got me thinking about possibly modifying mine (or making a new one). I'm not using mine on the kiwi though, I'm using it as an RX2 on my HF rig. So it kind of does double duty depending on what I need: Lower noise rx (great for lightning static) or a noise antenna to null out undesired signals/noise when combined with the main antenna (a huge 200m horizontal loop).
It suits my needs pretty well, but it would be fun to experiment further. I think my interest is mainly 1MHz to 14MHz. Any suggestions you have would be welcome. Right now it's about 1m diameter and constructed of 1/4" copper tubing. I could easily adapt my frame to use LMR400 with or without a crossover at the top. Then of course is the amplifier...I have the CAT5 run and I'd much prefer to keep that as the feedline.
Regards,
Nick