Weekend YouLoop Experiment

[JustGreg]

I have been looking at various small antennas.  Soon to be 72, I know a change will come in the future that will not allow me to have an outside wire antenna.

I have looked at the MLA-30, which is Okay if one wants to listen to shortwave broadcasters.  I tried the "mini-whip", which is an excellent antenna for listening to electronic noise.  When I got my AirSpy HF + Discovery, I also got the YouLoop. 

Using the YouLoop even with the HF + Discovery, it was clear that a preamplifier was needed.  I tried several ideas such as increasing the loop size.  The larger loop size was a help but a preamplifier was needed.  Going through my radio  stuff, I did not find a preamplifier that did the trick.

For another other idea, I purchase Nooelec LaNA preamplifier.  Another idea bit the dust.  This week stuck in the house due to the cold weather and COVID, I decided to try the YouLoop and the Nooelec LaNA preamplifier.

I was pleasantly surprised to find they were almost as good as my outside wire antenna in limited frequency ranges.  The YouLoop/LaNA work well from about 1 to 4 Mhz and in the FM broadcast band up to about 106 MHz.  I used 2 meter pieces of
cable for the loop elements, which are long and reduced the VHF performance.  The longer cable elements did help in the lower bands. 

The YouLoop/preamplifier in the 1 to 4 MHz range produces signals that are clearer due to less noise pickup and a lower noise floor.  Over the rest of the HF band, the wire is better.  But for listening to shortwave broadcasters, the YouLoop/LaAA is usable up to about 12 MHz. 

It seems to be hit or miss above 12 MHz.  I am not sure what is going on.  I tried using an antenna analyzer to determine the impedance of the YouLoop by itself as function of frequency.  I got inconsistent results, especially above 12 MHz.

I now have a good small antenna for listening in the house.  Below is a picture of the YouLoop and preamplifier on a wooden frame.  The loop dimensions are 48 inches wide by 45 inches high.  I hope this is a help for others.

[~SIGINT~]

Thank you for the wright up on the YouLoop and pre-amp. I had been considering ordering that pre-amp from Nooelec for some time now to compliment my YouLoop but have never gotten around to it. I have both the Nooelec Flamingo AM and FM notch filters and have been pleased with them. Same with the YouLoop.

My method of mounting is far less sophisticated. All I use is a string between the top and lower couplers. This allows me to hang the antenna pretty much anywhere as for example in a window hanging from a curtain rod. The weight (pull) from the feed line keeps things taught and the the string between the couplers keep the loop formed.

[JustGreg]

An "Oh By the Way" on the Nooelec LaNA, there is no noise figure specification for it.  I have attempt to get an ideas of what the value is.  My guess is somewhere between 6 and 10 dB, which is fine for HF work.   I have been doing several different experiments and the wood frame does help.  Yes, my initial use of the YouLoop was hanging it on a wall with some cup hooks into the wall board.

Last night, I used it for Undercover Radio on 1720 K.  The YouLoop/LaNa was better for the station than the wire.

My next step is to try AirSpy preamplifier, with a noise figure specification on .75dB.   It also covers a wider range (50 KHz to 4 GHz).  It should be here by the weekend.  I will post the results after the weekend listening.

[~SIGINT~]

I see that their preamps are manufactured by Uputronics. You can get further data here:
https://store.uputronics.com/index.php

I cannot find this 50 KHz to 4 GHz AirSpy preamp you are referring to.

The only similar product which I can see is one with a frequency range of 100 MHz to 4 GHz which will not cover the HF band. AirSpy has is listed as Wideband 0.1-4 GHz Preamp which in reality is 100 MHz to 4 GHz.

From the AirSpy web site: https://v3.airspy.us/product/upu-fpwb/
From the Uptronics web site: https://store.uputronics.com/index.php?route=product/product&path=59&product_id=102

[JustGreg]

My mistake on frequency range.   I confused the LaNA low end with UpUtronics amplifier.  Oh well, I will try to it see how it works for FM broadcast and NOAA stations after I get it.  Thanks for the information on the data sheet.  I have it.

Just checked the data sheet and it lists 0.1 MHz on the low end.  So this weekend, I will be testing the UpUtronics.  Hopefully, it will be better.  It is almost twice the cost of the Nooelec LaNA.

On Nooelec LaNA, I had to get mine with a case from Amazon.  The Nooelec store does not list the version with the case. 

Thanks for the help ~SIGINT 

~SIGINT was correct.  There was a typographical error on the datasheet.  The low frequency is 100 MHz (0.1 GHz).  I told the manufacture of the error on his datasheet.  Hopefully, it will be corrected.

[RobRich]

If an e-field probe - i.e. an active miniwhip - returned mostly electronic noise, then you are likely testing these antennas in an EMI/RFI-rich location. No preamp is going to help. In fact, most will make it worse, especially with these various untuned small fractional-wavelength antennas.

Getting an antenna even just a few feet outside and/or above your residence can dramatically improve SNR.

[JustGreg]

RobRich, thanks for the information.  I am not using E field sensor (active mini whip).  I am experimenting with the YouLoop, which at MF is small magnetic loop.  I have just completed an EMI source hunt through out the house and have found them (most were small USB chargers or LED lights).   I took the appropriate measures, either replace them with a better low noise charger or make sure they are off or removed from the power when I listen.  The remaining sources are located on other properties. 

Once interesting one is my neighbor's solar panels on their roof.  The DC to AC converters are very noisy in MF/HF region.  The noise is on powerlines and can be heard under them for about a 1/2 mile.   The good news is at my wire antenna location is far enough away so this source is not an issue.

I do agree with an additional preamplifier will not help any of the E-field type antenna, which always seem to pick local noise sources.  This is me trying to get the best performance out of the YouLoop.

[JustGreg]

This has been an interesting experiment over the last two weeks.  Here is what I found out.

The YouLoop with longer elements does work.  But, one needs to have a low noise receiver.  For most HF receivers, one will need
a low noise preamplifier (noise figure < 2 dB).

I found the YouLoop with a preamplifier was best from 1 to about 4 or 5 MHz   It was OK for general purpose broadcast listening from 5 to 15 MHz  This is not the antenna for weak HF signals.  The aperture area of the YouLoop is not that large and limits performance.  It is a small magnetic loop.

I did find the YouLoop with a preamplifier was better for medium wave AM broadcasts than my wire antenna. It works OK in the VHF FM broadcast band.  For FM broadcast stations, it is about equal to a 29 inch whip or commercial
folded dipole.

I tried the Nooelec LaNA and generic Chinese one.  Both use  a RFIC  gain device and have similar performance.  I found powering the Nooelec LaNA through its USB port by a USB charger.  The USB charger introduced broadband noise into the LaNA and reduced its performance.  The Nooelec LaNA also needs a DC block on its output when powered through the USB port.  The generic Chinese one with a 12 volt "wall wart" does the job.

For its price, the YouLoop is worth it.  Yes, you need to add a preamplifier, but you can get a decent one for less than 50 dollars.  The total cost is close to that of MLA-30 loop and one gets better performance in my humble opinion.  Yes, both loops have limited HF performance.  I will keep my YouLoop combination and connect it to my Malachite DSP SDR for listening to the AM and FM broadcast stations.

Who knows, maybe the weather will give me a brief power outage and I can find out how it works in a lower noise environment.

[RobRich]

I was going by the comment: "I tried the "mini-whip", which is an excellent antenna for listening to electronic noise."

I use active miniwhips, but they are away from the house and RF grounded.


I have used the YouLoop with an antenna tuner to improve the match with a portable receiver, thus improving the usable signal transfer enough to not need a preamp. Also the tuned circuit can serve as a passive preselector.

https://www.hfunderground.com/board/index.php/topic,71326.msg241978.html#msg241978

[JustGreg]

Thanks RobRich for the information.  Yes, I agree with using an antenna tuner or matching device with the YouLoop.  I tried my MFJ Versa Tuner (MFJ-941D) with YouLoop.  I found I could not match to the YouLoop.  One frequency, I did get a match to 2.5 to 1.  It was CHU on 3330 KHz.  The signal of CHU was improved a bit.  I found the noise floor dropped and signal increased.  It was an improvement, but not as great as I hoped.  I see you used a simple LC tuner.   Good idea, simpler things sometimes work better. 

Your antenna measurements are similar to what I found with my antenna analyzer.