MLA-30 antenna - IZØKBA Lorenzo

HF Active Loop Antenna

At the end of 2019 I started seeing videos and articles on various YouTube channels and Facebook groups on an active loop antenna called MLA-30, in which it was described as an excellent device for receiving shortwave at an interesting price: it is possible find it on Amazon around 40€ shipped from China, it arrives after a week or so.

It is a Chinese product, it seems to closely resemble the Bonito megaloop FX o ML200 , it is composed of an iron wire that forms the ring with a diameter of about 90 cm connected with butterfly screws to a watertight box containing the active components that they amplify the received signal, in particular an LMH6550 operational amplifier from Texas Instruments is used, resin-coated both to protect them from humidity and salt, and perhaps to avoid various spotting. An RG174 cable with an SMA connector comes out of a small hole. The cable coming from the antenna must be connected to another box (biasing) which has the task of supplying it with current, it is powered by a USB cable; then there is the exit to the receiver. This box isolates the voltage coming from the USB towards the receiver, sending it only towards the loop; there is also a trimmer with the word ATT, an attenuator therefore. All of this is provided at the time of purchase and also appears to be of good quality.

The antenna allows you to receive in the frequency range between 100kHz and 30MHz.
There is no documentation provided and \ or on the web. However, it should obviously be installed far from obstacles on a plastic support pole, not supplied; however, it can be dismantled and transported easily for use outside the home. All connections and cables are with SMA connectors, making it ideal for SDR receiver. A clearly visible green LED on the power supply box indicates that the antenna is working.
The vertical support element of the loop must be made with non-conductive matrix, a piece of PVC conduit from electrical systems for indoor or temporary installations is fine, if you install it on the roof I recommend the use of PVC pipes for plumbing which are more wind resistant and can better hold the whole antenna

On the various sites that offer it for sale, the graph of an ideal tuned loop antenna is shown, whose radiation lobe is directional, which is certainly true with tuned loops, but in my opinion it is not very real in such loops. In fact, during my tests I noticed a minimum directivity, how you put it on, receive the stations with the same signal intensity.
By placing the antenna in a horizontal axis, the signals are attenuated.

How’s the MLA30 is?

All compared with a random wire of about 15 meters and \ or with a stylus antenna:

The first thing I noticed is the noise it generates itself, or rather its Biasing Tee, I will talk about it in the next paragraph …

Then, notice that it is a little deaf already above 10MHz, it receives slightly above 20MHz. Local QSOs in CB and in the 10M band are received more or less as with the antenna I usually use.
Conversely below 2MHz it seems to have a fairly good and silent reception. For the bands of 40 and 80 meters it performs well, the wheels of the national QSOs are well received, I was able to listen to US stations in these bands during the first period of use. Keep in mind that at the time of writing we are in a minimum phase of the solar cycle, therefore poor propagation.

In addition, having connected it to a multiband receiver IC-R20, I unintentionally activated the scan and with surprise the repeater of zone were received full scale. If you are interested in listening with SDR or with scanner receivers, you can also do some VHF listening; while scanning i noticed that one parish local radio arrived in an excellent way and full scale, with the original antenna instead nothing.

A feature that struck me positively is that it does not generate cross modulations, that is, it does not happen to listen to “second harmonic” stations at twice the carrier frequency. If this should happen, it is still possible to act on the attenuation trimmer in the biasing box.

Would I buy this antenna again? Yes. Would you recommend the purchase to others? Yes, as long as you install it outside and away from obstacles. It should not be compared to antennas for radio amateur transceivers. The price performance ratio? Considering what it costs, I would say that the price / performance ratio is excellent, but do not expect miraculous receptions.

In conclusion it is an antenna that is worth having, for the cost and for the performances. It is not an antenna for radio amateurs or rather to receive small distant signals, but rather for BCL and SWL that receive broadcast stations or utilities that transmit with remarkable powers.

I think it is an antenna that, apart from a car, would be a FIAT Panda, simple but in some conditions it wins, look for example at the low price and the qualities of the Panda 4×4.
It is a project on which one can indulge oneself in developing modifications to improve it.

What I do not like?

I noticed is that in the biasing box there is a DC booster, which raises the voltage of 5V input from the USB socket, to 12V to power the antenna; to do this, a switching in the integrated circuit must oscillate, when it oscillates it generates noise, and this is not that much appreciated by the receivers. I have read, they have asked me, I have seen, of people trying to try to power it with power banks, batteries, etc. The problem is solved simply by feeding the antenna directly to 12V with the serious and filtered power supplies, probably this choice was made to be able to easily power it during activities outside the home, hotels, campsites, beaches, etc.
It is easy to build 12V biasing cards, just filter the direct current towards the receiver with a small capacitor. It is also possible to use the mini-whip power supply board, applying the 12V supplied by a good power supply, a problem almost solved.

It is also possible to power the MLA30 through the bias provided by receivers, such as SDRplay, on the box of the active element it is indicated that the operating voltage is from 4 to 14V.

Another modification for the MLA30 lies in the addition of a termination resistance of a few hundred Ohms scarce, it serves to make it a little more linear, it is very sensitive around 7MHz, making it probable the appearance of image frequencies of the broadcasting stations in band 41Mt.