Tag Archives: Mag Loop Antennas

The AAA-1C: An affordable loop antenna amplifier kit

I recently stumbled upon the Active Antenna Amplifier (model AAA-1C) by LZ1AQ. At 87.00 EUR, it’s a pretty affordable and flexible solution for those who would like to design or use a loop antenna.

According to the website, it packs a lot of features:

4 remotely switched modes (Loop A, Loop B, crossed parallel loops A&B and dipole)
Each mode can be switched immediately
Good sensitivity and a flat frequency response
High dynamic range
Protected input from strong signals
High immunity to local noise with balanced amplifiers and balanced feed line
Balun transformer coupling for common mode noise reduction
Extensive documentation manuals with detailed description how to build your own small antennas

The amplifier is described as a kit because you must mount the board, wire up the antenna and set up remote switching yourself. It appears the SMT board comes pre-populated, though so I’m not sure if any actually soldering is required (perhaps someone can verify).

AAA-1C kit components

Click here to download the mounting instructions (PDF).

I’m tempted to purchase one this winter for use on mediumwave.

Click here for more info about the AAA-1C at LZ1AQ’s website.

Have any SWLing Post readers built and used this amplifier? Please comment!

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Guest Post: Building a magnetic loop antenna & broadband amplifier for your SDR

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Many thanks to SWLing Post contributor, Dave Gahimer (K9ZCE) for the following guest post:

Small Magnetic Loop Antenna with Broadband Amplifier for SDR Reception

by Dave Gahimer (K9ZCE)

Those with limited space, or antenna restrictions, might find a small 1 meter loop antenna a solution.

My son lives in an apartment. One Loop leaning against a wall gives him acceptable reception with the SDRPlay RSP on the ground floor–2nd or 3rd level flats should have very good reception.

Ten meters off the ground outside should give reception equal to any SWL antenna. We all with SDRs fight the image problem. Normal resonate ham band antennas show too strong reception of unwanted bands/stations. Did I mention noise? Loops are well known for –6 db noise reduction.

Then there is the possibility of SDR chip damage from your 1.5 KW station! In researching Loops we came across LZ1AQ. A Brilliant design /engineer (http://www.lz1aq.signacor.com/). Deep reading sometimes, but a great understanding of what makes a good receiving loop antenna.

Those who chase DX know that sometimes fading is caused by the signals’ polarization changing in the Ionosphere. Having both vertical and horizontal loops, and the ability to combine both signals diminishes this fading problem. Being able to filter the powerful, commercial FM transmitters diminishes image problems. Clipping strong signals at the antenna from very near powerful antennas/transmitters could save the SDR receiver from damage.

The LZ1AQ broad band Amp solves all these problems. http://active-antenna.eu/amplifier-kit/.

My son Ted and I built three, one meter loops from soft ½ inch copper plumbing tubing. One for his apartment, two for my crossed loops antenna. We weather proofed the Copper from corrosion by coating with outdoor clear spar varnish. We shaped the circle by drawing the tubing around a round glass top patio table.

The soft copper loop in held by white PCV plastic plumbing pipe. 1” or 1.25 inch schedule 40. Be careful to check that the PVC is schedule 40, thick wall. The thin wall pipe is not strong in the wind and will crack when you try to drill it.

Drill up to a 3/8 hole for the ½” copper tube to go through, then file out to fit. Here are some photos (click to enlarge):

Check out these links (all courtesy of LZ1AQ) to acquaint yourself with the loop construction and amplifier installation:

http://active-antenna.eu/tech-docs/2_ActiveAA_Mount_20.pdf

http://active-antenna.eu/tech-docs/1_ActiveAA_DandS_20.pdf

http://active-antenna.eu/tech-docs/3_ActiveAA_Antena_11.pdf

Many SDR receiver owners have seen improved noise and Image reduction by placing the plastic cased SDR unit on a small shielded/ grounded case.

The Amp needs 12VDC from in the shack. The Amp has two relays that you can switch, from in the shack, to select Vertical or Horizontal loops, or a dipole. The loop amp connects back to the shack via a shielded Cat 5 cable, Make sure you get shielded CAT 5 to reduce noise pickup. Make sure you provide an adequate good Ground below the antenna, less noise pickup and lightening protection.

Have fun!
Dave, K9ZCE
Retired from EE Dept @ Rose-Hulman Institute of Technology
Terre Haute, Indiana

Thank you so much, Dave!

Readers: yesterday I saw Dave’s loop antenna photos on the SDRplay RSP Facebook page. I was fascinated by his horizontally/vertically oriented loops and asked if he would write up a short guest post. He kindly obliged in a matter of hours!

If you have an antenna project you’d like to share, please contact me. So many SWLs and ham radio operators live in areas with restrictions and pervasive RFI–projects like Dave’s can revive one’s radio life!

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MegaLoop ML052: Bonito’s new portable mag loop antenna

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(Source: Bonito Press Release)

At the beginning of the model year 2016, there is good news in the range of our MegaLoop Active Loop Antennas:

New Model: MegaLoop ML052

The new Active Loop MegaLoop ML052, which is available end of February, is the successor to our MegaLoop 060. Based on the proven technology of theMegaLoop 200 platform, an additional low pass filter with an extra FM-band-stop was integrated. Thus, the ML052 is especially suitable for operation near strong FM-stations and higher frequencies , where, because of its broadband capacity, the ML200 could be overloaded by strong signals.

Frequency range:
Low Gain: 9kHz – 52 MHz
High Gain: 9 kHz – 36 MHz
Suppression on FM (88 – 108 MHz): max. 40 dB

Intercept Point
IP:3: typ. +40dBm
IP2: typ. +84 dBm

The effect of the integrated filter can be seen very good on these two images:

ML052 in High Gain Mode

ML052 in Low Gain Mode

Like the ML 200, the amplification of the ML052 can be changed internally with a jumper:
a) High Gain: 0-36MHz
b) Low Gain: 0-52 MHz (-7dB)
Suppression of the FM band: (88-108MHz): max. 40dB

Outstanding intermodulation surpression, with only 5 volts!

CPI1000 with a standard Powerbank

The MegaLoop ML052 achieved outstanding values regarding intermodulation suppression even at a low supply voltage from only 5V. It can be powered either by a conventional plug power supply or even via USB. Powering via USB has the advantage that no external power supply is needed and that the antenna can be used autonomously and noise-free with a separate USB power bank. A appropriate dual power input adapter (CPI1000) is already included in the standard package.

The MegaLoop ML052 can now be pre-ordered in our eShop underwww.hamradioshop.net. In the UK at Taylor Made RF.

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Tony’s homebrew mag loop antenna and amplifier

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Yesterday, Tony (K3DY), shared a video (via Twitter) demonstrating his new home brew loop antenna and amplifier.

This is actually a great demonstration of how even a relatively simple, inexpensive loop antenna can improve reception in locations with heavy radio interference. Tony includes the following notes with his video:

“Testing a new receiving loop antenna that I built today. It uses a pre amplifier based on deferential setup of two 2N5109 transistors. Loop is made out of coaxial cable, only the shield is connected to the circuit.

Quick demo on 31 meters, lots of stations at sunset time. No time for further testing but I observed a pronounced directivity below 7 MHz. 75 meters is so quiet that it makes me forget I live in a townhouse. As a comparison, my noise level on 75 meters is at S8 on an end fed [antenna].

https://www.youtube.com/watch?v=bq_gKNQSVeA

I will use this loop primarily for SWLing purposes but I may use it as a separate receiving antenna with my amateur radio equipment.

A lot of fun, loops are fascinating and efficient!

Indeed, Tony! And perhaps the icing on the cake is that loop antennas are so portable, low-profile and easy to deploy. They’re ideal for those living in restricted areas and with picky home owners’ associations.

Inspired by my buddy Vlado (N3CZ), I’ve actually been collecting the pieces to build my own mag loop antenna this winter. I doubt the parts for my loop will exceed ten dollars as I plan to use the shield of some heavy coax for the primary loop and a little PVC for support (much like Tony’s loop).

Tony’s video is inspiring me to go a step further and also build a simple amplifier. Any suggestions or schematics for doing so are most welcome!

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