Alexandre Grimberg PY1AHD, creator of the “AlexLoop” antenna

A magical encounter with Mr. Alexandre Grimberg, Brazilian Amateur PY1AHD, the creator of the famous “AlexLoop” antenna

Mr. Alexandre Grimberg (PY1AHD) and Martin Butera (LU9EFO-PT2ZDX), in Rio de Janeiro Brazil

By: Martin Butera

During my visit to the city of Rio de Janeiro – Brazil, I had the pleasant experience of sharing a dinner with the great Alexandre Grimberg PY1AHD, famous inventor of the “Alex Loop” antenna.

I went with my wife Ligia and my great friend Mark (LU3DU), who was also visiting the city of Rio de Janeiro.

Alexandre Grimberg kindly invited us, with his granddaughter and his kind wife Miriam, to a well-known pizzeria, in the Gavia neighborhood of Rio de Janeiro, Brazil.

Japanese edition GQ magazine cover, photograph of Alexandre Grimberg and his antenna “AlexLoop”

We spent a very pleasant night and dinner, Alexandre Grimberg is one of those people you have to sit down to listen to because everything he has to say is interesting and has the essential seasoning that gives it an unmistakable touch that is that of experience.

It was very entertaining, especially listening to his experiences while he was experimenting to create his Loop antenna and especially when he told us how he felt being on the cover of CQ Radio Amateur magazine Japanese edition and his visit to the Tokyo Ham Show 2015 and his relationship with the Japanese people.

It was very nice to meet Alexandre Grimberg, someone I deeply admire and that night he made me feel a little more the facet of the radio-experimenter.

Those who met Alexandre Grimberg (PY1AHD), in some editions of the fair in Dayton (Ohio, USA), Friedrichshafen (Germany) or even at the Fair in Tokyo, know that he is a very popular character, many Radio Amateurs, even they line up to ask for an autograph and it is incredible to see Alexandre Grimberg’s lectures, always with a full auditorium.

Without a doubt, he is the most famous and important antenna manufacturer in Brazil and South America.

Alexandre Grimberg, is a simple, friendly man and always very predisposed to talk with his colleagues in the hobby

I invite you in this great article to learn a little about the world of Alexandre Grimberg, the father of the famous “AlexLoop” antenna.

Some biographical data of Alexandre Grimberg (PY1AHD)

Alexandre Grimberg (PY1AHD), was born in October 1949 in Rio de Janeiro, Brazil.

He started in electronics when he was 10 years old and received his first ham radio license when he was 22 years old.

From Alexandre Grimberg’s personal archive: sheets of the first calculations of the antenna loop from him, handwritten.

In the year 2000, something happened that was key, he moved to a new QTH and that new place was very restricted, for radio amateurs, that is, he could not place antennas in the building.

This however, was not a problem at all and it was there that his passion for portable QRP operations began.

A year later (2001), Yaesu launches a new transceiver, it was the FT 817 and it was love at first sight.

Alexandre Grimberg describes it as an incredible piece of technology, a portable jewel that he had dreamed of all his life.

Thus it was that Alexandre Grimberg began the challenge of creating a truly portable and effective HF antenna as a companion to the FT-817 during his mini-expeditions in the open air.

It was a big challenge because at that time there was very little information about small magnetic loops available on the Internet.

Nowadays there are calculation programs that make life easier, but when Alexandre Grimberg started in 2001/2002, he had to spend a lot of time using trial and error: cutting wires a quarter inch by inch and writing down the results.

Alexandre Grimberg (PY1AHD), explains to us in a very simple way what a loop antenna consists of

That night, Mr. Alexandre Grimberg told us that today anyone can build their first small magnetic loop without spending almost anything and using all the information provided by the Internet.

He explained to us that the most important part of a magnetic loop antenna is the variable capacitor. That capacitor can be a split stator or butterfly type, but if you don’t have one, you can start with whatever you have on hand, maybe even just a piece of RG-213 coaxial cable to loop and start experimenting and splitting a capacitor.

In the middle of dinner, Alexandre Grimberg told me to get a pencil and paper, because he was going to humbly dictate and explain to me in a few words and in 5 small steps, how a small magnetic loop antenna works, thus showing that although Today Alexandre Grimberg is a successful businessman, he never stopped being an Amateurs Radio and he shares all his knowledge with his community.

We start:

  1. The magnetic loop antenna is an RF transformer. The main is the small inner loop that is 1/5 the size of the main loop. The secondary is the primary loop and is the actual antenna. This outer conductor is closed by a variable tuning capacitor. The two loops are isolated, with no electrical contact between the inner and outer loops.
  2. The magnetic loop antenna is a high “Q” device, so the bandwidth is very narrow. Even minor frequency changes will require you to retune the antenna, but in return, the antenna provides superior reception rejection of unwanted signals, giving the best receive gain and lowest SWR on transmission.
  3. The magnetic loop antenna can be used for vertical or horizontal polarization, and the small size makes it easy to switch between the two.
  4. In most radio activities we use the loop in a vertical position supported by a small pole. The antenna can be freely rotated in both directions to minimize or even completely eliminate man-made noise. For condo windows, hotel balconies, and other locations with limited space, the loop can be used in a horizontal position, which (of course) provides vertical polarization and an omnidirectional radiation pattern.
  5. The small magnetic loop works perfectly at low heights. A one meter diameter loop works perfectly one meter above the ground.

From the personal archive of Alexandre Grimberg (PY1AHD), he shares with us one of the first antennas he built at home, before his successful “AlexLoop”

From his personal archive: we can see one of the first loop antenna pilots, built by Alexandre Grimberg

In photograph 1, we can see how soft copper air conditioning tubes work perfectly for the construction of loops.

In photograph 2, we can see the variable capacitor, these vary in picofarads, we must look for the most suitable ones to be able to cover from 10 to 80 meters.

In the following photograph 3, you can see the two small soft copper magnetic loops, both made in 3/4 inch soft copper tubing. The largest is 91 cm in diameter and measures 2.89 cm from each end. The excited loop is made on coaxial cable and measures 2.89 CMS divided by 5.

In photograph 4, we can see a standard capacitor from 12 to 100 Picofarads.

Let us now know the commercial version of the famous “AlexLoop” antenna, developed by Alexandre Grimberg

AlexLoop is the famous small and portable Magnetic Loop Antenna, developed by Alexandre Grimberg.

The AlexLoop small magnetic loop antenna can be quickly assembled and disassembled for easy transport.

The main characteristics of the AlexLoop small magnetic loop antenna are the following:

  • Easily tune in 5 seconds to any frequency between 6.9 MHz and 30 MHz, so you simply need to adjust the built-in tuner for signal peak in receive mode and then fine tune in transmit mode to get the Lower ROE.
  • There are no tapping on the coils to change the band and no whip adjustments needed to tune.
  • The AlexLoop small magnetic loop antenna can be quickly assembled and disassembled for easy transport.
  • It is the ultimate solution for radio amateurs with limited spaces to mount their antenna.
  • Unique low profile design offers a solution for both Amateurs Radio and BCL.
  • You can support the AlexLoop antenna on windows, balconies or even inside your radio shack.
  • It is a discreet antenna that can be used and finally removed from the window or balcony once radio communications are complete.

AlexLoop, is without a doubt the perfect partner for your next Dxpedition.

From Alexandre Grimberg’s personal archive: we can see the famous “AlexLoop” antenna step by step, how to assemble it and how light and easy it is to transport and the best way to operate the “AlexLoop” antenna, with the operator seated comfortably in a camping chair with one finger on the tuning knob and the another hand navigating the radio controls.
Alexandre Grimberg, recommends that you do not use the antenna on a high pole or in a place where you cannot reach the antenna tuning knob, your antenna will work perfectly just one meter above the ground, so keep the tuning knob at your hand height for quick QSY and SWR adjustments.
AlexLoop, was invented and patented and introduced to the Amateur Radio market, by Alexandre Grimberg (PY1AHD), in 2007.

Alexandre Grimberg, has always been a very active Amateurs Radio for over 50 years and particularly enjoys outdoor radio on HF bands.

The AlexLoop antenna, today is an embodiment of the many experiments and experiences of Alexandre Grimberg, throughout all these years of constant improvement.

Each AlexLoop antenna is completely handmade by Alexandre Grimberg himself, from the first screw to the final test.

In all these years on the market, AlexLoop has become the most popular portable magnetic loop antenna in the world.

The portable HF operating revolution brought about by the “AlexLoop” antenna has spawned many imitators, but none have replicated the efficiency, portability and usability of the AlexLoop.

Here are some great features of AlexLoop:

  • It is without a doubt the lightest portable magnetic loop on the market: only 2.1 pounds (less than 1 kilogram).
  • One-hand operation. Light weight and thumb adjustment allow operation of walking and talking at the same time. No other loop antenna on the market can do that.
  • The light weight of the “AlexLoop” antenna allows it to be mounted on a small tripod or attached to the balcony with an inexpensive plastic clamp.
  • The most efficient portable magnetic loop on the market thanks to the four gold-plated monobloc PL259 connectors that reduce the ohmic loss of the connection to the transmitting coaxial cable loop.
  • The driver loop is soldered directly to the BNC connector to prevent insertion loss of a mechanical contact.
  • By far the fastest antenna to set up. AlexLoop can be assembled in just 90 seconds in the field.
  • The fastest adjustment due to a special reduction gear in the AlexLoop variable capacitor. It can scan from 7 to 30 MHz in just 4 seconds.
  • The AlexLoop comes with a specially designed carry bag that allows quick mounting and dismounting of the antenna.

AlexLoop antennas were designed for light weight, portability, versatility, and as the ideal forthe HF Packer, for the restricted ham radio antenna, RV/camping, hotels, apartments,condos, and for shortwave listening.

Alexandre Grimberg in his office, putting together the famous “AlexLoop” antennas one by one.

Alexandre Grimberg and his time in the Land of the Rising Sun

Alexandre Grimberg, present at the 2015 edition of the “Amateur Radio Festival Ham Fair”, the largest event in the world of Japanese amateur radio.

Without a doubt, the year 2015 will remain a great treasure in the life of Alexandre Grimberg, professionally his “AlexLoop” antenna debuts at the Yaesu-Musen stand.

Emotionally, he came for the first time to celebrate, along with his wife Miriam, the tenth anniversary of his marriage, in the magical and romantic city of Tokyo.

MLA-48 project

At booth J-10 of the “Amateur Radio Festival Ham Fair”, Alexander Grimberg was eagerly awaited by the friends of the MLA 48 project and the National Radio Hotspot Expedition (abbreviation: HD).

The MLA-48 project is a group of Japanese friends, made up of Radio Amateurs and other BCLs, many of whom are scientists, engineers, builders and loop antenna enthusiasts.

The MLA-48 project is undoubtedly the world’s largest meeting of fans of MLA Antennas (Magnetic Loop Antenna).

This club is intended to recruit a wide range of members from all over Japan to experiment
with loop antennas.

On the official website of the club there is a lot of material about it, you can visit:

Members of MLA 48, waiting for the arrival of Alexander Grimberg at the “Amateur Radio Festival Ham Fair 2015”
Group dinner of MLA-48 members in honor of Alexandre Grimberg and his wife Miriam, organized by members of MLA-48.

Homebrew Radio “BITX 40”, by Alexander Grinberg

This Alexander Grimberg project won second place in a QRP Homebrew transceiver contest at Pacificon 2018.

First place went to Mr. Japanese Amateur Radio, Hiroki Kato (AH6CY), born in Hiroshima and currently residing in Portola Valley, San Mateo County, California, United States.

Alexander Grimberg is so happy with the final result of BITX 40 that he took the trouble to design a portable magnetic loop version of the “AlexLoop” type, but following the same construction finishing details as BITX 40.

Here you can see the homemade transceiver put together by Alexander Grimer, in full action:

Homebrew Radio “BITX 40”, by Alexander Grinberg
Master Builder Fest Diploma

Other curious and crazy constructions of Antennas by Alexander Grinberg

The Coke Loop

This antenna by Alexandre Grimberg is the sensation every time he presents it year after year at Dayton Hamvention (USA), Friedrichshafen (Germany) and of course it was the sensation at the Ham Fair in Tokyo (Japan).

The Coke Loop is a small magnetic antenna tuned by a trombone-style variable capacitor made from standard soda cans.

In Brazil we have the Coca Zero and Coca Light versions of Coke. The Coca-Cola Zero can is shorter and wider and the Diet Coke can is longer and thinner.

Coke Loop

The ends of the loop are connected to the stationary (larger) Coke Zero cans. The variable capacitor portion of the moving trombone is made from Diet Coke cans screwed onto a double-sided printed circuit board.

The printed circuit board is also screwed to the moving part of an injection syringe that is connected to another injection syringe by a flexible plastic tube filled with water. This creates a hydraulic remote tuning system to adjust the resonance point of the antenna.

The loop is made from a 112-inch section of standard coaxial cable with PL-259 connectors on the ends that plug into the tuning system unit.

The driven loop is made from a 22.4-inch section of solid electrical copper wire that is connected to a 2.5-meter section of coaxial cable for connection to the transceiver. The Coke Loop covers 12 meters, 15 meters, 17 meters and 40 meters.

To make the loop work on 40 meters, he used a 150 pf fixed capacitor with alligator clips in parallel to the trombone’s variable capacitor.

The details of the construction step by step of the Coke Loop
Coke Loop Antenna Test Videos
Radio Amateurs, raving in Friedrichshafen (Germany), with the creation of Alexander Grimberg’s “Coke Loop”
If you think you’ve seen everything, how about going now to see another crazy “Secret Loop” antenna, built with a table.

The “Table Antenna”, as Alexander Grimberg calls it, is the crazy and incredible creation of an invisible loop antenna mounted on the inside top of a 60 cm diameter plastic table.

This antenna is made of ¾ inch soft copper tubing connected to a 265 PF variable capacitor.

For frequency adjustment, he installed a long plastic rod in the condenser aisle with a small knob on the opposite side of the rod.

The 12 CMS energized loop cable runs inside the table base tube and then connects to the radio.

This antenna covers from 10 MHz to 30 MHz.

Don’t you think it’s possible? Take a look at the photos!

Floating magnetic loop
The antenna covers 6/10/12 and 15 meters and by switching the two ceramic capacitors in parallel with the variable capacitor the antenna can cover 17 and 20 meters.

The floating loop was the result of Alexandre Grimberg’s research into a thick and light loop.

The lifesaving foam floating spaghetti is generally 150 to 160 CMS and the thickness is around 8 CMS.

In detail Floating Loop antenna, creation of Alexandre Grimberg

Alexandre Grimberg, teaches us the step by step, of this crazy antenna, so that you can also experience: The first step is to place the plastic tube of internal thermal fax paper in the waste and close the spaghetti in a loop by inserting the tube of plastic on each side leaving some space in the center to accommodate the variable capacitor.

Then with a few meters of coax braid, make it flat and wrap a few spaced turns on the foam holding the coax braid in place with a few dots of hot glue.

Allow 10 CMS of braid to solder to the air variable capacitor at the beginning and end of the foam loop.

Roll up a few layers of the foil shed with controlled force covering the spaghetti foam lifebuoy.

Next, take the glass tape and start twisting it over and over to make the loop antenna snug.

Finally, fix the wooden arm with zip ties to the inner fax tube. Attach the variable capacitor to the inner plastic tube of the fax machine. Adapt the adjustment lever to the variable capacitor aisle. Calculate the size of the excited loop (1/5 of the length of the main loop) and this Floating Loop Antenna is ready to save your life.

The Thick Loop or Chimney Loop
In detail Thick Loop antenna or Chimney creation of Alexandre Grimberg

The performance of a small magnetic loop can be improved by building it larger, thicker, or both.

That was Alexander Grinberg’s goal, to improve the performance of his magnetic loop antenna in the 40 meter band.

One of the challenges he took on was to build this loop light enough to carry around on his outdoor radio activities.

There are two options for building a reasonable performer on a 40 meter band:

A) Construct a 6 foot diameter magnetic loop in 3/8 inch soft copper tubing.

B) Construct a small 3-foot-diameter magnetic loop on a 4-inch pipe.

Look for lightweight tubes that could be easily bent into a circular shape.

Connection details:

Alexander Grimberg used a half-inch barbed copper braid to connect the ends of the aluminum tubing to the variable capacitor.

At each of the ends of the aluminum tubes, the braid goes around them and the ends of the tubes are bent back an inch and a half; thus improving the electrical contacts, which is reinforced by the pressure of the twelve screws that hold the ends of the pipe.

The other ends of the braids are soldered to the variable capacitor contacts.

For the loop to work, the aluminum tube was covered with aluminum foil, and the aluminum foil was held in place with a polyester film.

This preliminary testing procedure demonstrates that the corrugated aluminum tube was not adequate to resonate in the desired frequency range.

This antenna covers 12 megahertz to 32 megahertz and adds a 156 Picofarad ceramic capacitor that resonates on the 40 meter band.

Words written especially for this report, from our friend Alex Loop

The trip we made to Japan will always remain in our memories as one of the most emblematic memories of our lives.

Our first memory when we arrived at Narita airport was when we were faced with the task of handling large and heavy luggage due to the number of brochures, Banners, tripods, antennas etc …

Left Mark Melzi (LU3DU), center Alexander Gromberg (PY1AHD), right Martin Butera (LU9EFO – PT2ZDX), author of this special report for Radio Heritage Foundation

Miriam (my wife) and I were completely disoriented trying to reach the first steps of the escalator that would take us to the airport Metro station when we were surprised by a young woman and a man who picked up the heavy suitcases and helped us to get to the airport subway station.

This attitude eloquently expressed the best welcome we could experience.

Japan is a lovely country and the people are courtesy, respect for others, incomparable kindness.

Our stay in Japan was marked by episodes and encounters with wonderful people.

We are honored to have JACOM as our distributor in Japan. We were received in a meeting with its CEO NOBORU SUGI accompanied by his highly qualified assistants at JACOM when it came to business matters.

Right after our meeting, NOBORU-SAN put together a special itinerary for me and my wife that included incredible views, historical sites, and wonderful restaurants.

All the details have been carefully arranged by NOBORU-SAN to make our trip to Japan even more unforgettable.

JACOM’s SAM-SAN took us to Akihabara where we visited ham radio equipment stores and electronic component stores.

In Akihabara SAM-SAN showed me a kiosk specializing in electronics and communication magazines sold by an old lady and flipping through the Japanese magazine I didn’t know, I found an article published by me, another incredible surprise in my memories.

In the following days I felt incredible emotions…

Take part in the Tokyo Ham Show, held annually at the Tokyo Big Site.

Tokyo Big Site, like everything in Japan, is wonderful in terms of architectural beauty and convenient location.

Arriving at the show, I saw the AlexLoop WalkHam antenna on display at the JACOM booth.

JACOM is a highly regarded company that resells AlexLoop antennas in Japan Wimo Antennen, a well-known company in Germany, reseller of AlexLoop.

From left to right Miriam (Alex’s wife), with her granddaughter, Marcos Melzi (LU3DU, personal friend of Martin), in the center the great Alexander Grimberg, in red Martin Butera, next to his beautiful wife Ligia Katze.

It had recently established a business office in Japan and had the AlexLoop antenna on display.

Wimo Antennen was responsible for the suggestion to display the AlexLoop antenna at the Yaesu booth at the Tokyo Ham Show 2015.

The moment of greatest impact was when I arrived at the YAESU booth and saw the AlexLoop antenna in a prominent place connected to the YAESU FT817.

The YAESU FT817 transceiver has been breaking sales records for years, forming with the AlexLoop WalkHam the dream set of fans of QRP operations and radio amateurs with the restriction of installing external antennas.

So far we can conclude that AlexLoop WalkHam was simultaneously exhibited at Tokyo Ham Show 2015 at YAESU, JACOM and WIMO booths.

Finally, I had the immense honor of also participating in the Stand of the MLA-48 Group of my great colleague and supporter Kogure-san who, with all his knowledge in antennas and electronics, coordinates the MLA-48 GROUP.

The MLA-48 Group is engaged in studies and research by brilliant Japanese hobbyists under the guidance of Kogure-san, who meet regularly to share their practical experiences and theoretical conclusions regarding magnetic loop antennas.

The Coke-Loop was placed prominently on the MLA-48 Group stand in such a way as to allow visitors to control the hydraulic system I developed to move the variable condenser made from Coca-Cola cans.

My wife Mirian and I were honored by Kogure-san, his wife and the members of the MLA-48 Group with a delicious and fun dinner that will remain forever in our memories.

I thank Martin Butera, for this new recognition and for once again bringing me these beautiful memories of my visit to Tokyo.

Latest AlexLoop HamPack

The idea of this tribute to Alexandre Grimberg, is to show his recent release 2021, a new special magnetic loop antenna designed by him, which brings a lot of new fun for all radio amateurs who think of enjoying the pleasure of outdoor operation using the clever association of the most sophisticated portable magnetic loop antenna with a beautiful full-size backpack designed for outdoor radio amateur operation.

Here the exclusive video!!

About the Author

Martín Butera, He has listened to shortwave radio and Amateur Radio since 1992 with the Argentine callsign LU9EFO and the Brazilian callsign PT2ZDX.

Martín is a Radio Amateur with more than 30 years of experience, and has participated in DX expeditions throughout South and Central America.

Martin contributes, writes and compiles information for several radio bulletins that cover the topic of world radio and is our accredited correspondent for the Radio Heritage Foundation in Brazil and throughout the South American region.

Martin is the founder in Brazil, of the CREW called 15 point 61 (15.61), now called only 61 sixty-one.

Martín Butera is a journalist, documentarian and was a founding member of Radio Atomika 106.1 MHz (Buenos Aires, Argentina)

He currently lives in Brasilia, the capital of Brazil.

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