Author: Johan Bouwer

Student Invents Device that Charges Batteries with Radio and WIFI Waves

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German university student, Dennis Siegel, invented a device that captures electromagnetic fields like WIFI and radio waves and converts them to stored energy in batteries.

His electromagnetic harvester won second place at this year’s Digitale Medien (Digital Media) technology competition at the University of the Arts Bremen, Hochschulpreis when he successfully demonstrated charging one AA battery over the span of a day.

Siegel explains the device on his blog:
The omnipresence of electromagnetic fields is implied just by simple current flow. We are surrounded by electromagnetic fields which we are producing for information transfer or as a byproduct. Many of those fields are very capacitive and can be harvested with coils and high frequency diodes. Accordingly, I built special harvesting devices that are able to tap into several electromagnetic fields to exploit them. The energy is stored in an usual battery. So you can for example gain redundant energy from the power supply of a coffee machine, a cell phone or an overhead wire by holding the harvester directly into the electromagnetic field whose strength is indicated by a LED on the top of the harvester.

Depending on the strength of the electromagnetic field it is possible to charge a small battery within one day. The system is meant to be an option for granting access to already existing but unheeded energy sources. By exploring these sources it can create a new awareness of the invisible electromagnetic spaces while giving them a spatial dimension.

There are two types of harvester for different electromagnetic fields: a smaller harvester that is suitable for lower frequencies below 100Hz which you can find in the general mains (50/60Hz, 16,7Hz) and a bigger one that is suitable for lower and higher frequencies like radio broadcast (~100MHz), GSM (900/1800MHz) up to Bluetooth and WLAN (2,4GHz).

End Fed Wire Antenna 40 / 6 meters

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An interesting article about a club made 30-feet wire antenna with matching connector box. Ideal for city dwellers. I am about to order one and maybe can use it for field day. Unfortunately the article will not allow itself to be copied properly (PDF is locked), so you will have to use the link below to see the pictures.

http://www.earchi.org/92011endfedfiles/Endfed6_40.pdf

 

Introduction

END FED 6 – 40 Meter Multiband HF Antenna

This project produces an inexpensive, multiband, end fed HF antenna matchbox that is quick and easy to setup and use. The end fed feature adds convenience, but does present another issue. The problem with an end fed half wave antenna is that the antenna presents a high impedance, creating a significant miss match with the usual transceiver impedance of 50 ohms. This miss match is significantly greater than typical tuners can accommodate without a matching transformer.

This project creates a trifilar wound, 9:1 UNUN (unbalance to unbalance) toroid matching transformer that will match the high input impedance of an end fed antenna into the range where most antenna tuners can produce good performance. The matchbox handles 100 watts of power. This project requires an antenna tuner to achieve satisfactory SWR.

The matchbox project uses readily available common hardware and materials. For your convenience, Emergency Amateur Radio Club of Honolulu volunteers make fully assembled matchboxes for those who don’t want to construct one. Proceeds support the club and amateur radio. Order information is included on the last two pages.

Matchbox Parts List

1 small plastic enclosure and cover
1 powdered iron toroid T106-2
3 20” pieces of 22 gauge solid insulated copper wire in red, green, and black 2 6-32 x 3/8” machine screws
2 #6 lock washer/nut combination

  1. 1  10-24 x 3⁄4” machine screw and nut
  2. 2  #10 flat washers

1 #10 lock washer

  1. 1  #10 wing nut
  2. 2  #10 wire lugs

1 #6 wire lug
1 SO-239 panel mount connector
1 30’ #18 AWG insulated stranded wire antenna

Few drops of clear PVC adhesive to secure cover in place Clear silicone caulk to secure toroid in place

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Preparing the MATCHBOX Plastic Enclosure

EARC sells completely fabricated ABS enclosures with all holes machined for the matchbox project. If you are making your own enclosure, start the project by drilling one 5/8” hole and two 9/64” holes for mounting the SO-239 coax connector on the lower side of the enclosure. Use the connector as a guide to mark for accurate drilling of smaller holes. Next, drill a 3/16” hole in the upper right side of the box for mounting the antenna connector.

TOROID WINDING

Next wind the three 20” pieces of insulated solid wire onto the toroid. Place the wires as shown green-black- red, and wrap the toroid 9 turns so that it looks like the photo on the right. Notice there are three wires extending from the left winding and three wires extending from the right winding. As the connections are completed, the steps refer to the specific wires by left or right and color.

Next, trim, crimp together and solder the left black wire with the right red wire When the step is completed, it will look like the photo on the right:page2image11384

The next three steps should appear as shown in the right photo. Crimp and solder a #10 lug to the left red wire about 2” from the toroid. The completed lug will later connect to the antenna connection bolt on the top side of the enclosure.

Twist the left green wire with the right black wire. Strip the ends of the two wires; twist together at about 2”. Solder this wire pair to the center connection of the SO-239 connector.

Trim and strip the remaining right green wire at about 2”. Crimp and solder a #6 lug. This lug will connect through a 6/32 machine screw to the ground of the coax connector.

Next, place the SO-239 though the 5/8” mounting hole from inside the box and position over the two mounting holes. Place a 6/32 x 3/8” machine screw through each mounting hole and connector. Place the #6 lug connected to the green wire over one of the machine screws. Next place a #6 lock washer/nut over both machine screws. Securely tighten both machine screws.

Position the toroid inside the box to allow connection of the red antenna wire lug to the 10-24 machine screw on the upper right box side. Place the 10-24 machine screw through the #10 lug connector on the red wire, followed by a lock washer, then a flat washer, and next insert it through the 3/16” hole in the upper side. Place a flat washer on the outside of the box followed by a #10 hex nut. Tighten the nut to hold securely. Next, place the wing nut on the antenna connector and your project appears as show above.

A small spot of clear silicone caulking compound is used to secure the toroid from movement in the enclosure. The only remaining assembly step is to securely glue the box cover in place with PVC cement.

Preparing the Antenna Wire

Matchbox performance will be determined by two factors: The length of the antenna wire, and the capability of the tuner. The length of the wire should generally be between 22 and 60 feet for best performance. Longer wires may have excessive impedance for some tuners to properly match. Wires shorter may not radiate as effectively. A 30 foot insulated 18 gauge stranded wire antenna and connecting lug is included with the project and should meet most requirements.

Experience has shown that most external tuners and many internal tuners will tune 80–6 meters with an antenna length of 22’ to 30’. If a longer antenna is desired, the provided antenna can be lengthened. Some tuners, in particular internal tuners, may not tune the full 80-6 meter range. You may need to try different wire lengths to optimize your antenna configuration. If you are having difficulty getting your rig to tune, start with a 26’ wire. This should produce good results on at least 40-6 meters using the narrowest performance range of internal tuners. Best performance is achieved with a coax of 16’ or longer.

Additional counterpoise is not required in this design. The system works well in horizontal, sloper, and vertical configurations.

Observe established safety practices when working with antennas, and avoid proximity to power or utility wires. Permanent installations should be equipped with appropriate static and lighting protection.

Keep amateur radio safe and fun! If you would like to share your experiences with this project, email the club at http://www.earchi.org.

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Toroid Wiring Schematic

ANTENNA CONNECTION

Red wire

Black wire

Coax center

INPUT Green wire Coax Shield

 

 

Fully Assembled 6-40 Meter Matchbox Antenna

Volunteers at the Honolulu Emergency Amateur Radio Club (EARC) carefully assemble these HF matchboxes for those who prefer not to build one. The club will build one for $44 including USPS priority mail shipping anywhere in the U.S. A 30 foot 18 gauge antenna wire is included.

Matchbox Antenna Parts Kit

Emergency Amateur Radio Club (EARC) makes a parts kit for the EARC 6 – 40 Meter End Fed Matchbox available for those who want to build the matchbox on their own. The enclosure is shown on the right. The ABS box is approximately 1” x 2” x 3”. It comes with a weatherproof glue-on cover. Adhesive is not included, but the best choices are clear PVC cement, clear silicone caulk, or high quality model glue.

Full Parts Kit Contents

1 ABS matchbox enclosure and cover
1 powdered iron toroid T106-2
3 20” pieces of 22 gauge solid insulated copper wire in red, green, and black 2 6-32 x 3/8” machine screws
2 #6 lock washer/nut combination

  1. 1  10-24 x 3⁄4” machine screw and nut
  2. 2  #10 flat washers

1 #10 lock washer

  1. 1  #10 wing nut
  2. 2  #10 wire lugs

1 #6 wire lug
1 SO-239 panel mount connector
1 30’ #18 AWG insulated stranded antenna wire 1 EARC Project Paper detailing assembly

EARC sells the Parts Kit for $35 including priority mail shipping in the U.S.

Three core components

The club sells just the three core hard to find parts, the box and cover plus T106-2 Toroid and SO-239 connector to fit the enclosure for $20 including priority mail shipping in the U.S.

Matchbox Enclosure only
The club sells the enclosure box with cover for $12 including shipping in the U.S.

ORDERING MATCHBOX AND PARTS FROM EARC

EARC gives you four ways to obtain a 6-40 meter Matchbox Antenna.

A fully assembled 6-40 Meter Matchbox antenna is $44 including priority mail shipping in the U.S. A kit of parts excluding adhesives is $35 including priority mail shipping in the U.S.
A set of three core components is $20 including priority mail shipping in the U.S.
A matchbox enclosure and cover is $12 including priority mail shipping in the U.S.

Proceeds go to the club to promote amateur radio activities. To order, make payment via PayPal, to our fundraising chairman chanebuth@yahoo.com . Be sure to include your name and mailing address in the remarks section with the PayPal remittance.

We will ship promptly and you will likely receive the order in 7 days or less. If you have any questions about the matchbox or your order, please email Mr. Hanebuth at chanebuth@yahoo.com.

Thank you for your interest in the activities of Honolulu Emergency Amateur Radio Club and amateur radio.

Email your experiences with this project to the club at http://www.earchi.org.

Chuck Hanebuth KH6HNL
Emergency Amateur Radio Club (EARC) Fundraising Chairman

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So it finally works as I wanted it to. The banner shows page titles, this is it, from now on blogs only. So I invite all members to come up with a story of interest and I will post it.