Colorado ARES Supports Emergency Communication in Wildland Fire Response


See on Scoop.itKH6JRM’s Amateur Radio Blog

The American Radio Relay League (ARRL) is the national association for amateur radio, connecting hams around the U.S. with news, information and resources.

Russ Roberts‘s insight:

This fire is huge and it threatens many populated areas.  Area hams are helping where they can.  It’s going to be a long week for those working with fire crews, police, and civil defense officials.  Aloha de KH6JRM.

See on www.arrl.org

Your video about Amateur Radio can win big – Southgate Amateur Radio Club


See on Scoop.itKH6JRM’s Amateur Radio Blog

Your video about Amateur Radio can win big
Southgate Amateur Radio Club
The South African Amateur Radio Development Trust invites amateur videographers to take part in a video competition and compete for some great prizes.

Russ Roberts‘s insight:

The ARRL runs a similar video contest.  Why not give this competion a try? Your video could have a huge impact on the future of amateur radio worldwide.  Good luck!  Aloha de KH6JRM.

See on www.southgatearc.org

New York City Amateur Radio Emergency Communications Service NYC-ARECS


See on Scoop.itKH6JRM’s Amateur Radio Blog

New York City Amateur Radio Emergency Communications Service (NYC-ARECS)NYCARECS (New York City Amateur Radio Emergency Communications Service is a #NYC based auxiliary communications service.

Russ Roberts‘s insight:

A good description of New York City’s ARES system.  This group has gotten a real workout since the bombing of the twin towers back in 2001 and the devastation wrought by Hurricane Sandy.  Aloha de KH6JRM.

See on nyc-arecs.org

G0KYA’s Amateur Radio Blog: The “Kaz” directional MW antenna


See on Scoop.itKH6JRM’s Amateur Radio Blog

G0KYA’s blog devoting to amateur radio / ham radio, featuring articles on antennas, propagation, marconi and much more.

Russ Roberts‘s insight:

Steve Nichols (G0KYA) always has something interesting on his website.  This week, Steve explores the triangular shaped KAZ antenna, a device designed to monitor Medium Wave (broadcast) stations in the USA.  Nice, concise description of the antenna.  Aloha de KH6JRM.

See on g0kya.blogspot.com

Ham Radio CubeSat FITSAT-1 de-orbits this week – Southgate Amateur Radio Club


See on Scoop.itKH6JRM’s Amateur Radio Blog

Ham Radio CubeSat FITSAT-1 de-orbits this week
Southgate Amateur Radio Club
Ham Radio CubeSat FITSAT-1 de-orbits this week. It is expected that the amateur radio CubeSat FITSAT-1 will re-enter the Earth’s atmosphere and burn-up by Wednesday, July 3.

Russ Roberts‘s insight:

Takushi Tanaka (JA6AVG) reports that CubeSat FITSAT-1 is expected to enter the earth’s atmosphere around 03 July 2013.  Send reports to:  http://www.fit.ac.jp.  Aloha de KH6JRM.

See on www.southgatearc.org

Successful ARISS ham radio contact with school in Zagreb, Croatia – Southgate Amateur Radio Club


See on Scoop.itKH6JRM’s Amateur Radio Blog

Successful ARISS ham radio contact with school in Zagreb, Croatia
Southgate Amateur Radio Club
The June 26 ARISS ham radio contact with Ruder Boscovic school in Zagreb was a success.

Russ Roberts‘s insight:

This must have been a very spirited event.  Hopefully, these contacts with students will encourage them to pursue careers in electronics, computers, mathematics, and science.  A few students might even become amateur radio operators and thereby enrich our hobby.  Aloha de KH6JRM.

See on www.southgatearc.org

How amateur radio is assisting in Uttarakhand rescue efforts – Firstpost


See on Scoop.itKH6JRM’s Amateur Radio Blog

National Institute of Amateur Radio, Hyderabad, has sent a team with radio equipment to the hill state and is operating in co-ordination with Bharat Scouts and Guides, Dehradun.

Russ Roberts‘s insight:

An update on the support rendered by Indian amateur radio operators in flood-ravaged Uttarakhand.  Hams are doing what they do best–helping government authorities reconnect with areas cut off by natural disasters.  Most of the health and welfare traffic in this area is being handled by amateur radio operators.  Aloha de KH6JRM.

See on www.firstpost.com

Low-power Wi-Fi signal tracks movement—even behind walls


See on Scoop.itKH6JRM’s Amateur Radio Blog

The comic-book hero Superman uses his X-ray vision to spot bad guys lurking behind walls and other objects. Now we could all have X-ray vision, thanks to researchers at MIT’s Computer Science and Artificial Intelligence Laboratory.

 

Researchers have long attempted to build a device capable of seeing people through walls. However, previous efforts to develop such a system have involved the use of expensive and bulky radar technology that uses a part of the electromagnetic spectrum only available to the military.

 

Now a system being developed by Dina Katabi, a professor in MIT’s Department of Electrical Engineering and Computer Science, and her graduate student Fadel Adib, could give all of us the ability to spot people in different rooms using low-cost Wi-Fi technology. “We wanted to create a device that is low-power, portable and simple enough for anyone to use, to give people the ability to see through walls and closed doors,” Katabi says.

 

The system, called “Wi-Vi,” is based on a concept similar to radar and sonar imaging. But in contrast to radar and sonar, it transmits a low-power Wi-Fi signal and uses its reflections to track moving humans. It can do so even if the humans are in closed rooms or hiding behind a wall.

 

As a Wi-Fi signal is transmitted at a wall, a portion of the signal penetrates through it, reflecting off any humans on the other side. However, only a tiny fraction of the signal makes it through to the other room, with the rest being reflected by the wall, or by other objects. “So we had to come up with a technology that could cancel out all these other reflections, and keep only those from the moving human body,” Katabi says.

 

To do this, the system uses two transmit antennas and a single receiver. The two antennas transmit almost identical signals, except that the signal from the second receiver is the inverse of the first. As a result, the two signals interfere with each other in such a way as to cancel each other out. Since any static objects that the signals hit—including the wall—create identical reflections, they too are cancelled out by this nulling effect.

 

In this way, only those reflections that change between the two signals, such as those from a moving object, arrive back at the receiver, Adib says. “So, if the person moves behind the wall, all reflections from static objects are cancelled out, and the only thing registered by the device is the moving human.”

Russ Roberts‘s insight:

Intriguing, if somewhat spooky, use for Wi-Fi.  Apparently, the Wi-Vi system is similar to radar and sonar imaging.  Low-power Wi-Fi signals are transmitted and the reflections of these weak signals are use to track the motions of people.  Wait until the surveillance corporations get a hold on this technology.  Aloha de KH6JRM.

See on phys.org

Antenna Topics: A Junk Box Vertical. Post #206


I’ve been a “radio junkie” since age 8 when my father and I built a crystal set in the garage.  I was amazed what a Quaker Oats cardboard cylinder, some enameled wire, a crude slider, a piece of pyrite, a “cat’s whisker”, and a pair of high impedance headphones could do.  With about a hundred feet (30.48 meters) of #14 AWG house wire and a good ground, I was able to capture many AM broadcast stations, many all at once.  The pyrite crystal wasn’t too selective, but I did have fun.

From there I graduated to better receivers and some homebuilt Heathkit audio equipment.  Although my father was a “stereophile” and appreciated good jazz and classical music, he never did become an amateur radio operator.  I kept putting off getting my amateur radio license until I left the Air Force and became part of a commercial broadcast station.  One of the engineers at KHLO-AM (Hilo, Hawaii) finally persuaded me to take the novice examination.  Once I got the license, it wasn’t long until I became a radio “packrat”, collecting all manner of equipment, parts, wire, microphones, and radio books.  That affliction has followed me for over 36 years as a “ham.”

When I completed my last inventory of radio equipment, I found a large collection of mobile antenna coils, baluns, various lengths of wire, a box full of RG-8 coaxial cable, some ladder line, connectors, and insulators.  Next to the back wall was my first mobile antenna–a Hustler system consisting of the 54 inch (134.16 cm) mast, a bumper mount, shock-absorbing spring. loading coils for 40, 20, and 15 meters, and a 20-foot (6.09 meters) piece of RG-58 coax with “pigtails.”

I put these antenna pieces in the house and began researching ways to convert a mobile HF antenna to fixed station use.  On Friday (28 June 2013) I found an interesting article by R. “Andy” Wiedeman (WA0AW) in the February 2012 issue of QST.  Andy describes how he used pvc mast sections, a small metal plate, a connector with a 3/8 X 24 thread, several Hustler coils, a “stinger”, and 4 radials to build a portable antenna that could be used on his recreational vehicle (RV) or at his home qth.

With a few modifications, I was able to adapt my junk box parts to build a compact vertical in my back yard.  With apologies to WA0AW, here’s how I used my old mobile antenna for a fixed station antenna.

I have two metal clothes line poles in my back yard, separated by about 16 feet (4.87 meters).  I bolted the bumper mount onto the cross arm of the clothes line pole furthest from my house.  The cross arm is approximately 8-feet ( 2.43 meters) above ground.

I attached the RG-58 coax with the “pigtails” to the mast and the bumper mount, with the center wire of the coax going to the Hustler mast and the braided shield going to four evenly spread out radials which left the the clothesline cross arm at approximately 45-degrees.  Since I was interested in pursuing 20 meter contacts with this modified antenna, I screwed in the 20 meter Hustler coil and its matching wire “stinger.”  Each radial was cut according to the general formula 234/f (MHz)=L (ft), giving me an element length of 16.47 feet (5.02 meters).  Many antenna authorities recommend cutting the radials about 5% longer than the normal 1/4 wavelength for each dipole element.  I decided to stick with my original measurements.  Once I spread out the radials, I found that I had to run a portion of the radial length on the ground.

I used a barrel connector (UHF to UHF) to attach the RG-58 coax to 25 feet (7.62 meters) of RG-8 coax.  The RG-8X ran through a panel in the radio room window case and was connected to the Drake MN-4 antenna transmatch.  Small coax patch cords connected the low pass filter, dummy load, and the old Swan 100-MX transceiver to the transmatch.  All antenna connections were soldered and covered with clear fingernail polish.

After a few tests and adjustments, I found the mobile antenna conversion worked about as well as my low home station dipole.  The modified ground plane formed by the slightly elevated radial system performed well.  According to a recent article by Rudy Severns (N6LF), four elevated 1/4 wave radials “will perform about the same as many radials mounted on the ground and far better than using the RV chassis as a counterpoise.  Elevating a horizontal radial system results in an antenna impedance of about 30 ohms, resulting in poor match to a 50 ohm coax.  Sloping radials sloped at 30 to 50 degrees provide an improved match.” Since my antenna was lower to the ground than the one described by WA0AW, I had a small mismatch to handle–easily done with the trusty Drake MN-4.

To change bands, I just screw on another loading coil and its “stinger” and add four sloping radials cut for my band of choice.

Since the antenna is mounted at a relatively low height in my backyard, it remains invisible from the street and  the prying eyes of neighbors.

I enjoyed making this antenna.  Other than my own labor and supply of  extra parts, the cost of the antenna was zero.  When I tire of this antenna, I will break it down, clean all the parts, and recycle the components for other antenna projects.

REFERENCES:

Wiederman, R. “Andy” (WA0AW).  “Double Your Mobile Antenna Use.” QST, February 2012, pp. 41 to 43.
Steverns, Rudy (N6LF).  “An Experimental Look at Ground Systems for HF Verticals.”  QST, March 2010.  pp. 30-33.
Robeson, R (K4YZ).   “One Ham’s Fix for Limited Space Antennas.”  QST, March 2011.  pp. 37-39.

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For the latest amateur radio news headlines, check out my news blog–http://kh6jrm.com.  I’ve listed a few stories following this post.

Aloha from the beautiful Hamakua Coast of Hawaii Island,

Russ (KH6JRM.

BK29jx15.

The [Wire] Antenna Builders Survival Guide


See on Scoop.itKH6JRM’s Amateur Radio Blog

eHam.net Article: The [Wire] Antenna Builders Survival Guide – KE7FD presents some helpful tips
– eHam.net is a Web site dedicated to ham radio (amateur radio).

Russ Roberts‘s insight:

I found this helpful article on the eham.net website.  Glenn (KE7FD) offers a few useful hints on maximizing your antenna performance.  Aloha de KH6JRM.

See on www.eham.net

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