Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s midweek edition for 5-6 October 2010
By Arnie Coro
Radio amateur CO2KK

Hi amigos radioaficionados, welcome to the midweek edition of Dxers
Unlimited, which today will feature an Antenna Topics section dedicated to a very effective low angle radiator, known as the HENTENNA, A great number of listeners from all around the world have written to me recently, asking to learn more about this Japanese antenna, the HENTENNA, that seems to be making headlines in radio publications around the world once again…

By the way, the first original report about the HENTENNA that went on the air here at Dxers Unlimited, dates back to 1999,more precisely, it went on the air the 12th of October of 1999, and according to my records, it generated a lot of interest from our listeners, who were at that time, 1999, getting ready to enjoy the peakyears of solar cycle 23 !!

So here is at the request of Dxers Unlimited’s fans , a special Dxers Unlimited's report on the HENTENNA, the Japanese elongated loop antenna with an easy
match to coaxial cable feedlines of any impedance, be it 50, 60 ,75 or93 ohms...or even 150 ohms !!!

Let me start by saying that I recently built yet another HENTENNA for the FM broadcast band, and it is working nicely, having already pick up some Sporadic E skip DX stations from Mexico, the US and Puerto Rico during the past spring and summer E skip season now in progress.
Now you will have to learn something very unusual about the HENTENNA... the HENTENNA produces or receives VERTICALLY polarized waves when the antenna is placed horizontally; that is, with the long sides of the loop paralell to the ground. AND, if you want horizontal polarization, just flip the HENTENNA so that the long sides of the loop are vertical, and the short sides are parallel to theground, something that is puzzling, but that’s the way it is amigos…

By the way, one of the world's foremost antenna experts, Dr. L. B. Cebik, amateur radio operator W4RNL, did during his fruitful life an extensive analysis of elongated loops, and his findings are really fascinating. Dr. Cebik , now a silent key specialized in computer modeling of complex antenna systems, and his work with the HENTENNA and other similar elongated loops shows that the HENTENNA is a very good performer indeed.

In a few seconds, be ready to write down, the formulas for calculating HENTENNAS in the frequency range from 14 megaHertz all the way up to the high TV band that here in the Americas ends at 216 megaHertz.. so amigos, stay tuned, I'll be back with more radio hobby related information in a few seconds... I am Arnie Coro in Havana

……………….

You are listening to Radio Havana Cuba, the name of the program is Dxers
Unlimited… you can send your signal reports and comments via e-mail to
arnie@rhc.cu or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba…

And now, as promised more about the japanese wonder antenna... the HENTENNA. Dr. Cebik's computer modeling shows that the elongated loop HENTENNA has an edge over a regular square one wavelength loop and the regular elongated loop.

HENTENNAS for receiving FM broadcast signals are very easy to build,
using a wooden or PVC pipe frame and copper wire. I built the one just
mentioned cut for 100 megaHertz, using PVC insulated no. 12 wire, the
one that is typically used for home wiring.

The loop was closed by soldering with a butane torch, and using regular
solder with rosin core... The reason for using the butane torch is that
no soldering iron at hand here could handle the heavy wire PLUS the high
speed heat transfer of the copper wire.

The loop for the 100 megaHertz antenna is 1.5 meters on the long sides
of the rectangle and 50 centimeters on the short sides. The feed point
for the 50 ohm cable is located about 55 centimeters from one of the
short sides of the loop.

The antenna is installed with the long sides in a vertical position; for
receiving horizontally polarized FM broadcasts. I tried both 50 ohms and
75 ohms coaxial cables, and could not detect any difference on the
weakest station that I am picking up here regularly with the FM band
HENTENNA.

Again, if you want to make of these elongated loops for receiving, here
are the measurements to use: for the long sides of the rectangle 1/2 of
a wavelength at the operating frequency, for the short side, the length
is 1/6 of a wavelength... and the connection point for the coaxial cable
of 50 ohms impedance is a little more than 1/6 of wavelength from one of
the short sides of the rectangle.

I have tried two different techniques for feeding the antenna, one using
two wires connected to the long sides and going to an insulator to which
the coaxial cable is attached... this is what I do with antennas for the
lower frequencies.

For the higher frequency antennas, like for example the TV HI VHF band,
or the amateur two meter band, I use the coaxial cable itself, by
carefully splitting the center conductor and the shield in two... it
takes a little practice to do, but you will be able to do it, and it
saves time and avoids one extra soldered connection.

Do remember to fully protect the coaxial cable from the weather, by
sealing it properly with PVC tape and silicone sealing compound...
HENTENNAS can be built for any frequency between 10 megaHertz and 300
megaHertz by using heavy WIRE, and for the frequency range from about 50
megaHertz to 500 megaHertz you may try building HENTENNAS with copper or
aluminum tubing.

YES amigos, this is yet another easy weekend project... collect all the
needed materials and have them ready at your workshop, the garage or
near the kitchen table, so that this coming weekend you can build your
own low cost elongated loop HENTENNA.

Remember, if you are a radio amateur, that a HENTENNA is a very
effective antenna to take along with your HANDIE TALKIE, as it will
extend the range of the HT many times. I now have my portable HENTENNA
for 2 meters that has shown a gain of more than 6 to 10 decibels above
the handie talkie's rubber duck antenna.

In other words, the HENTENNA is behaving as if you add a linear
amplifier to the HT with the additional benefit that if DOES NOT USE UP
EXTRA battery power. And one final comment, do remember that the
HENTENNA is DIRECTIONAL, so you can turn it around for best possible
signals... A HENTENNA for two meter band FM must be installed with the
long sides HORIZONTAL... in order to receive and transmit the vertically
polarized waves used for amateur 2 meter FM communications!
…........................................
Si amigos, for more than half a century I have been fascinated with my
father’s 14teenth birthday present… a regenerative radio receiver kit
that he was sure I was going to be able to assemble without any help, as
dad told my uncle Armando during the birthday party.. that little radio,
assembled breadboard fashion is still working after more than half a century have
passed, and it has also served as the prototype for many other clones
that I have helped to build all along these years. The latest version of
my BIRTHDAY Regenerative is a bit more sophisticated than the original
one, and works beautifully with the sets of plug in coils that its proud
owner my now fifteen years old grandson Arnie the Fourth has built so far… As batteries are hard to come by locally and very expensive, this version of Arnie’s
Birthday Regenerative uses a very safe 24 volts DC supply to power Arnie
Coro the Fourth wonderful new toy!!!!
If you want to learn more about my BIRTHDAY Regenerative receiver, just
drop me an e-mail to arnie@rhc.cu or a postcard to Arnie Coro, Radio
Havana Cuba, Havana , Cuba asking me to send you the Birthday
Regenerative receiver information package…
Posted by Arnaldo Coro at 8:23 AM 0 comments Links to this post
Labels: Arnie Coro, CO2KK, Dxers Unlimited 5 Oct, Hentenna, Radio Havana Cuba, radio hobby program, short wave