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Showing posts from 2013

Simple Ham Radio Antennas--Antenna Resolutions for the New Year. Post #251

The Year 2013 has been an exciting and challenging year for amateur radio operators worldwide.  From earthquakes to tornadoes and from typhoons to floods, the amateur radio community has rendered valuable aid to those in distress.  A special thank you to the "hams" in India and the Philippines who struggled to maintain communications with officials and aid agencies, often without rest and relief.  You have served in the highest tradition of the amateur service.  I also commend my fellow amateurs who kept emergency frequencies free for health and welfare traffic.  I am proud of all of you.  Yes, this past year has been far from dull.

With this in mind, I decided to review my own year in amateur radio to see where I could improve my commitment to my community, maintain a safe, efficient station, and pursue my antenna interests with a minimum of cost.  So, I started making a list of things accomplished and areas where I could do better.

Perhaps my introspective analysis will e…

Simple Ham Radio Antennas--going stealth mode. Post #250.

For most of my 36 years as an amateur radio operator, I've had to operate under the limitations imposed by HOAs, CC&Rs, and postage stamp sized backyards.  Like many of you, my creativity was sorely tested  as I tried to get reasonably efficient antennas erected for my home station.  In many cases, one antenna had to suffice for multiband operation.  And that antenna had to be inconspicuous, easy to erect and take down, and not present an "eyesore" to the neighbors.

Over the course of those years, I managed to enjoy ham radio despite the highly compromised antennas and low power employed at the shack.  There were a few multiband designs which proved successful for local and occasional DX.  Among them were inverted vees and 1/2 wavelength horizontal dipoles fed by 450 ohm ladder line connected to a 4:1 balun and a Drake MN-4 antenna transmatch.  When I did have a bit more space, I used full wavelength loops fed by ladder line for 20, 15, and 10 meters.  Height above …

Simple Ham Radio Antennas: A multiband Inverted-V Antenna. Post #249

One of the most popular amateur radio antennas is the Inverted-V.  This antenna is a first cousin to the half wavelength horizontal dipole whose antenna elements are drooped down so that the included angle between them is between 90 and 120 degrees.  According to William I. Orr (W6SAI) and Stuart D. Cowan (W2LX), the "bandwidth is somewhat lower than for a conventional dipole...Because the wires of the Inverted-V do not lie along one axis, the physical length is somewhat longer than that of a dipole cut for the same frequency."  For general design purposes and allowing for some trimming of antenna elements, you can use the general dipole formula, 468/f (MHz)=L (feet) to compute the total length of the Inverted-V dipole.  Some antenna experts believe the drooping halves of the Inverted-V change the resonant frequency, and, therefore, recommend a slightly different formula be used to calculate the length, such as 464/f (MHz)=L (feet).  I use the 468/f (MHz)=L (feet) formula t…

Simple Ham Radio Antennas: A double extended "zep" for 10 meters. Post #248.

From what I've been hearing today (Saturday, 14 December 2013), amateur radio operators are having a good time on the ARRL 10 meter contest.  Although propagation has been variable on Hawaii Island, the band seemed alive with signals.  Ten meters, like its distant cousins at 160 meters and 6 meters, offers plenty of challenges for amateurs new and old.  When propagation is favorable, both local and DX signals are possible with low power and modest antennas that can fit into a small backyard.
Ten meter events are scheduled throughout the year, sponsored by the ARRL, various national amateur radio groups, and the Ten-Ten group, which promotes the use of 10 meters.
Antennas for 10 meters run the gamut from multi-element beams and ground planes to dipoles and full wavelength loops.  Even though the current ARRL 10 meter contest is coming to an end, it's not to early  to think about ways to improve the signal from your 10 meter antenna.
If you want some gain over a dipole and have…

Simple Ham Radio Antennas--a multiband indoor loop antenna. Post 247

Over the past few posts I've been recounting the joys of erecting antennas with no space restrictions.  On my new property in the Puna District of Hawaii Island, I have an acre of land with few close neighbors and a comfortable distance from the Keaau to Pahoa Highway and all of the power lines following that road.

However, for most of my 36 years as an amateur radio operator, I've had to erect compromise antennas because of space limitations, proximity to high voltage power lines, and the eyes of suspicious neighbors.  Most of these antennas worked very well, considering the space restrictions of my rental housing.  One thing I did discover is just how good a basic 1/2 wave length horizontal dipole or inverted v performs when you use a moderate length mast (33 ft/10.06 meters) coupled with 450 ohm feed line, a 4:1 balun, and a decent transmatch.  This combination gives you multiband capability with the design frequency being the lowest band you wish to use.

I've also use…

Antenna Safety. Post #246

In the excitement of designing, building, and erecting my "homebrew" wire antennas, I've often neglected to consider important safety issues which could affect the location of my antenna and perhaps save my life.
A few years ago, I erected a vertical antenna which gave me excellent service until a lightning strike turned my work of art into a mess of shattered fiberglass, pvc pipe, wire fragments, charred coaxial cable, and a severely damaged ego.  Fortunately, I had disconnected the feed line from my shack and had it connected to a ground rod.

Ever since that lucky escape from Mother Nature, I've had a firm respect for the weather and "Murphy's Law" (whatever will go bad will fail at the most inconvenient time).

Over the course of my amateur radio "career", I've followed a few basic guidelines to erecting antennas, whether they be commercially bought or built from my own resources.

PLAN AHEAD

I know this sounds pretty basic, but thoroug…

Simple Ham Radio Antennas: The sloping 30 through 10 meter delta loop. Post #245

How would you like to build a simple, effective antenna for 30 through 10 meter coverage with some gain over a dipole at a moderate cost?  The answer is as simple as designing, erecting, and using a sloping delta loop antenna designed for 30 meters and fed with 450 ohm ladder line into a 4:1 balun connected to a sturdy antenna transmatch.  The ladder line will permit you to cover frequencies between 10.100 MHz through 29.7 MHz with low SWR.  You can also design the antenna for 30 meter use only by feeding the antenna with 50 ohm coaxial cable in conjunction with a 1/4 wavelength matching section made of 75 ohm coaxial cable.  The latest ARRL Antenna Book has more details on how to make the matching section should you decide for that option.

Now that I have more room for my expanding "antenna farm" at my new home site in the Puna District of Hawaii Island, I can set aside some space for antenna experiments without worrying about HOAs, CC&Rs, or unsympathetic  neighbors. …

Simple Ham Radio Antennas--the 40 meter NVIS loop. Post #244

In this age of natural and man made disasters, it's important to have back up equipment, antennas, and power available during periods of emergencies.  A set of homebrewed wire antennas can keep you on the air when your beam or tower have been damaged by forces beyond our control.

One of the best standby antennas is the NVIS antenna, which, because of its portability and ease of operation, can be tucked away in a convenient spot for future use.  NVIS (near vertical incident skywave) antennas are perfect for local or regional use out to about 300 miles/480 kilometers.  NVIS antennas are close to the ground (between 1/10 to 1/5 wavelength above ground) and shoot most of their signals straight up.  Sometimes called "scatter beams" or "cloudwarmers", these antennas can cover a wide area (especially mountainous terrain) with little power.

A NVIS antenna can be configured in several ways, including low-level 1/2 wavelength dipoles or low-level full wave loops.  If …

Simple Ham Radio Antennas: The slanting 80 meter delta loop. Post #243

One of the joys of moving out of my cramped quarters at Laupahoehoe to more spacious property (1 acre) in the Puna District is the ability to erect some decent antennas.  For most of my 36 years as an amateur radio operator, I've had to "make do" with compromise antennas that often performed poorly compared to full-sized antennas.  Thanks to 450 ohm ladder line, a sturdy W9INN 4:1 balun, and a trusty Drake MN-4 antenna transmatch, I've been able to get some excellent multi band contacts with the 40 meter inverted v in the backyard and the 40 meter loop under my post and pier house.  I can't complain.  These antennas have done a good job with my older equipment in the shack.

Once I complete the slow move to my new home in the Orchidland Estates, I won't have to worry about lack of space for antennas and any ground systems I might install.  To date, I erected the following antennas at the new QTH:

A 135 ft/41.15 meters long horizontal dipole (the classic "…

An Emergency "Go Kit" for the home station. Post #242

A few days ago I described the simple emergency "go kit" installed in my Honda Odyssey van.  This simple station has served me well for both portable and Field Day use.  I have no doubt the system will work during emergencies.  In fact, I've set up my "go kit" station in the backyard with excellent results using a  simple inverted v antenna and an under-the-house 40 meter loop on my lot.

Although this arrangement worked very well, I wanted to make a special "standby" station in case my main station didn't work for some reason.  Fortunately, I had a few spare rigs in the shack, and I decided to employ them in my home emergency station.

My main amateur radio station has the following equipment (most of it old, but totally functional):

One Ten Tec Argosy II transceiver and Ten Tec power supply.  I can run this rig off the electrical mains or with a solar panel/deep cycle marine battery combination.

One Drake MN-4 antenna transmatch.  I can use 450 …

A simple "Go Kit" for emergencies. Post #241

In light of the recent natural disaster in the Philippines (super Typhoon Haiyan), it might be useful to review just how prepared we amateur radio operators are for natural and man-made disasters.  Many of the hams running emergency traffic in the Philippines are using low powered rigs and simple antennas to maintain a communications lifeline in devastated areas of the Central Philippines.  Perhaps, we should do the same.

In my 36 years as an amateur radio operator, I've always followed the policy of having spare equipment, antennas, parts, tools, and standby power should an emergency arise.  While those of us living in Hawaii aren't prone to the series of disasters befalling southeast Asia, we do get our share of hurricanes, severe thunderstorms, earthquakes, and, occasionally, tsunamis.  Most hams living in the 50th state are prepared to provide emergency communications should the need arise.

It's prudent to have an emergency radio system installed in your home as well …

Super Typhoon devastates the Central Philippines. Post #240

Today, our prayers are with the residents of the Central Philippine Islands, who are just starting to recover from the devastation of super typhoon "Haiyan."  According to Ramon Anquitan (DU1UGZ) of the Philippine Amateur Radio Association, amateur radio operators in that island nation are providing emergency communications links to the government, as well as handling health and welfare traffic from impacted areas, such as Tacloban City--one of the hardest hit areas southwest of Manila.

Although the Philippine Red Cross says there are at least 1,000 dead from the devastating storm, reports from the Associated Press and Radio Australia put the dead and missing total somewhere near 10,000.

Typhoon "Haiyan" was an especially strong storm system with winds exceeding 175 mph (280.5 km/hr) in some areas.  Storm surge, heavy rain, and flooded rivers have destroyed thousands of homes and damaged hundreds of businesses in the Cebu area.  Government officials have sent  rel…

My favorite Amateur Radio antenna books. Post #239

If you've been an amateur radio operator for any length of time, you probably have a good collection of parts, books, magazine articles, wire, coaxial cable, connectors, and basic tools to support your hobby.  This "junk box" is part of our amateur radio tradition...making do with what you have on hand.  I'm no exception.  In my 36 years as a licensed amateur radio operator, I've accumulated a wide collection of items, ranging from books to spare rigs.  Of course, the collection circulates a bit through trades, upgrades, giveaways to newly licensed hams, and, finally, to the recycling station.

One of the things I rarely sell or giveaway is my growing collection of books related to Amateur Radio and Amateur Radio antennas.  Many of these volumes were bought when I was newly licensed or successfully upgraded my license.  Nowadays, the task of assembling an Amateur Radio library is easier, thanks to the internet, Amateur Radio-related websites, and the outstanding …

A 40-10 Meter sloping Delta Loop Antenna. Post #238.

A one-wavelength loop is one of my favorite antennas.  Loops may be built in a square, circular, rectangular, of triangular form to create an effective, inexpensive antenna.  Loops can be built for single band service using coaxial cable and a quarter wave transformer or for multiple band use employing 450 ohm ladder line fed into a 4:1 balun and then into an antenna transmatch.  A small length of 50 ohm coaxial cable with UHF fittings can be used to connect your transceiver to the transmatch.

For my growing antenna farm at my new homesite in the Puna District of Hawaii Island, I needed an antenna which would give me good local coverage for local state wide nets and a decent signal for DX work.  From my location on Hawaii Island, almost anything beyond Hawaii counts as DX.  I elected to build a simple, one wavelength long sloping delta loop supported by a telescoping fiberglass mast and supported at the bottom ends by two wooden stakes.

In order to cover 40 through 10 meters, I desig…

A Multi-Band horizontal dipole. Post #237

How would you like to build a simple, inexpensive multiband antenna that will give you hours of enjoyment chasing DX or "ragchewing" with your local amateur radio friends?  Sometimes, when it comes to "homebrew" antennas, you can't beat a 40 through 10 meter dipole or doublet fed  by ladder line into a suitable antenna transmatch.  One antenna can perform well on a variety of amateur radio bands if it is designed and built carefully.

Ideally, we could all use a 50-foot (15.24 meter) tower with a 4-element monobander on 20 meters, plus separate antennas for 160, 80, 40, 15, 10, and whatever other bands you can squeeze in.  However, most of the amateur radio operators I know can manage only one or perhaps two HF antennas on their small properties.  Add to this mix the growing trend of antenna restrictions found in many housing areas these days and you've got the one antenna scenario.  And that antenna must be hidden in many cases.

Enter the horizontal flat t…