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Showing posts from October, 2013

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…

A 30 Meter Sloping Dipole Antenna. Post #236

The 30 Meter Amateur Radio band (10.100 MHz to 10.150 MHz) is territory for the cw and digital enthusiast.  You can find cw operators around 10.105 MHz and many Japanese hams clustering around 10.130 MHz.  In between, you'll find RTTY, PSK 31, FAX, and other digital modes.  If you're a cw operator, 30 Meters can be the place to make new friendships at a leisurely pace while increasing your sending and receiving skills.

Antennas for this tiny sliver of the rf spectrum are modest and inexpensive to build with many materials obtainable from the nearest home improvement outlet or hardware store.

Over the past few weeks, I've built several 30 Meter antennas for my new house lot in the Puna District, including an inverted vee, a ground plane, a delta loop, and even an inverted "L".  All have worked well.

The latest addition to my growing antenna farm is a 30 Meter halfwavelength sloping dipole.  This variation of the basic horizontal, halfwavelength flat top dipole ha…

A modified 30 Meter Ground Plane Antenna. Post #235.

This week, I'm exploring the joys of 30 meters and the antennas that support this intriguing amateur radio band.

Last week, I built a simple 30 meter inverted vee antenna which continues to deliver outstanding performance.

Today, I decided to try a 30 meter ground plane antenna, consisting of a main vertical element and four sloping radials.  Many antenna experts believe that sloping the radial elements by 45 degrees will produce a better match for 50 ohm coaxial cable feed lines. Although my sloping radials don't come off the connector at 45 degrees,  they do seem to produce a usable match for my RG-8X feedline.  Any mismatch is corrected by my standby antenna transmatch--an old MFJ-941 E Versa Tuner.

According to "searchmobilecomputing.tectarget.com", a ground plane "is a variant of the dipole antenna designed for use with an unbalanced feed line such as coaxial cable.  It resembles a coaxial antenna whose lower section consists of straight elements called ra…

A 30 Meter Inverted Vee Antenna. Post #234

The Thirty meter amateur radio band extends from 10.100 MHz to 10.150 MHz.  This sliver of the rf spectrum offers plenty of space for the die-hard cw fan as well as plenty of contacts for those into the various digital modes.  The operators who populate this band are generally friendly and willing to help out those unsure of the digital frontier.  You'll find plenty of action with PSK31 and RTTY as well.  Antennas for this band are simple and inexpensive.  While thirty meters is a good night time DX band, there are some interesting day time opportunities as well, especially towards sunset.  Besides, a few hours on thirty meters will give you some new contacts and an opportunity to improve your cw speed.

So, let's build a simple antenna for this band.  I built an inverted vee for thirty meters last weekend after I finished clearing some brush from my new home site in the Puna District.  I chose the inverted vee option because I had a spare fiberglass mast in my garage and didn…

The K3MT "Grasswire Antenna". Post #233

How would you like to use what I call the "ultimate stealth antenna" at your deed-restricted location?  While I was doing some research for antennas at my new home location in the Puna District of Hawaii Island, I came across a fascinating article by Mike Toia (K3MT).  Over 20 years ago, Mike designed, built, and used something called the "grasswire antenna" which would serve as a  nearly invisible, yet effective antenna while he traveled from his various jobs.  Although the antenna appears to be a lossy dummy load on steroids, the data revealed by Mike show that this unusual antenna does work--not as well a dipole or a yagi, but it does get contacts in difficult operating situations.

The antenna is ridiculously simple to build and use.  Mike says his design "is an end-fed, longwire antenna that is laid right in the grass."  This would be perfect for those amateurs that have restrictive HOAs and CC&Rs prohibiting outdoor antennas.

Mike's original…

A simple, portable 40-10 meter vertical antenna with counterpoise. Post #232

How would you like to build a 40-10 meter vertical antenna that could be used in portable or emergency situations?  For the relatively low cost of some housewire, a length of 450-ohm ladder line, some clip leads, a few insulators, a 4:1 balun, a small length of coaxial cable, and an antenna transmatch, you could have a simple multiband antenna that will give you hours of fun on your next mini DXpedition to the nearest public park or in your own back yard.  With a  QRP rig, a deep cycle marine battery, and a few solar panels, you can enjoy a few carefree hours without increasing your electric bill.
I have such a station placed in my Odyssey van.  I can operate when the mood strikes me or when a local emergency is declared.  During the quarterly break from my teaching duties, I decided to unpack my portable station and give it a brief "shakedown cruise" at my new homesite in the Puna District of Hawaii Island.
I wanted to relax a bit after a day's work of clearing the lan…

A radiating dummy load antenna, part 2. Post #231

In my last post, I recounted a conversation I had with Dean Manley (KH6B) on Monday, 30 September 2013 concerning the use of "dummy loads" as emergency antennas.  The conversation centered around Hank Scharfe's (W6SKC/7) attempt to get some power into his 150-ft (45.73 meters) grounded inverted "L" antenna following the failure of his automatic antenna tuner.  Hank was successful in meeting his scheduled nets when he used his Waters dummy load with a "T" UHF connector to feed some rf to his antenna.  Although most of his power was confined to the dummy load, there was sufficient power delivered to his antenna to complete his schedules.

Dean and I have made several such antennas for field day and portable operations.  In fact, I mentioned my own experience with a dummy load antenna back in September 2012 when I was a newly licensed novice operator.  That contact surprised me, and that experience has kept me interested in radiating dummy loads ever sin…

The radiating dummy load. Post #230

On Monday, 30 September 2013, I had the day off from my substitute teaching assignment and I decided to meet with some of my amateur radio friends at the Hilo, Hawaii Jack In The Box Restaurant for informal discussions concerning amateur radio.  The Hawaii QRP Club holds daily meetings at the popular fast food restaurant around 0800 W.  Most of the time, the meetings are concerned with the usual topics of rigs, DX, antennas, and the latest HOA restrictions on ham operators.  Monday's meeting was going to be different.

By the time I arrived at 0800 W, most of the group had departed for their jobs and other concerns, leaving only myself, my xyl, and informal club president Dean Manley (KH6B) left to "hold the fort."  Several times in the past I had lamented my fate in using compromise antennas in the various homes I rented while I was fully employed as a news announcer for KKGB-FM and KHLO-AM in Hilo.  Now that I was building a new home on a larger property, I had more sp…