Simple Antennas for Amateur Radio Operators–a basic 10-meter dipole, post 207


HOW TO BUILD A BASIC 10-METER HAM RADIO ANTENNA

Amateur Radio is a great hobby, and building your own antennas has been one of the most popular aspects of ham radio. Listed below is a simple list of materials and construction techniques that can get a licensed amateur radio operator on the frequencies between 28.300 Mhz to 28.500 Mhz in the 10-meter band.

Construction details are based on an article by Billy Brainard, a contributor to eHow. You can find specifics by visiting http://www.ehow.com/print/how_5632754_build-ham-radio-antenna.html.

MATERIALS REQUIRED:
50 Ohm coaxial cable (RG-58, RG-8X, RG-8, or anyother 50 Ohm coax you have on hand); utility knife; wire cutter; wire strippers; a piece of plexiglass, 2 x2x 1/2 inches; soldering gun/solder; eye protection (glasses); 20 feet of insulated wire (#14 gauge); hand saw; drill and 1/2-inch drill bit; antenna mast (if desired).

ASSEMBLY INSTRUCTIONS:

Cut the plexiglass into three pieces–two at 2 x 3 inches, and one in the shape of a “T”. The “T” will be three inches across, the bottom will be four inches long. The width of both the cross bar and bottom piece will be two inches.

Cut two pieces of #12 gauge wire, each 8-feet, 6-inches long. These wires will form the dipole.

Strip off about once inch of insulation off one end of earch wire using a wire stripper.

Take the T-shaped plexiglass and drill a half-inch hole in each end of the top cross section and one in the bottom of the T about one inch from the edges.

Take the two wires at the end that has been stripped and run one each through the holes on the cross bar section of the plexiglass T. Run about three inches of wire through the hole and then back through the hole a second time so each wire is wrapped around one end of the cross bar of the T.

Take the two other cut pieces of plexiglass and drill a hole in each end about 1 inch from the edge. These two pieces of plexiglass will be the end insulators for the dipole.

Take the coax cable and measure about two inches from the end. Using your utility knife, cut down into the shielding slowly until you hit the wire mesh. Roll the cable with the knife until the cut goes around and back to the starting point. Cut away the shielding.

Pull back the wire mesh and twist it in a clockwise manner to tighten up the loose strands.

Now, using your utility knife, cut away the center plastic insulator (white), about a half-inch to reveal the center pin.

Using your soldering gun or iron, solder the center pin to the wire on one side ot the T. Solder the wire mesh to the other wire on the T. Your coaxial cable is now connected to the dipole antenna.

Mount the coax cable securely to the bottom of the T insulator using a small piece of rope and running it through the drilled hole and around the cable, tying it in a firm knot.

Using the rope, mount the top of the antenna as high as possible to a nearby antenna mast or tree away from an buildings.

Stretch out the ends of the dipole antenna. Using the rope connected to the end insulators drilled holes, mount them to a tree or pole so that the dipole wires make a slight downward slope and the antenna forms a slight inverted V shape.

Run your coax to an antenna tuner and then to your rig. Test your transmitter with a dummy load before you send that first “cq”. Be sure your antenna is clear of power lines or other obstructions.

This antenna is simple, effective, and inexpensive. I’ve built several inverted V dipoles
for the 40, 20, 15, and 10-meter bands. All of them show minimal swr for the intended band and will give you hours of fun at minimal cost.

OTHER IDEAS:

There are several good antenna ideas in the eHow reference library. These include:

How to PreTune a Ham Radio Antenna
How to Build 6 Meter J-Pole Antennas
Homemade 10-meter Antennas

These articles are well-written, concise, and easy to follow.

Good luck on your next antenna!

Until next time,
Aloha es 73 de KH6JRM–BK2915jx–along the beautiful Hamakua Coast of Hawaii Island.

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Simple Antennas for Amateur Radio Operators, dummy load antenna, post #206


A dummy load antenna

 

Have you ever tuned up your transceiver into a dummy load and gotten a reply to your test cq?  I’ve had that experience a few times, usually getting a reply from a nearby amateur who picked up the test transmission as I was fine tuning a rig.  The signals were never very strong, but they were there.  I suppose this type of contact happens with some homebrew dummy loads, such as lightbulbs and quickly assembled resistor loads placed in a metal container filled with mineral oil.

What if your dummy load could be used as part of an emergency antenna system?  I decided to test this idea over the past weekend and was mildly surprised how well it worked.

For the test, I used my 40 meter inverted vee in the backyard, 50-feet of RG-6 coax (with UHF adapters), a UHF “T” connector, my trusty Heathkit Cantenna, and the old Swan 100 MX.

I attached the Cantenna to one end of the “T” connector, the antenna coax to another end of the “T” connector, and ran a coax patch cord from the third end of the “T” connector to the Swan 100 MX.  The Drake MN-4 ATU was removed from the system.

The transceiver was pre-tuned on the dummy load before I disconnected the Drake MN-4 ATU.  I would run the Swan 100 MX at 10 watts to reduce possible rfi from this experiment.

The test worked very well with several local contacts (in Hawaii) reporting 539 to 549 signals on 40 meters from my qth along the Hamakua Coast of Hawaii Island.  Results on 15 meters were about the same.  The signals were about half as strong as I usually get from my inverted vee running at 10 watts.  Nothing spectacular to be sure.  The efficiency of this quickly assembled antenna system was probably dismal, but it did get me on the air with a usable signal.

The rig ran smoothly with no over heating, and signal reports were clean with no distortion.  After the test, I disconnected the UHF “T” and returned the antenna system to its regular configuration.  While I can’t recommend this antenna as a permanent fixture in the shack, it could be used in situations where there is no antenna tuner or you are forced to use a random length of wire for an emergency antenna.

With all of this in mind, I’ll be extra cautious when I tune the old Swan 100 MX into the Heathkit Cantenna.  Who knows what kind of DX awaits in the early hours just before dawn?  Maybe the Cantenna isn’t so “dumb” afterall.

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Until next time,

Aloha es 73 de KH6JRM–BK29jx15–along the beautiful Hamakua Coast of Hawaii Island.

 

Simple Antennas for Amateur Radio Operators–stealth antenna ideas, post #205


Stealth antennas that can keep you on the air.

Amateur radio operators are facing increasing antenna challenges from apartment-living lifestyles and the restrictions of community regulations and homeowners’ associations.  I’ve travelled that route myself, and getting a reasonably effective antenna erected in these situations can be a trying experience.  But once you master some basic principles of stealth or hidden antennas, you can get on the air.  A little creativity and ingenuity in the type of materials used and the location of your “antenna farm” can keep your love of ham radio alive.  Although a hidden antenna will not have exceptional performance, you will make contacts.

With this in mind, my weekly review of antenna literature often turns up a few nuggets among the advertised hype found in amateur radio publications.  Among my favorite morale boosters is Zachary Fruhling, KD6DXA, of Santa Cruz, California.    Like many of us, he is an apartment dweller and has to use a variety of stealth antenna ideas pursue his amateur radio hobby.

A few months ago, I bookmarked one of his articles that seems to encapsulate most of the ideas surrounding hidden antennas.  You can find “Stealth Ham Radio Antennas:  A How-To Guide” by checking http://voices.yahoo.com/stealth-ham-radio-antennas-guide-2032424.html.

Briefly, Zachary outlines the various types of stealth antennas that he has found useful and some of the precautions needed to get this antenna working.

1.  Zachary stresses the importance of having a properly operating radio station if you want to use a stealth antenna.  He says “stealth antennas are notoriously susceptible to causing interference, especially if your station is not operating 100% properly.  That means you should be using a low-pass filter at your transmitter’s output to eliminate unwanted harmonics…you may also need an antenna tuner to ensure that your crafty yet stealthy antenna is properly matched to the impedence of your transmitter’s output.”  You should also have dummy load to tune up your transmitter off the air.

2.  Successful stealth antennas will usually be wire antennas “due to the ability to hide the antenna with thin gauge wire.”  Zachary notes that “it is possible to construct a dipole antenna or a random wire antenna using extremely thin magnet wire or bus wire, the only concern of which is the mechanical strength of the wire to support its own weight and that of the antenna feed line.”  Zachary says a random wire can be of any length, being as long and as high as possible.

3.  Another stealth antenna design is to use a flagpole vertical antenna made of pvc pipe or a conductive copper or aluminum pole.  Several commercial antenna flagpole antennas are available.  Or, you can insert the radiating element into the PVC pipe and use the pipe to fly the colors.  Unless your HOA disapproves of a flagpole, this type of antenna will generally be accepted by the neighbors and will “write it off as the byproduct of an eccentric bricoleur.”  As is the case with compromise antennas, you should not expect stellar performance from these antennas, but they will get you on your favorite bands, “which is the most important thing.”

4.  In an absolute “no antenna” environment, you could always erect a random length wire inside your apartment or home.  In fact, says Zachary, “I currently use a 50′ length of bare bus wire, strung around the perimeter of my apartment’s ceiling as my main stealth ham radio antenna…it is about as minimalist as a stealth antenna can be, but I am on the air despite my difficult landlord situation.”  Although my restrictions are not as severe as Zachary’s, I have a backup, emergency “long wire” (66-feet) tacked to the ceiling of my rental home.  The wire snakes around the kitchen, hall, and the bedrooms.  With a good counterpoise attached to the trusty Drake MN-4 ATU, I can make contacts at 10 watts or less without upsetting any electronics in the house.  Of course, I do better when propagation is good.

5.  Although KD6DXA doesn’t break any new ground in his article, his enthusiasm is contagious.  He says “you may not have the loudest signal on the block, but you will be heard, especially if you use a high-efficiency mode such as CW or any of the various digital modes which are well-suited to low-power and weak-signal work.”  He concludes his essay by saying “no idea is too crazy, and even the worst possible antenna will get some signal out; just load it up to an antenna tuner and you will be back on the airwaves in not time.”

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Until next time, thanks for joining us!

Aloha es 73 de KH6JRM–BK29jx15–along the beautiful Hamakua Coast of the Big Island of Hawaii

Simple Antennas for Amateur Radio Operators–Wooden Fence Antenna, post #204


The Wooden Fence Antenna

How would you build a hidden antenna if all you had in your back yard was a 6-foot high wooden fence?  That question was posed by Rick Todd (no amateur radio call given) in a request first posted at antennas@qth.net. list, January 1999.  John Matz (no amateur call given) responded with a brief, but thorough explanation that may help you build an antenna where there was no place before.

In his reponse, Matz said the 6-foot high fence would supply basic support for a simple, yet effective antenna.

Matz listed several steps to make this antenna:

1.  Get a good antenna tuner and “learn how to use it.”

2.  Get some insulated house wire and an eight-foot ground rod.

3.  Sink the ground rod near the fence.  Matz says the ground rod will serve as your coax ground.

4.  Tack up a number of 1/4 wave elements (234/f in feet), separated, up on the fence.  He suggests using 8-feet for 10 meters, 16-feet for 20 meters, etc., “all in parallel to the center conductor of your coax.  Matz says “they don’t have to be straight…just 6-feet up, and then over horizontally..or slanted at a 45 degree (angle), and then bent over.  Keep as much of the wire as high as possible.”

5.  Use the tuner in your shack to lower swr.

Matz claims this very basic antenna can be used as low as 75 meters, admitting that “it’s not as efficient as some antenna systems, but it’s cheap.”

When I lived in Honokaa back in the mid-70s, a backyard fence was configured like the description above and it worked fairly well on 40, 15, and 10 meters (I was a novice class opertor at the time).  The only improvement to the above design was the addition of 8 quarter-wave radials for 40 meters to the ground road.  The efficiency was probably pretty bad, but I did manage to get several hundred contacts on the fence antenna and about 100 or so contacts on a homebrew inverted v.

You may want to adapt Matz’s idea if there is no other way to get a stealth antenna outdoors.  The idea is to get on the air, despite the limitations of your living conditions.  You can find the complete article by visiting http://www.hard-core-dx.com/nordicdx/antenna/hidden/fence.html.

You can follow our blog community by subscribing to our free email notification service.  You can also tap into the blog RSS feed.

Until next time,

Aloha es 73 de KH6JRM–BK29jx15–along the beautiful Hamakua Coast of Hawaii Island.

Simple Antennas for Amateur Radio Operators–a 10 meter dipole for the attic, post #203


A simple 10 meter dipole for your attic.

As mentioned in several posts, many amateur radio operators are faced with restrictive covenants that limit their radio activities.  Such restrictions include lack of outdoor space, CC&Rs, HOAs, and municipal limitations on towers.  While these challenges are often formitable, a little creativity and stealth can still put you on the air.  Granted that hidden antennas will never overpower hams with beams, linear amplifiers, and tall towers, a well-designed apartment or attic antenna can still give a good account of itself.

A few days ago, I ran across an interesting antenna site called “Clif’s Ham Radio page” (http://members.tripod.com/~Pilot_Clif/HAM-HOME.HTM).  Although I was unable to determine Clif’s callsign, the information in his two-page article seems to be “spot on” for those of us plagued with antenna limitations.

Among the antennas discussed was a simple 10 meter dipole in Clif’s attic, which produced acceptable results without the neighborhood getting concerned about a ham in its area.  Over the years, it’s become fashionable to blame hams for any rfi people experience from poorly filtered consumer electronics.  So, by keeping your antenna out of sight, running digital modes, and using power below 100 watts, you may be removed from what is often called the “housing police.”

Anyway, Clif made a full-sized 10 meter dipole (a total of approximately 17-feet) using #24 gauge magnet wire and ceramic insulators.  Clif oriented the antenna in a general north by northwest by south southeast direction.  The dipole was erected in the attic of his two and a half-story Southern California  condominium unit, with the shack located in the upper level and the antenna mounted in the attic using cord to hold the dipole between the rafters.  Cliff estimates the actual height above ground was between 25 and 30 feet.

The rig used was an Icom IC-725 running around 50 watts coupled to the antenna with RG-58U coaxial cable.  He used a MFJ-941E for his ATU.

According to Clif, when the 10 meter band was open, he received signal reports ranging from 55 to 59 (SSB).  He adds that “contacts were made to Indiana, Alabama, Louisiana, Texas, Wisconsin, Kansas, Minnesota, Mississippi, Pennslyvania, North Carolina, New York, Rhode Island, Hawaii {my QTH} plus a few other states and even Japan!”

Clif admits that the favorable results were helped by the building’s wooden structure and the more than half-wavelength elevation of the attic dipole.  Clif concludes that “the contacts appeared consistent with the orientation of the antenna, that is most of the contact (s) occured broadside to the antenna.”

Clif also describes a few other disguised amateur radio antennas, including a 40 meter twin lead attic Marconi, a triband inverted V dipole under the eaves of a house, and another attic mounted 10 meter antenna.

Hopefully, Clif’s ideas can help you get on the air.  The cost of these disguised antennas should be minimal, depending on what you already have on hand.  There’s no reason to be off the air.

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Until next time,

Aloha es 73 de KH6JRM–BK29jx15–along the beautiful Hamakua Coast of the Big Island of Hawaii.

Simple antennas for Amateur Radio Operators–a 6/2 meter quickie dipole, post #202


A simple 6 and 2 meter dipole.

How would you like to build a simple, inexpensive two-band dipole that will get you on both 6 and 2 meters?  Steve Ford, WB8IMY, the Editor of “QST“, faced such a problem when he had to build such an antenna for Field Day.  The antenna is fairly simple to make and, according to Steve, should take you about a half-hour to complete.  Ford describes the “6 + 2 = 1” antenna on page 49 of the October 2012 issue of QST.  He has included a basic diagram and a photograph of the completed project in the article.

Ford approached his emergency antenna with a few references to “QST’s” Technical Editor Joel Hallas, W1ZR, who was making HF antennas using the “venerable skeleton sleeve antenna to create some nifty dual band HF dipoles that anyone could put together with minimal effort.”  You can find these exploratory articles in the May 2011 and October 2011 issues of “QST”.

Basically Ford needed to build a quick-to-construct 6 and 2 meter combo antenna “that I could feed with a single coaxial line–anything simple and omnidirectional would do.”  He rescaled the original HF design to accommodate the 6 and 2 meter bands.

Materials needed:

According to Ford, all that was needed was approximately 110 inches of 450-ohm ladder line, an SO-239 or Type N connector and a convenient lenght of coaxial cable.

First, Ford cut a length of transmission line to around 109 inches, giving about 3 inches at each end to wrap into the insulators.

Second, Ford attached the appropriate connector to the exact center of the ladder line.

Then, he made two cuts in the wire opposite the one he had chosen for the connector.  He then made one cut of 17 3/4  inches to left of center and another 17 3/4 inches to the right for 35 inches total length.  According to Ford this arrangement “creates the coupled resonnator 2 meter element.

Fourth, he used a sharp box cutter ” to carefully slice through the plastic insulation that separtes the two wires, working from the ends back toward center an stopping as you reach the cuts in the 2 meter wire…throw away this unneeded insulation and wire.  Your goal is to end up with the 2 meter element uniformly separated from the 6 meter wire and supported by the remaining insulation.”

How well does this antenna work?  According to Steve Ford, his antenna analyzer showed SWR on 6 meters was well below 2:1 from 50 to 52 MHz.  On the 2 meter band, “I enjoyed an SWR below 2:1 across the entire band.  No need to trim the antenna at all.

Ford goes on to say, the emergency antenna worked very well despite its low height above ground.  He does recommend, however, that you hang the dipole vertically with the coaxial feed line “running perpendicular to the antenna for at least 5 feet” if you will be using FM in these bands.  Ford adds that “vertical polarization is the custom for FM and VHF frequencies and being in sync with your fellow hams makes a big difference in signal strength at both ends.”

Ford concludes his article by saying he simply “packed it (antenna) away in a small box for future use…for sheer flexibility and ease of assembly, this little VHF dipole is indeed a miracle.”

So, there you have another simple antenna idea that could work in a restricted space environment.  This antenna could be used as well on HF frequencies by referring to the the May 2011 and October 2011 “QST” articles.  I guess it’s time to warm up the soldering gun and get something new in the air.

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Thank you for joining us today!

Aloha es 73 de KH6JRM–BK29jx15–along the beautiful Hamakua Coast.

Simple Antennas for the Amateur Radio Operator–a basic vertical, post #201


A simple 40/15 meter vertical for your backyard.

For those of us confined to limited real estate, a basic 40/15 meter vertical erected in your backyard may be the answer to your antenna woes.  Granted, a vertical is sometimes derided as an “antenna that radiates poorly in all directions,” but, with a decent radial or counterpoise system, that simple 33-foot wire taped to a fiberglass or pvc mast can deliver hours of fun at minimal expense.

Like many of you, I have a postage stamp sized back yard that can’t support a full-size dipole, but can accommodate a simple vertical and a modest radial field.  Here are the materials you’ll need to begin the antenna process:

1.  A 32 to 33-foot mast–pvc, fiberglass, or even a long fishing pole.

2.  A 33-foot piece of #14 through #22 gauge wire.  The heavier gauge wire will withstand the weather a bit better than its thinner cousins.  Use what you have on hand.  Even unused speaker wire or lamp zip cord can be used.

3.  Enough wire for 6 to 10 radials, each wire being approximately 33-feet.  You may have to look around for this much wire. Or, you can buy some wire from the nearest hardware store or Radio Shack outlet.  Ideally, your radial field could have as many as 60 to 120 radial wires, but that may be overkill.  From what I’ve read, 30 to 60 radials will provide an excellent radial system for your station.  I chose 6 to 10 radials, because that’s what I can fit in my backyard.  Even this small number of wires can improve the efficiency of your vertical antenna.

4.  Enough coaxial cable to reach your station.  If you operate below 100 watts, RG-58, RG-8X, or even RG-6 (with proper UHF connectors) can be used.  RG-6 is rated at a nominal 75-ohms, but it can be used with a tuner to smooth out the small mismatch between your 50-ohm rig and the antenna.   If you plan to run higher power (over 100 watts), use heftier cable such as RG-8 or RG-213.

 

5.  An exposed ground stake and swivel mount to support your mast.  DX Engineering sells a swivel mount that can accommodate a variety of commercial and homebrewed vertical antennas.  A  swivel mount is handy for raising and lowering the vertical antenna when you aren’t using it.

6.  Rope or nylon guy lines to support the mast.

7.  An automatic or manual antenna tuner to reduce swr and provide coverage in the 15 meter band.  A 40 meter vertical will provide passable operation on 15 meters by using the third harmonic of the chosen 40 meter frequency.  There will be a slight mismatch because the third harmonic of some 40 meter frequencies will be out of the 15 meter amateur band.  Your antenna tuner can help keep the mismatch to a low level.

8.  Connect your coax to the antenna, attach your radials (as many as you can get in your small space), run the coax to your tuner, tune up your rig into a dummy load, and get set to get on the air.  While this arrangement won’t rival a beam on a 50-foot tower, your homebrew vertical will get you on the air.

If you want multiband performance from your 40 meter vertical, use 300-ohm tv twin lead or 450-ohm ladder line as your feed line.  Run this feed into a 4:1 balun; run coax from the balun to your tuner; run a short piece of coax from your tuner to your rig.  Tune up on a dummy load and then switch over to “live.”

If for some reason, an extensive radial field is not possible, try using a tuned counterpoise for the lowest frequency you plan to use.  My current 40 meter vertical is using a counterpoise and it seems to work well.  The Drake MN-4 ATU in the shack handles the swr without a problem and the old Swan 100-MX runs cool.

So, if you have a bit of room in the backyard, why not put up a 40/15 meter vertical?  You may be surprised just how good it works.  Although I’ve used indoor antennas with some success, an outdoor antenna will get you more contacts and will reduce rfi problems often found with interior antennas.  And best of all, these homebrew verticals are fairly cheap, easy to build, and can be lowered out of sight when your operating day is done.

You can follow this antenna blog by subscribing to our free email subscription service or by tapping into the blog RSS feed.

Until next time,

Aloha es 73 de KH6JRM–BK29jx15–along the beautiful Hamakua Coast on the Big Island of Hawaii

 

 

 

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