Simple Antennas for Amateur Radio Operators–a continuing series


A Simple 40, 20, 15, and 10 meter vertical for your backyard.

Post #190

 

How would you like to build a simple multiband vertical in your backyard that will give you hours of fun at minimal cost?  You may already have most of the materials around your house.  Or you can buy the materials at a modest cost from your nearest home improvement or hardware store.

Here is a list of materials I used to build this vertical for the Hawaii QSO Party:

A 33-foot mast, either fabricated from schedule 40 pvc pipe or bought from MFJ Enterprises or Jackite.  I had an old MFJ fiberglass mast stored in the garage, so I used it to support the vertical elements of the antenna.

Approximately 150-feet of #22 gauge hookup wire.  You can use whatever wire you have in your junk box.  You can buy wire in various gauges from Radio Shack, Home Depot, Ace Hardware, or from your neighborhood hardware store.  The wire will be used for radiating elements as well as a counterpoise wire for 40, 20, 15, and 10 meters.

Fifty feet of RG-8 coaxial cable.  For this low power project, any coax you have stored in your shack can be used.  I’ve used RG-6, RG-8X, and even RG-58, depending on what I could find in my collection of spare parts.  Fortunately, the coax in my supply has UHF connectors which will make things a lot easier when it comes to connecting your equipment.

A dipole connector such as the HI-QUE connector (available from Fair Radio Sales in Lima, Ohia).

A 1:1 balun to keep rf off the shield of the coax.  Also, you could make a choke balun out of several turns of your coax feed.

An antenna tuner to minimize swr.

A low pass filter to reduce any TVI.

Procedure:

Lay your pvc pole or fiberglass mast on the ground.  Attach 33-feet of wire to the mast and secure with electrical tape.  This will be your 40 meter element.  Attach 16 feet, 6 inches of wire to the mast, beginning at the bottom and stretching to about mid-way up the mast.  This will be your 20 meter element.  Secure wire with tape.  Attach 11 feet of wire to the mast, beginning at the bottom and stretching up the pole.  This will be your 15 meter element.  Secure wire with tape.  You could eliminate this step, since the 40-meter element will be useable on its third harmonic for 15 meters.  However, I’ve found it best to attach a separate 15 meter wire to the mast.  Finally, add 8-feet, 3 inches of wire, beginning at the bottom of the mast and stretching it out along the pole.  This will be your 10 meter element. Secure with tape.

Now, measure out counterpoise wires of 33-feet, 16 feet, 6 inches, 11-feet, and 8-feet, 3 inches.  Attach the vertical elements to the postive extension of the HI-QUE dipole connector and attach the counterpoise wires to the negative extension of the HI-QUE connector.

Attach a set of three guy ropes or wires at the 15-foot level of the mast.

Next, drive a 5-foot wooden or steel fence post approximately 3-feet into the ground.  Slip the mast over the extended 2-foot stub and secure the guy wires or ropes to tie off points.  Run the counterpoise wires away from the vertical mast, so the antenna resembles a “L”.  Connect your coax and run the feedline to your rig.  This process can be made more secure against the elements by making a swivel arrangement at the mast stake.  DX Engineering sells a mast swivel device that is sturdy and can raise and lower your mast with little effort.

An even simpler arrangement would be to use one 33-foot vertical element and one 33-foot counterpoise wire fed with 300-ohm twinlead or 450-ohm ladder line.  This type of feedline, along with a 4:1 balun, and a short run of coax to your tuner will give you 40 to 10 meter coverage without the use of separate vertical elements.  I’ve used both arrangements with good results.  Of course, when I added more radials, antenna performance improved.  But, in my situation, the lack of adequate space in my backyard makes an extensive radial field nearlly impossible.  While performance of this antenna can not match that of a beam or a vertical with many radials, it does allow me to get on the air and grab contacts.  And when I’m done bouncing signals off the ionosphere, I can lower the antenna to ground level where neighbors can’t see it and where storms or lightning can damage it.

Have a good weekend!

Aloha es 73 de KH6JRM–BK29jx15

 

 

 

 

 

 

 

 

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