Skip to main content

Simple Ham Radio Antennas: The 10 meter 1/2 wavelength sloper. Post #262

The sloping 1/2 wavelength dipole is one of my favorite antennas.  "Slopers" are good antennas for restricted space areas.  They are simple to build, inexpensive, and exhibit some directivity in the your chosen direction.

According to VK6YSF, VE2DPE, and other amateur radio operators, a properly designed 1/2 wavelength sloper radiates energy at low angles relative to the horizon with vertical polarization.  Slopers don't require a ground radial system and can be fed with a good grade of 50 ohm coaxial cable.  A sloper antenna only requires one tall support (tree, mast, edge of a roof, etc.) and occupies less space that a 1/2 wavelength horizontal dipole.

So, let's build one of these simple, effective antennas for the 10 meter band, centering on 28.4 MHz--right in the middle of the techncian class phone band.

MATERIALS:

One tall support.  In my case, I used a 33-ft/10.06 meter MFJ telescoping fiberglass mast..

One 5-ft/1.52 meter wooden stake to support the fiberglass mast.

One 6-ft/1.82 meter wood stake to tie off the sloper.

Two ceramic insulators, one for the upper portion of the sloper and the other for the bottom portion of the sloper.

One coaxial cable center connector.  I had a spare Budwig HQ-1 center connector in the junk box.  You could also make a center connector from wood, plastic,or another ceramic insulator.

Fifty feet/15.24 meters of RG-8X coaxial cable with UHF connectors.

Basic tools, including a soldering gun/iron, pliers, wire cutters, vinyl electrical tape.

A length of #14 AWG house wire for the two antenna elements.  Using the general dipole formula of 468/f (MHz)=L(ft) and a working frequency of 28.4 MHz, I cut a piece of wire measuring 16.47 ft/5.02 meters.
This length was cut in half to get each dipole segment.  Each segment then measured 8.23 ft/2.51 meters.

Several 3-ft/0.91 pieces of RG-8X coaxial cable to interconnect shack equipment (rig, low pass filter, dummy load) to the Drake MN-4 antenna transmatch.

Fifty-feet/15.24 meters of dacron rope to tie off the sloper to a nearby wooden stake.  I wouldn't need all of the rope for this antenna, but I decided to use what I needed and coiled up the rest  for use in future sloper antenna projects.



ASSEMBLY:

The antenna was made in the garage and then taken outside to be strung from the fiberglass mast.  Prior to making the antenna, the fiberglass mast was positioned on the ground.

I attached a ceramic insulator to each segment.  The insulator on the lower element would be attached to the wooden support stake by dacron rope.  As mentioned above, the rope length would be kept intact for other sloper projects.

I attached the upper segment of the sloper element to the + side of the Budwig center connector and attached the lower segment to the - side of the Budwig center connector.  All connections were soldered and wrapped with several layers of vinyl electrical tape.

Before I attached the RG-8X coaxial cable, I wound a "choke balun" consisting of 6 turns of the cable measuring approximately 8 inches/20.32 cm in diameter.  The balun was secured by vinyl electrical tape.  I then attached the RG-8X coaxial cable to the center coax connector.  After that, I attached the upper end of the top segment to a ceramic insulator.

Once outside, I attached the upper ceramic insulator to the top of the mast with short pieces of dacron rope.
I then tied some dacron rope to the ceramic insulator at the bottom of the lower antenna segment.

I slowly raised the mast and slipped it over the wooden support stake.

The lower end of the sloper was tied to a 5-ft/1.52 meter wooden stake approximately 30 ft/9.14 meters from the base of the mast.  The RG-8X feed line was run from the sloper at a right angle and secured to the base of the fiberglass mast with nylon ties.

I ran the RG-8X coaxial cable through the shack window and into the Drake MN-4 antenna transmatch. The Ten-Tec Argosy II transceiver, a low pass filter, and the old Heathkit Dummy Load were connected to the transmatch by short pieces of RG-8X patch cable.

INITIAL RESULTS:

Without the Drake MN-4 in the system, the swr measured 1.6 to 1 between 28.3 MHz and 28.5 MHz. With the transmatch in the system, I was able to get a swr of 1.1 to 1 on those frequencies. I was also able to use the lower portion of the band for cw if I adjusted the Drake MN-4 to compensate for the small mismatch between the transceiver and the antenna.

Although 10 meters is a bit uncertain at times, I was able to get some excellent contacts in California, Oregon, and Washington State on 28.4 MHz between 1100 to 1600 local time (2100 to 0200 UTC).  My ssb reports ranged from 53 to 57.  Not terribly outstanding, but usable.  I didn't note much directivity in the antenna when I shifted position of the sloper by moving the wooden support stake.  I may have gained a single "s" unit when I pointed the sloper toward the U.S. mainland.

This was a fun project.

REFERENCES:

http://www.dxzone.com/catalog/Antennas/sloper/.

http://www.dxzone/cgi-bin/dir/jump2.cgi?ID=27575.

ARRL Antenna Book, 18th Edition.

http://hamradiosecrets.com/ham-radio-hf-antenna.html..

Thanks for joining us today!.  You can follow our blog community with a free email subscription or by tapping into the blog RSS feed.

Aloha de Russ (KH6JRM).
BK29jx15--along the beautiful Hamakua Coast of Hawaii Island.
Enhanced by Zemanta

Comments

Popular posts from this blog

G5RV Multi Band HF Dipole Antenna. Post #1555.

If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=aeNHIQ_j4Dk

This well-produced and richly illustrated tutorial on the classic G5RV HF Dipole Antenna was presented to the Brandon Amateur Radio Society in Brandon, Florida in 2017 by Bernie Huth (W4BGH).  Bernie does an excellent job of  explaining the pros and cons of this popular HF antenna from the late Louis Varney (G5RV).  Although Varney envisioned his design primarily as a 3/2 wavelength antenna for the 20 meter Amateur Radio band, radio amateurs have used the antenna for multiband use.  The G5RV is an excellent choice for the 20 meter band.  Performance on other HF Amateur Radio bands is good enough to qualify as stand alone HF antenna if you can only erect one HF antenna.

For the latest Amateur/Ham Radio news and information, please visit these websites:

http://www.HawaiiARRL.info.
http://www.arrl.org.
http://www.arrl.org/arrl-audio-news (a weekly podca…

Amateur Radio Bicycle Mobile Setup. Post #1554.

If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=2zWb-KnkGdY.

Here's a way to use Amatuer/Ham Radio while you work on shedding a few pounds in useful exercise.  Why not equip your bicycle for 2 meter/70 cm mobile operation?

In this short, well-made video, "taverned" shows us how he used a mag mount antenna, a simple C clamp, and a basic ground system to convert his mountain bike into a mobile station.  The project is straight forward, simple, and gives you emergency communications while you peddle down the road.

For the latest Amateur/Ham Radio news and information, please visit these websites:

http://www.HawaiiARRL.info.
http://www.arrl.org.
http://www.arrl.org/arrl-audio-news (a weekly podcast which is updated each Friday afternoon).
https://hamradiohawaii.wordpress.com.
https://bigislandarrlnews.com.
https://amateurradionewsinformation.com (Amateur Radio News & Information).
https://www.eha…

An 80-Meter Vertical Helix

Like many amateur radio operators, I live on a small lot surrounded by neighbors, utility lines, and civic-minded citizens concerned about the "attractiveness" of my community.  Whether by design or outright fear, I've adopted the "stealth" approach to ham radio antennas.  It's the old "out of sight, out of mind" idea applied to amateur radio antennas.

The amateur radio press is full of articles describing the struggle of amateur radio operators to pursue their hobby under the burdensome regulations of CC & Rs, HOAs, and other civic minded citizens who object to antenna farms.  So far, my modest verticals, loops, and inverted vees have blended well with the vegetation and trees bordering my small backyard.  Vertical antennas have always been a problem because of the limited space for a radial system.  There are times, however, where a shortened vertical for the lower HF bands (such as 80/75 meters) is necessary where horizontal space is lacki…