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Hamstick Dipole Fact Sheet

from Steve Cuccio, NB3O on November 9, 2001
View comments about this article!


Hamstick Dipole As A Practical and Portable Limited-Space HF Antenna

2001, Virginia RACES, Inc. - For Educational Use Only

Steve Cuccio, NB30, NM, Old Dominion Emergency Net

And Ed Harris, KE4SKY, VA State RACES Training Officer

When setting up portable or space restricted antennas, stand-alone mobile whips are often avoided due to the lack of a good grounding method. Stringing ground radials or using a ground rod in the field or the attic becomes increasingly difficult. While using one mobile whip by itself requires a good ground or counterpoise (usually the car body), a pair can be operated as a dipole. Lakeview (www.hamstick.com) makes a universal dipole mount for $13.95. They also supply quick-disconnect fittings with 3/8 X 24 threads which allow push-and-twist assembly of the mobile whips to the dipole mount within seconds for those of us wishing to make a quick setup or band change without tools.

Pro-Am makes Valor HF linear loaded whips that disassemble in half using a single threaded nut. This has the advantage that tuning adjustment is not lost when the antenna is disassembled. Hamstick whips have two small set screws that must be loosened to remove the stinger portion. Both brands cost about $24 per whip. The eight-foot whip disassembles to two four-foot pieces. Each whip is designed to cover one amateur band and can be adjusted from the phone to the CW sub-bands by changing the stinger length.

The 2:1 VSWR bandwidth is narrower on the lower bands since the whips are proportionally smaller compared to the longer electrical wavelengths. The 20-meter whips measured about 100 kHz, the 40-meter at 40 kHz and the 75-meter about 20 kHz. If your HF rig has a built-in tuner, the useable frequency span approximately doubles without significant loss of antenna efficiency.

An on-the-air comparison was made between the portable whip dipoles up 20 feet and half-wave dipoles for 40 and 75 meters. On 40 meters, two whips were about 1-1/2 S-units (about 10 dB) below the half-wave 40-meter dipole. Two 75-meter whips were almost three S-units (about 18 dB) below a half-wave 75-meter dipole (no wonder, since a 75-meter half wave dipole is 130 feet compared to the 16 feet of the two whips). On 20 meters, we were surprised to see only about one S-unit (6-dB) difference from a G5RV dipole antenna. Getting the portable whip dipole higher than 20 feet would also improve efficiency on the lower bands.

This portable dipole system was used to make contacts with European Russia on 20 meters from a condo in San Luis, CA as well as by Ed to San Juan Puerto Rico, Prince Edward Island and Mexico City from the Pentagon south parking lot in Washington, DC during the 2000 Marine Corps Marathon.

A pair of Radio Shack 10-foot TV mast sections supported my antenna parallel to the plastic rain gutter on the corner of the house. Bungee cords were used to hold it in place. Raising and lowering the antenna and masts to change bands can be done by one person, but two make the job easier when the wind is blowing.

Ed uses four 5-ft. mast sections for ease of storage in a vehicle. He recommends that whips all be equipped with quick-disconnects, be color-coded by band and stored with a 4' ground rod in capped 3" diameter PVC pipe. ARES / RACES may need to set up in a paved area such as an EOC parking lot. To do so bolt a folding 3-ft. TV roof tripod onto a triangular support frame constructed of three 5' pieces of 1" angle iron, using 1/4-20x3" bolts and wing nuts. Similarly attach a length of 2x6" across the open end opposite the TV tripod. Park a front tire of your vehicle on the board or place sandbags across it to provide wind stability. All stash easily in an SUV. With practice, you can erect the antenna in 5 minutes!

A variation provides dual HF band coverage with a single coaxial feedline. Two hamstick dipole mounts were bolted together with their center-isolated posts connected together using #12 gauge wire. Two sets of whips for 40 and 75 meters were assembled. Coax was attached to one of the mounts. There is minor interaction between the whips, although the #12 gauge wire looks slightly capacitive. Connecting the coax to the lower band dipole mount reduces the effect of the #12 gauge wire. A 25-foot length of coax was coiled at the base of the mast as an RF choke to reduce any stray RF from coupling onto the shield. The same could be accomplished by using ferrite beads on the coax feed near the dipole mount.

Either arrangement provides a viable, convenient, portable, horizontally polarized, high-angle antenna for NVIS operation on 40 and 75 meters. It is also a directional antenna on the higher frequencies, which is an effective performer for those who live in antenna restricted communities.

As with any transmitting antenna, be sure the radiating elements, especially the stinger end sections, are kept safely away from bystanders. 73

Member Comments:
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Hamstick Dipole Fact Sheet  
by AA1GJ on November 9, 2001 Mail this to a friend!
Steve,
Interesting review. I've been using a pair of 40M Ham Sticks in a dipole configuration from my boat with success.

Have you done any work using four whips configured as a Yagi?

I'm thinking of trying four on 14MHz or 18MHz using PVC pipe for the boom and storage carrier.

73's
Gary
 
Hamstick Dipole Fact Sheet  
by WB3FUM on November 9, 2001 Mail this to a friend!
Good article Steve. I need to add this to my bag of tricks.

73 Brian
 
Hamstick Dipole Fact Sheet  
by W0FM on November 9, 2001 Mail this to a friend!
Hi Guys! As a side note to your article, I have been using the Hustler mobile antennas, back-to-back in a dipole configuration for 7 or 8 years now. Hustler makes an adapter that allows up to four resonators to be attached to the end of each mast. I have found that I can use 40, 20 15 and 10 meter resonators simultanously with good results. Four band, instant band switching, without having to haul the dipole down. I have had success with this antenna mounted in my attic, rotated with a TV rotor as well as on the deck of my previous condo, mounted on a piece of PVC stuck in the umbrella hole on a patio table. Thanks for the nice article. Have fun. Terry, WFM
 
Hamstick Dipole Fact Sheet  
by WA2MZF on November 9, 2001 Mail this to a friend!
I have been using hamsticks with great success for a number of years.
Pro am is my ant of choice for a lot of reasons! most have all ready been
mentioned.
However what I would like to add is that I was lucky enough to be able to pick up
an electrical hot stick disconnect pole. These are very hard to come by but if you know
someone in theh power company give it a shot. It collapes to about 40 inches and is about
four inches in dia when down, goes up in about five seconds to about 30 feet plus.
I will have to measure it. But if you will look at pictures on my home page you will get the idea.
All parts are mirror mount cb ant stuff from radio shack and modified as pictures
will show, very easy to do, I do not have to worry about the pole being metal as it
is fiberglass thus well insulated. also you will note a coil of coax near the top
for a choke. When used on 40 or 20 people often think I have a beam ! which is
a nice report to get. What you cannot see is the bottom, I have that going into
pvc and with a u bolt on the front of the 5th wheel i am able to rotate
the thing in seconds. a super system..

Happy to ans any questions.

Look at my home page for other info

http://www.qsl.net/wa2mzf/

but the ant pixs you want are as below just change the number from
1 to 9 for diff pics..

http://www.qsl.net/wa2mzf/ant1.jpg

all lower case !! as said change the 1 to any number thru 9

73 WA2MZF


prentice@canton.edu
 
Hamstick Dipole Fact Sheet  
by VA2DV on November 9, 2001 Mail this to a friend!
I have tried a 80m version of the hamstick dipole
with 2 proam/valor whip and it works flawlessly.
Outperform Isotron and verticals ! Pick up less noise
than other antennas ! It's ideal for limited space
hams and can be disassembled in seconds using 2 quick
disconnect studs.I have add a 1:1 balun to keep the RF
from coming back on the coax shield.
 
Hamstick Dipole Fact Sheet  
by W0TLO on November 10, 2001 Mail this to a friend!
In response to Gary (AA1GJ), check
www.eng.mu.edu/~usi/hamstick.html
for an article about a 6 hamstick
3 element yagi for 20 meters. I have not tried
it, but it reads interesting.
Enjoy de W0TLO
John
 
RE: Hamstick Dipole Fact Sheet  
by W3JXP on November 13, 2001 Mail this to a friend!
Hi all:
I also made dipoles out of Hamsticks. I used 80m and 40m Hamsticks mounted as an "X" and feed in paralle. The gain and band width I saw were just the same as in the Fact sheet. Bottom line it worked but a I replaced it with a traped dipole of my own design, the differance was truely great. I can now work DX sometimes on 80m.
 
RE: Hamstick Dipole Fact Sheet  
by NB3O on November 13, 2001 Mail this to a friend!
The problem with using loaded Hamstick dipoles with parasitic elements for a yagi design is it lowers the feedpoint impedance significantly. This occurs when the parasitic elements are brought into proximity (less than 1/4 wavelength) to the driven element. Their already limited bandwidth will also become even narrower when using parasitic elements as well.
In some trap style as well as full length yagis, they compensate for lower feedpoint impedances by using a gamma match, hairpin style matching, balun, etc. The yagi bandwidths are usually narrower than their dipole counterparts unless additional "stagger-tuned" parasitic elements are added (like the Force12 C3 on 10 meters).
In many cases, the feedpoint impedance of a full length yagi can be below 30 ohms. In shorter trap loaded systems, the feedpoint impedances are even lower, unless the traps themselves add some resistive loss (at the expense of efficiency).
The lower frequency mobile loaded whips (40 and 80 meters) by themselves have lower radiation resistance than their larger, fixed station counterparts and thus lower feedpoint impedances. Again, the loading coil resistance often helps increase this number, but would not be enough to raise it into an easily matched range when implemented as a yagi with parasitic elements. An alternative would be to use an external matching transformer, but again the bandwidth would become more limited.
For receiving, this situation is non-critical and some folks have actually put together directional trap loaded systems. QST featured a four-square active antenna array for the lowbands that was fairly short in height.
For transmitting, the major challenge would be trading off efficiency and bandwidth versus complexity. Given this, I would explore a short, high-Q tunable loop design first for a compact directional antenna (see June 1986 QST) and add parasitic elements onto it. 73 de NB3O
 
Hamstick Dipole Fact Sheet  
by KC7PGU on November 30, 2001 Mail this to a friend!
I used this configuration to build my first antenna--two Hamsticks in the adapter, bolted to a 10' high piece of PVC, raised another 3 1/2 feet by putting it on top of a garbage can, and tying the pvc mast to a hook on the back of my patio roof. It takes about 5 minutes to put it up and get on the air.
I only have a 25 watt, 10 meter monobander. This setup surprised me with how well it worked. I used a cheap SWR meter to trim the whips, and when I was done the SWR was 1.1 across a good part of the band, and was only 1.5 at most.
Yesterday was the first full day I used it, and I worked several states, including Rhode Island--2200 miles from here in Arizona--and got good signal reports back. One guy I talked to came in so strong I thought he was somewhere close--turned out he was mobile in Portland, OR.
Heard lots of great DXing going on, too. M5LRO, in Rochester, UK was nice and clear across the pond. I didn't reach him, but gave it a try a few times.
I'm going to try getting the antenna up a few feet higher, maybe try it indoors, too, on the second floor of the house, or in the attic.
This antenna fits my needs of something I can put up or take down in a few minutes. Not having to use an antenna tuner is a bonus.
 
Hamstick Dipole Fact Sheet  
by K8JWT on July 30, 2005 Mail this to a friend!
Very interesting as I am looking into a similar setup for myself but was wondering if I put up a 80meter dipole with these sticks could I use a tuner to work other HF bands? Like you would a regular dipole?

Jacob Tennant - K8JWT/AG
 
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