I have recently been volunteering for antenna work in our local area trying to learn more about our hobby.
I helped put up an antenna that I had never seen before. #We put up an antenna that was made of 2 mobile #antennas, 2-20 meter hamsticks, used as a dipole for 20 meters.
I am new at ham radio and joined the local club. A fellow ham showed me how you can take 2- 20 meter hamsticks and convert them to a horizontal 20 meter dipole.
I was quite impressed! We are going to put up a 40 meter dipole too. #I got the job of climbing the tower, of course, I am the "young-new guy".
It was 36 degrees outside that day with a wind of about 20 miles per hour. (that is another story) #I actually learned quite a bit! #You can make low frequency dipoles from mobile antennas!
This has become the "ultimate" antenna in our area now. This antenna has all the same results of the "big" antennas but takes up a lot less space.
Can we get them in 160 meters? #I hope we can wait for warmer weather to find out!!
|Yes Jeff, 160 meters is possible. #When I was a newbie a bunch of old timers show me a can of eXtended Range Antenna Wax that they just raved about. #I got so excited I put it on my home TV antenna. #When I reported to them that "nothing happened" they told me that "it's only forumlated for ham frequencies". #Ah Ha!, I thought, this is going to be a lifelong learning experience.|
Welcome to the hobby!
I have to agree - those ham stick dipoles are the tops! I was running a vhf station at my club's hamfest w/ my 706 MKIIG. I took (and passed) the general and code tests, went to a vendor, bought the kit (about $50) and 15 minutes later was making psk contacts in Europe! I'll be getting a tower one of these days but for now I'm convinced.
Sounds interesting. Is there a site that gives plans and layout for building these sort of antennas? Are they for towwers only or can they be hidden in an apartment?
|Quote (ke5wj @ April 10 2002,18:22)|
|As far as efficiency, shortened antennas are never as efficient as a full-sized one. The radiation resistance drops as you shorten the antenna and it also loses resonance. The resonance can be handled by loading it with a coil, tuner, or other impedance matching system, but there's not much to be done about the radiation resistance - which represents what actually gets radiated. When an antenna gets very short, the resistance in the wires, coils, etc. gets higher in relation to the radiation resistance, so the antenna efficiency drops.|
However, again, it's all relative. If you don't have room for a full sized antenna, at least the shortened version will get you on the air.[/QUOTE]
I agree with the quoted portions of this post. #I also disagree with other points made in the rest of it. #Bottom line is this---if you have the room, make it count and use a well-designed, full size antenna. Otherwise, use what you can get away with.
As far as the side note about six meters, I congratulate its author on his VUCC. #However, six meters is much more affected by one's location than many HF bands. I too, earned VUCC on 50 MHz, but I guarantee I could NOT have done so with the author's arrangement in the attic---so a Yagi was installed last year, which helped solve my problem of bad geographic location. #Without that Yagi, I could not have earned VUCC.
ARRL Volunteer Instructor
#IS-002 # # IS-100
#IS-271 # # IS-275
#IS-288 # # IS-292
NWS/Skywarn Certified Spotter
ARRL VUCC 50MHz
Bottom line: A compromise in size is a compromise in performance. A rubber duck will work just fine on your 2 meter walkie talkie, but move away from the repeater and it won't work as well as a 19" whip. Fact, not fiction. If the repeater is a mile away, you'll never notice. But that doesn't mean the duck is working as well as a whip would work.
No sir, that hamstick dipole is NOT as good as a full size dipole. But if that's the only game in town, it beats not playing.
I have heard of hamstick Yagis. That would give you some gain, so you may be able to out-perform a dipole (of course,you would need a rotator, though). I don't know how they work, but I guess you proably change the size of the whip or otherwise make the reflectors longer and directors smaller. Hamsticks are 7 feet long, so the elements would be about 14 feet across. It may be better just to get a tribander.
I use a variant of the HamStick dipole for 10M. My 10M rigid-rotatable dipole is made from 2 normal fiberglass CB whips, pruned to 10M, and works well with no more than 1.5 SWR across the 10M band. It is up at about 32 feet. Also, with the tuner, it will work 10, 12, 15, 17, & 20M. I also have experiment (at a JOTA event) with one made out of 1/4" diameter 304 stainless, with equal results.
I just recently tried this for 40 m, and it worked ok. I had the two elements up about 15 feet (one possible reason for poor matching) and the two elements are not identical. One is a Ham-Stick from about 10 years ago, and the other is an MFJ variant about a year old. The are of slightly different physical dimensions (coil size, whip length are a few inches different.) As far as the Yagi goes, shorter antennas have lower radiaton resistance, and using parasitic elements may likely compound this problem. My antenna support was a PVC mast that requires no guying and holds two pair of these dipoles, although to date I have only put one up in the air at a time. Since I live in a basement appartment, I wanted something that could be put up/taken down by one person in 5 minutes, in the dark, and this works fairly well.
Conserve bandwidth-QRS PSE!
Murphy's law has taken effect. Up until I read the original message yesterday, at least once a day I would come across the website that sold the required adapter to construct this Ham Stick Dipole.
Of course, now that this info would be good to have, I can't find it.
But I'm still looking.
It's really quite easy to construct, two fiberglass whip bumpermount adapters put back to back...offset so PL-259s can be attached. But I wish I could find the website...
73, Jim - kc2jca
For those interested, here is an article on the subject of the Hamstick Dipole. #Included in the article are several references, including one to what I believe must be the web site that Jim was looking for.