Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: 40 meter wire vertical  (Read 6718 times)
KJ4I
Member

Posts: 113




Ignore
« on: August 23, 2012, 10:10:33 PM »

Just got a little curious and thought about throwing together a 40 meter wire vertical antenna this weekend to see how well it would work for 40 meter dx. I have taken somewhat of an interest in that lately, especially later in the evenings. Thought about home brewing a design similar to one that is marketed in the link below. Would be really simple and easy to build out of existing parts laying around in the junk box. Especially being on a tight budget at the moment. I would be interested in hearing ideas or experiences from others on such a design or any other simple easy to build antennas that might be feasible for a 40 meter dx antenna. It don't have to be the most optimal antenna but rather something that is simple and easy to get started with. I'm not necessarily looking for a stellar design to bust pileups or add a whole new dimension to 40 meter dx just something to tinker with and get my feet wet.

Jason, KJ4I

http://www.amateurradiosupplies.com/v/vspfiles/assets/images/40m_vertical_monopole_-_manual.pdf


Logged
WX7G
Member

Posts: 6312




Ignore
« Reply #1 on: August 23, 2012, 10:27:54 PM »

Jason, that is a fine antenna design.
Logged
N4JTE
Member

Posts: 1159




Ignore
« Reply #2 on: August 23, 2012, 10:32:19 PM »

Well a dipole would serve you better if you have the room, that being said phase a couple and you will see a big differance, have a few articles here on eham under my callsign.
Bob
Logged
W5DXP
Member

Posts: 3639


WWW

Ignore
« Reply #3 on: August 24, 2012, 04:39:46 AM »

Jason, that is a fine antenna design.

Maybe for a vertical.Smiley EZNEC sez the maximum gain is 0.13dBi at a TOA of 25 degrees. It is true that a dipole at 40 feet height has a TOA of 50 degrees (but with a maximum gain of 5.5dBi). And here's the rest of the story.

The 40' high dipole has a gain of 3.4dBi at an elevation angle of 25 degrees, i.e. at the vertical's take-off-angle, the dipole is radiating double the power of the vertical in the two directions favored by the dipole. For 180 degrees of the compass, the dipole has more gain than the maximum gain of the vertical at the vertical's TOA of 25 degrees. Of course, for the other 180 degrees, the vertical beats the dipole at an elevation angle of 25 degrees sometimes by as much as 7 dB.

If the DX one wants to work is broadside to a dipole, it is hard for a monopole (with the same maximum height as the dipole) to compete.
Logged
KC4MOP
Member

Posts: 764




Ignore
« Reply #4 on: August 24, 2012, 05:08:55 AM »

What is the maximum height of the vertical you are thinking about? 1/4 Wave? 32' 6"  1/2 wave 65'
This is the magic 5/8 wave 81'. Gain and 16 degree TOA.
Strictly a DX antenna.
The higher radiation will also work but not for the long DX. 40m is a lot of fun. You picked a good band.
40M is easier to make phased arrays using verticals or dipoles for even more gain.

fred
Logged
WB6BYU
Member

Posts: 13565




Ignore
« Reply #5 on: August 24, 2012, 08:53:27 AM »

If anything, that article is too prescriptive and limiting on how to build the antenna.
You actually have a lot more options.  Personally I'd try to get the top of the vertical
wire up higher (or bend it over if necessary) to get the feedpoint higher off the ground,
and angle the radials downwards.

But, basically, it isn't difficult to build a wire vertical:  a quarter wave vertical wire
hanging from a tree branch connected to the center conductor of the coax and two or
more wire radials.  An effective feedline choke helps to reduce the RF flowing on the
outside of the coax.

My suggestion would be to make a temporary version using light hookup wire or whatever
you have on hand and see how it works.  If you like the performance, then consider making
a more permanent version.  Also consider putting up a dipole so you can compare them.
Logged
N4JTE
Member

Posts: 1159




Ignore
« Reply #6 on: August 24, 2012, 12:40:49 PM »

My concern for a new antenna experimenter is that a vertical is not the easiest antenna to build correctly. All the superlatives about take off angle etc, only apply to a well constructed ground system handling the near and far angle of incidence to do the reinforcing magic. If there is one antenna bound to the, location, location constraint, it is a single monople.
Horizontal wire or wires are much less influenced by ground losses near and far.
Good luck and keep building !
Bob
Logged
WA2TPU
Member

Posts: 224




Ignore
« Reply #7 on: August 24, 2012, 01:50:56 PM »

Have you looked at a 40 meter vertically polarized Delta loop antenna? I've had real good luck with them over the years and when using thin wire they become nearly invisible to the neighbors.. I've also had fun with Half Square antennas too. Just go ahead and experiment with wire types they are indeed the least expensive to build. 40 meters is by far my favorite band for both state-side and DX contacts.
Regards,
   Don - WA2TPU. REAL QRP HERE!
Logged
W5WSS
Member

Posts: 1780




Ignore
« Reply #8 on: August 24, 2012, 07:25:37 PM »

I agree that "if one can erect a horizontal dipole high enough that it will perform as W5dxp and others have stated, but for the many that do not have the option of installing antennas that high the mono band,or multi band vertical family of antennas is a viable option.
Logged
WA4FNG
Member

Posts: 162




Ignore
« Reply #9 on: August 24, 2012, 09:32:12 PM »

Jason,

You will learn a lot by building antennas. However, it's very helpful to have at least one other antenna for the same band for comparison. The basic dipole, at a decent height, is a very good reference antenna. As was mentioned earlier, it's hard to beat a dipole at decent height for DX. However, a vertical could reach a distant station that is off the end of your dipole. Build it, try it out -- great experience.

73, Milt
Logged
KJ4I
Member

Posts: 113




Ignore
« Reply #10 on: August 24, 2012, 10:46:08 PM »

Thanks for all the excellent information. Hopefully I can touch a little on everyone's points and questions here. For time being I'm gonna suspend it from as near the top of the tower and as far out as I can. The tower is somewhere around 45ft. It will probably get moved out to a tree branch a little later on just to get it a little more in the open away from everything else. Unfortunately I don't have near the vertical real estate that I had a number of years back but I have plenty of land area so that is not really an issue. I currently have a 1/2 wave 40 meter dipole suspended about 40ft at center running mostly north to south. It should make decent comparison antenna. The vertical wire will be a 1/4 wave design. I have been in the hobby now for about 16 years and I'm getting to the point of trying different things that I just never found the time to tinker with in years past. Antenna building and experimentation has always been one of those areas of amateur radio that has always peaked my interest. Other than modifying a few yagi's and verticals or building some stuff for the higher bands I have not done much antenna experimentation other than standard dipoles or inverted vee's, especially on the lower bands but now I think is a good time. I had considered a delta loop setup like someone mentioned and that might actually happen in the near future. I had experimented with a makeshift 10 meter delta loop some time back and I was actually pretty surprised at the positive results that I had with it. In fact, building a fully functional 10 meter delta loop is probably gonna be one of my next projects. 40 meters has always been one of my favorite bands for a number of years. I'm hearing quiet a bit of DX in the evenings, especially from South America and Europe but unfortunately I'm not really able to get the dipole up any higher to see what difference it would make hence the vertical idea. I really have not had any success trying to work any of the distant stations with my current antenna arrangement (dipole). If all goes well hopefully I can get the vertical up and going in the next day or two and see what it will do. I gotta say, building it your self and seeing it work is half the fun in amateur radio.


Jason, KJ4I

« Last Edit: August 24, 2012, 10:50:06 PM by KJ4I » Logged
G4AON
Member

Posts: 545




Ignore
« Reply #11 on: August 25, 2012, 02:42:45 AM »

For an easy and neat to build vertical I would get a 32 foot fibreglass fishing pole, flag pole, or similar. Here in the UK they are plentiful and cheap on eBay. Ground mount your fishing pole with a wire up the side and bury at least 16 radials, they will work best on 40m if 2/3rd the expected length due to the de-tuning effect of the ground (22 foot long as opposed to 33 ft). You can get away with as few as 2 tuned radials when they are elevated but for ground mounting at least 16 are needed for half decent performance, they do not all need to be 22 ft...

Depending on your ground and wire insulation, you might find the vertical wire is less than 32 foot long, so it will "fit" OK on a 31 ~ 32 foot pole.

The ground mounted vertical is a lot neater than an elevated one, unless you happen to have a suitable roof to mount one on.

There are some ideas for multi-banding one on my web page at www.astromag.co.uk/vertical/

73 Dave
Logged
WA4FNG
Member

Posts: 162




Ignore
« Reply #12 on: August 25, 2012, 03:21:11 AM »

Jason,

The tower is likely to influence the pattern of the vertical. Not my personal experience (no tower) but have read this comment from others. With a tower you could try slopers into several directions.

-Milt
Logged
W8JI
Member

Posts: 9296


WWW

Ignore
« Reply #13 on: August 25, 2012, 03:44:26 AM »

Missing in all the advice is the most critical thing. The most critical thing is missing from the web link at W8AMZ also.

Any vertical or end-fed using a small sparse ground system, like the vertical being discussed, will have considerable common point to earth voltage.  This will drive the feedline with considerable common mode, and any path to earth will increase loss. Sometimes not isolating the counterpoise from earth can add 5-6 dB loss. The feedline needs a 1:1 current balun at the feedpoint, or a  common mode choke of some type at the feedpoint.

I'm surprised more people do not understand that, because it has been mentioned for at least 20 years that I know of. If you have enough radials, like 15-20 radials, it isn't an issue. With only two radials it is a severe issue.

73 Tom


Logged
W5DXP
Member

Posts: 3639


WWW

Ignore
« Reply #14 on: August 25, 2012, 07:52:28 AM »

Any vertical or end-fed using a small sparse ground system, like the vertical being discussed, will have considerable common point to earth voltage.

I'm not sure I understand the EZNEC results. I modeled the antenna over mininec ground. The result was -0.04dBi at 23 deg TOA. The current in each of the radials was 0.5 amps, half of the supplied current. I then added a wire from the junction of the two radials to mininec ground to simulate a common-mode path. The result was 0.0 dBi at 22 deg TOA. There was 0.15 amp in the simulated path to ground and 0.57 amp in each of the radials. The simulated common-mode path to ground increased the current in each of the radials by 14%.
« Last Edit: August 25, 2012, 08:00:29 AM by W5DXP » Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!