Latest Antenna build. 6 element

[Century21]

Let me see if i can get these pics in here. This is an antenna I built for Groundhog 51 in NC. I had pics of the assembly on the ground. But cant find them now. So here are the installed. I didnt put it up, as I dont climb towers no more. The man that put it up, hooked a darn groundwire to the boom. Which will be off if I have to climb it. And also left it **Censored** a little.

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[linx]

Nice! Thanks for sharing!

[403]

Nice job looks good.That beats a T-post beam lol What did you use?

[Century21]

Nothing wrong with your t post beam! Thats being creative. And thats cool.
I actually used a brand new m106 ( which i modified ), a Walkie Talkie Gamma match, LMR-400, and a yaesu sdx800 rotor. The man had a 4 element someone designed for him that would not work. And I told i could hook him up, but it would all be my way or no way. This way if it dont work, im the one to blame. He said ok, came to the house with credit card, purchased everything. Assembled it, let it sit on the ground for a month. And now its up lol. The antenna expert that installed it for him hooked that wire to the boom. But I may have to break out the safety belt after all and get rid of that wire.

[PONY EXPRESS]

Actually that Truss support AKA your ground wire will be a very nice modification to keep that antenna up in the air.
What I did not understand was the support on the reflector element .

Overall nice looking antenna that appears to have good spacing on the 1st director from the driven element.

nice Job

[Century21]

must have miss understood something..... I made the truss...... he attatched a wire to the boom near the mast plate. Then ran it down to the ground. Not my way, I would never do that. The truss is on the reflector because it is the only element that sags. I like all the elements PERFECT. I know they may sag some with ice or something on them, but thats to be expected. It was measured 5 times, from 1 element end to another, from the middle of an element the next, and the elements were measured 5 times to make sure length was on my figure and centered up exactly on the boom. Does being that picky matter...... In my world it does.

['Doc]

I may be missing something somewhere. Take this as an honest question, I'm not taking exception to your work. So why would using a ground wire from the boom be objectionable?
- 'Doc

[Century21]

Hey doc, its just personal, why would you need one? its all metal, connected to a metal tower 3 feet in the ground. Why risk ground loops and how long is it going to take before that aluminum ground wire breaks from turning anyways. I always use 3 ground rods at the bottom, a " devils triangle " and attach it to the bottom leg of tower. But they probably dont need that simply because the tower isnt even in concrete. its firmly attached to the building and sitting 3 foot in the ground. Guy wires and all that distort patterns to some extent, and having a ground wire that long could cause problems.

['Doc]

Okay, I sort of figured that, but didn't know if there was a particular reason or not.
I figure that tower is going to provide a larger 'conductor' than any wire I'm ever liable to use for a ground, makes sense to me.
As far as grounding a tower, I think I'd go to a lot more trouble than what you gave as an example. That's basically a 'safety' ground, very seldom an RF ground since they are just not needed in most cases. A 'safety ground' (lightning, etc.) has to be able to dissipate a huge amount of current so making that 'safety' ground huge is a very good idea. I'm sorry, ground rods just are not very effective for anything really, so I would tend to over-do those ground radials. Their effectiveness is directly related to how many are in the dirt. One of the few times when more/bigger IS better. Can that get ridiculous? Of course it can. Unfortunately, I get fed up with putting in radials before it ever gets that far.
- 'Doc

[Century21]

Yeh, i think we had that discussion the other nite in another topic, about grounding being really for safety reasons rather then RF. And I was thinking while reading your post, I cut the ground wires going to my tower bottom a while back, over a year ago, and never hooked it back up... I must be really worried about it. I never have been one to get into grounding antenna's to much. Especially a beam. Now at the shack is a different story, but its all electrical grounding, but i still use the same rule.. SHORT as possible. I have a 5 foot ground wire going through my shack wall, strait down to 3 8 foot ground rods. And only 2 foot going from the chassis of the big box to that wire which is attached to the bus. And where them ground wires are, is where the run off from my roof is, so the ground stay moist. I also have a 10 aluminum rod at my panel box in the shack, which is also the same i have for the house. Duke Energy man Cosmic Blue, help me understand that. #1 cause of fires in a house is BAD GROUND. I used to try and re-direct rf with grounds and stuff to keep it out of the shack. But after my last Antenna, I tuned the antenna to 50 ohm...... And just hooked it all up. SWR and Reflect is very satisfactory, But im not talking off my coax niether, I dont have no coax balun, no sleeve, nothing, and my computer speakers sit on top of my radio. I do not bother them.
I went to an am radio station one time, and they were telling me about all the grounds and counterpoises they had buried in the ground beneath the tower, it was unbelievable. Oh yeh, the tower was the antenna.
And I have a gap titan multiband antenna that has like a floating counterpoise, but the other models you actually put the counterpoise on or under ground.

And one more you may agree with me on, the safety grounding, Thats a good idea. These amplifiers now day everyone is running with steel tubes and all in them, 2400-7500 volts, Hate to see something happen and a good ole arc over to your lips when talking on that big silver rf collector d-104 lmao. After all, whether you only have 1 ground or what, everything in the shack is connected on the chassis through the shield of the coax. Why i only ground the big one... REALLY GOOD. We could discuss stories and stuff allday long and everyone will have there own opinion and own way to do things. Not saying my way, or anyone elses is less or better. But thats the way i do things and it has always worked well for me. And thats what matter.

[Double D]

So what are the vital statistics of this design in terms of gain, F/B, etc.

[Century21]

That depends on the hieght off the ground. I designed it for 45 feet, and well its barely 40 i think. Dont sound like much. But it changes things, even gain, and pattern. But it is workin good none the less and he is tickled because it works a lot better then his moonraker.
I dont know the figures off the top of my head. I will have to wait til i get home.
The gain was probably around 12.4 F/B around 24 or 25.... dont know for sure yet til i check when i get home. And get on the air with him. He does have a imax to compare it to, but i dont. Side rejection is awesome, rear is typical 9 s-unit drop maybe, and of course the back corner you can null people out of the picture. The front is about 10 degrees to 15 the most before you see a significant drop in signal. I dont like a tight beam. Point it towards texas and i can still work alabama, louisiana. But not florida. And 12.4 dont sound like much, but im telling you things other manufacturers wont!, height off the ground is key. And if a moonraker is suppose to have 14 db gain, and this one 12.? And it out talks the moonraker. It makes you wonder about that stuff. ofcourse 2.5 db is almost a half a s-unit, not much anyways. But the hieght and angle of patteren on the elevation plane is most important factors when deciding what you want and what your looking for. 1 thing i would always preach and still do... and 403 is probably finding this out.... ANY BEAM is better then NO BEAM, when you want stronger DX, and more from the direction you want to hear and be heard in.

[Double D]

Hmmm, 12.4DB? Is that DBi or DBd?

[Century21]

Its probably dbi rating, not dbd, ill have to wait til i get home. DBD is probably around 9 to 9.5 i guess. But what im getting at, you can have an antenna with 100dbd dbi or what ever.....If your main lobe off the antenna is straight up, or 55 degrees on the elevation, then its worthless... There more to an antenna then #'s, and that where a lot of people get caught up is in the fancy numbers some manufactures give. How bout the ones that give you an audio gain.. lol... Well heck, my antenna might be 9.5 dbd, but it gives a "A"Gain of 145%, thats attitude gain. I just came up with that new way of measuring antenna gain.

[Double D]

Antenna makers need to be more specific when it comes to the numbers. They need to specify height off ground, takeoff angle, DBi, DBd, 3DB beamwidth, gain, F/B, F/R, and 2:1 bandwidth. I guess it's asking too much for just the basic info.

[Century21]

I checked it out... His im not sure, its only 40 ft. probably around 8.77 DBD, I have the same thing at 55 ft and should be around 11.06 dbd on channel 6.... channel 21 the gain comes up a touch, but the F/B ratio comes down. On channel six the F/B ratio is actually 37.73 on 21 its only 21.25, according to the program i modeled it on. I think i actually designed it for max F/B with a decent gain for channel 6. But it was 2 years ago. I dont remember no more. put his hieght in and it shows a F/b of 35 on 6 and the gain i stated above. The main take off angle on mine at 55 ft is right around 10 degrees and another strong lobe around 28-30 degrees and on real weak one at about 60 degrees. Hope this all sounds reasonable. This program hasnt failed me yet.

[Double D]

I modeled the MACO 6 and i get 8.81 DBd and 10.96 DBi in free space. 36 FT over average ground i get 15.92 DBi @ 13 degrees elevation. Your numbers seem some what conservative.

[drdx]

I'd think your gain numbers are close, if not conservative, and rather think conservative and be pleasantly surprised for sure. It looks great. On the reflector wires, are they taken into account in the antenna model? I'd think that because they are in the same plane that they would add to the loading (or electrical length) that the reflector provides and affect the performance and possible radiation angle. Probably not much, but I'd think it would make it appear longer.

I think a moonraker 4 is probably an honest 8 dbd fwd gain at BEST and maybe lower if we ever really knew the truth.

-drdx

[Century21]

Your probably right on the moonraker, They reflect wires is Dacron rope. 3/16 i think. So its non conductive. I use Dacron or philly stran on every thing. Im sure my numbers are conservative. But as i said before it was all modeled for channel 6 and i look at the lobes and other things rather then gain. 1 or 2 db will never be noticed. But if your putting that RF in the right directions, then your doing something. A friend of mine has a amp with 7 500'z's dont know why, but he has it, it has enough transformer for 10 and the sockets in it. All he gotta do is plug them in. Dont know why someone would want that many $$$ tubes. But his 6 element is tight as crap, just the opposite of mine. and about 75% time when we key down together in my target, im heard. But a lot plays in with that also.
If you get bored later, send me them specs on maco 6, id like to put them in my program. I gave the manual to the guy that purchased the antenna.

[Double D]

I just sent you a pm.

[Century21]

Well.. i put the figures in for channel 6, think it was 4 -7 from maco....
And my program is def stingy...
gain was 11.91 at 55 ft and the F/B ratio was 10.28.. I didnt check the pattern or nothing out.

[Double D]

You need to upgrade your software.

[Century21]

Not going to happen anytime soon. I have used this software for over 10 years, and built many antenna's. Never has let me down, even put my antenna stuff into another software program... And according to it, it sucks. But I spend many of nites testing it, It dont suck. I talk on the bowl, 11 and any other channel with a lot less power then most, and even when the big hitters are out there.
Thats what happen when ya pay attention to numbers, you get cought up in the hype. Its not about numbers, its about putting that RF where it needs to be. And that is what I do.
Yesterday when i got home from work, i unloaded a bunch of cb stuff from the car, hooked up a realistic from 1978 and a 2 tube elkin, maybe 45 watts on the bird. And was talk DX all over. And it was noisy out there.

[Double D]

Numbers are important, when they're accurate and properly interpreted. I'm curious, how are those gain numbers being calculated in your software? Is it all free space numbers or is it using a ground model? An accurate ground model is imperative to good modeling.

[Century21]

Ill have to check on that man, im not sure. The help files and info on the program isnt great because they want you to register it.