quad reflector versus yagi reflector

[Toll_Free]

Toll Free,
Will I give my call sign and ask questions about that? Sure! And that ought to at least give you pause to wonder why I asked it, shouldn't it. Speaking of directional antennas, a 1/2 wave driven element is no less efficicent/affective than a full wave length driven element. There are electrical chartacteristics that are different between the two, but efficiency isn't one of them.

Which I understand, and tried to explain later (2nd post).... IE, referring to patterns of radiation.

When you get right down to it, the radiation patterns aren't all that different either.

NEC a plot for a quagi driven and reflector with yagi directors. Seriously, if you can. I'd love to see the differences between quagi reflector / driven and standard yagi. As I said, I've done quite a bit of reading the last couple weeks, and everything kind of points to the quagi thing.

A 1/2 wave element is no more 'resonant' than a full wave, and visa-versa. It's either resonant or it isn't.

That's a no brainer. Resonance isn't being questioned, I believe, it's what's better. Better, in CB and antenna terminology, usually means more efficient. Efficiency and bandwith are the name of the game, no? I mean, for all intents and purposes, we all want a log periodic bandwith with long boom yagi characteristics for forward gain, but we want close-spaced "back-doors".

I really do know what reciprocity is. As for the 'inverse reciprocity" thingy, no, I have no idea what you meant by that. It really doesn't make sense as stated. I guess I shouldn't have made fun of it, but I couldn't help myself, it is funny. I appologize for that though. The inverse, the opposite, of reciprocity is no reciprocity, which says to me that receiving just isn't going to be the same as transmitting. (Come on now, tell me the truth, thats not exactly what you meant, right?

That's what I meant, and that's also what I pasted later to affirm my statements. I had also disclaimed that I wasn't positive that the 'name' I branded to the rule was correct.

Funny or not (and yes, it is, was, and will be when it's told around all the ham-fest, keydown and club meetings for the next umpteenth months) I believe you knew what I was saying

And that is funny, isn't it.)
Everybody makes mistakes, I know that. I think some of the 'boners' I've come up with are funny too, so no big deal as far as that goes.
As far as the long antennas verses short antennas thingy, the primary difference is their respective radiation patterns. The next 'biggy' is in the practicality of the length/size of the thing. Shorter antennas are just a whole lot easier to put up, and/or live with. That doesn't say that they are 'better', though, which really just depends on what you want to use them for anyway.

Which, again, was pretty much what I was trying to say.

If you research "me", you'll find I can be really argumentative. Trying not to do that here, so if I come off as a bit defensive, I don't mean to be. .....

But seriously, how much 'harder' is it to set up a quagi vs. a yagi reflector antenna..... For the gains that you get with the quad driven, why not? Wider b/w is just one.

Now, if I could only get a quad wire that would hold the 4cx5k... Time to break out the calculator and figure out the wire guage I'd need for that.

Have a good night, no offense taken. ttyl.

--Toll_Free

Enough of all that. I appologize again for making fun, and I definitely won't attribute it to you, but I do certainly plan on remembering the phrase! It's a good one.
- 'Doc

 

[Master Chief]

If you research "me", you'll find I can be really argumentative.

I thought you were really an, "asshole" rather than "argumentative".....at least that's what everyone said on rrcb! I'm glad to be set straight on that!

So how are you liking the WWRF so far, Toll?

 

[Mr Clean]

A perfect quad would be round from what I have been reading. Just hard to build. Ive been kicking around the idea of building a quad out of small tubing. Only problem I can see would be weight. And back to the question at hand. In theroy a quad reflector would be better.

 

[Master Chief]

I've never tested this.

I personally know Wayne Overbeck who invented the Quagi. The quagi has both a driven and reflector quad element so it doesn't apply to your original question. For information sake, you can read more about the Quagi here:
http://members.optusnet.com.au/jamieb/quagi.html
http://www.cebik.com/vhf/qy.html

It is my OPINION, that you are better off using a Yagi element with a Yagi driven element and a Quad with a quad driven element.

Of course my favorite antenna manufacturer (besides Jay and Steve) throw all of this to the wind with their Moonraker antennas. When the world zigged, Avanti ZAGGED!

 

[Beetle]

Might be an interesting exercise (and may already have been done): take a yagi director and reflector, with a quad driven element...and with the polarity of the DE changeable from horizontal to vertical. See what combinations work and which don't...

 

[Toll_Free]

A perfect quad would be round from what I have been reading. Just hard to build. Ive been kicking around the idea of building a quad out of small tubing. Only problem I can see would be weight. And back to the question at hand. In theroy a quad reflector would be better.

A perfect quad would be any antenna with 4 sides.

A perfect circular antenna would be round.

A perfect dipole has two sides.

Understand? The 'term' quad means 4 sides, not round.

That's what got me into trouble in this post in the first place


--Toll_Free

 

[Toll_Free]

If you research "me", you'll find I can be really argumentative.

I thought you were really an, "asshole" rather than "argumentative".....at least that's what everyone said on rrcb! I'm glad to be set straight on that!

So how are you liking the WWRF so far, Toll?

Snot bad, snot bad at tall.....

I am Toll Free, TollHolio, The Toll Hole, Eye Uh Toll Uh, Ayatollah Assah-holah (no, I didn't make that one up, I stole it from Khomeni), and a bunch of other things not fit to print.


Reverend Doctor Asshole comes to mind, Richard Cranium, Doctor Proctor (with Dr. Proctor's rectum rocket, guaranteed to put more pep in your step and glide in your slide)............ Should I continue. Radio shows have brought out multiple personalities

--Toll_Free

 

[freecell]

"I am rebuilding a moonraker four and I am thinking about replacing the quad reflector with the yagi style.Is there any real benefit between the two?"

the quad loop is twice the length of a dipole. even after taking into account the decreased diameter-to-length ratio for the quad wire element the full wave loop still creates an aperture that is somewhere between 1.5 to 2 times the aperture produced by the dipole. aperture equates to total capture area. whether you plan on testing each for yourself or not, the quad loop has a clear advantage. the larger the capture area the higher the signal levels are resulting from the induced voltages and that works both ways. this is why the 2el quad and the 3el yagi are comparable in performance while a 3el quad can produce up to an additional 2db.+ by comparison. most modelling programs show 1db.+ (EZNEC3, 1.11 dbi) favoring the fullwave loop over the dipole prior to being incorporated into any multi-element parasitic array. my own tests indicate that the EZNEC3 figure tends to lean to the conservative side when compared to actual results in the field but not by much.

the moonraker 4 and 6 were designed and built as quad-yagi hybrids and that's the way they should remain. if you want to have some real fun just convert the entire array to a 4el. quad.

more data available.

 

[C2]

just don't forget, copper conducts electricity better than aluminum. :roll:

 

[freecell]

silver is better than _c_o_p_p_e_r_

 

[C2]

LOL

The colder it gets, the better it conducts

 

[Mr Clean]

OK a full wave antenna. My bad Toll. Peace

 

[Jay in the Mojave]

Hello Smokecraft:

A few suggestions that might make the Moonraker 4 rebuild and modification go a little bit smother for you.

1- Rebuild the Moonraker 4 stock, make sure the element spacing and element lengths are dead nuts on according to the assembly instructions. And Gamma Matches are also set per the assembly instructions.

A crank up and tilt over tower are almost a must when trying out and testing all the different configurations. Or some other way to have quick access to the antenna, done safely.

With a stock rebiult Moonraker 4 and say a omni antenna at least 50 feet away with the antennas coaxes connected to a good coax switch, (like a Diwa) you can swing the beam around and make many S-meter comparisons. Write them all down, day and night.

Then swing the beam around trying to attenuate the received station as much as possible. And write all this down for local and distant stations. By measuring the rejection of the beam will tell how much the beam will reject received stations. And this is a great indicator that the beam is working correctly. For the Moonraker 4 beam, you will see a deep and sharp null of rejection at 100 to 110 degree's from the forward heading. It should be close to -40dB of attunation.

It is possible that the Moonraker designers, designed the element spacings just for the Quad Reflector. I have heard of several Moonraker 4 modifications but never anyone say they work better.

2- Now install the Yagi type reflector, and rerun all the measurements. What I think you will see is not such a deep null at 100 to 110 degree's off the forward direction, and less rejection off the back of the antenna.

But I don't know as I have never run this comparison test.

3- Be real careful with the Moonraker Hubs, that attach the elements to the Boom. As their are around 40 years old, they are fragile and will eaisly crack and break. If you don't have to unbolt them, I wouldn't.

These hubs are Cast Aluminum, and where not designed to open and close a lot. I remember installing new Moonraker Beam Antennas, and having a Hub break right out of the Box!

4- Replace the cheap hose clamps with good marine/aircraft grade stainless steel hose clamps. And use 2 each on both sides of the Boom. This will be a big improvement, to hold the end elements from twisting in heavy winds.

I am now rebuilding a Moonraker 6. Replacing the smaller Boom with a 2 inch diameter Aluminum Boom. Replacing the Element to Boom Hubs with Billet Machined Aluminum Hubs, and a new simplier Trust system. But it sure is time consuming!

But I will start out with the stock verison, and then modifiy the Moonraker 6 with a better design matching system, and maybe a better spacing design. But I will make a lot of comparison tests.

Good Luck, hope to hear how it turns out.

Jay in the Mojave

I am rebuilding a moonraker four and I am thinking about replacing the quad reflector with the yagi style.Is there any real benefit between the two?I can build both, just wondering what you guys think. Thanks!

 

[Toll_Free]

Hello Smokecraft:
But I will start out with the stock verison, and then modifiy the Moonraker 6 with a better design matching system, and maybe a better spacing design. But I will make a lot of comparison tests.

Good Luck, hope to hear how it turns out.

Jay in the Mojave

Oh how I can't wait to see the results of both these tests.

How about a quagi reflector / driven vs. moonraker style reflector / driven comparison? I'm very interested in this, since I've done a gongola of reading on it, and everyone so far says quagi config..... I'd be interested to see if you've played at all with this? YOUR the antenna expert (wasn't it easier being a newbie on rrcb and NOT having your inbox innundated with emails from EVERYONE )

I might have to put something together around here for 2 meters and see if I can figure out what works better. Lots easier to build for 2 than 11 meters!!!

--Toll_Free

 

[smokercraft]

Yagi reflector/ quad reflector

Boy, I get off the computer for a few days and this subject just explodes.This is great all the big antenna minds in one spot,who could ask for anything more.I would like to thank everyone for their input.Tollfree, I have studyed the quagi some, but I would like to stay with both h/v polarization.I talk to allot of mobiles and just horizontal makes it tuff.Thanks jay for the info, I to went up on the boom size to 1 3/4 and had some new hubs made.Got all new stainless steel hardware and new gammas, I think I will just put her back together stock and see how it flys. I am going to build another four element quad, and I am going to adapt the old hy-gain big gun feed system,making the parts for it now.Like I said, sometimes I just play way to much.Thanks again, this has made for some very interesting reading