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!
Thanks!
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
quad reflector versus yagi reflector
- Thread starter smokercraft
- Start date
reflector
C2, that is my thinking to, I believe that is how I will build it.I have a tilt over tower if I want to change it,I some times play way to much.I was really hoping for a little more input on this from the antenna guys on here.Well I am off to do some wrenching. Thanks!
C2, that is my thinking to, I believe that is how I will build it.I have a tilt over tower if I want to change it,I some times play way to much.I was really hoping for a little more input on this from the antenna guys on here.Well I am off to do some wrenching.
Thanks!Toll_Free
Well-Known Member
smokercraft said: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.
If you do some research, you will find out the quadreflector and driven with a yagi director assembly is the best way to go.
It's the laws of inverse reciprocity (if memory and spelling serves me correctly).... Think of it this way... You have 36 feet of driven element vs. 18 feet on a yagi.
What's going to get more signal out there and receive more.
And the other gentleman was right. The antenna rejection kit was a bs item sold by snake oil salesmen to detune your antenna.... Err make it better
So basically, to answer your question, a quad reflector is best, with a quad driven element, with yagi directors.
Get another reflector assembly and make it smaller
--Toll_Free
Then, does that mean that a 1/2 wave length driven element is less of a radiator than a full wave driven element? That longer driven elements are better than shorter driven elements? Bigger antennas are better than smaller antennas?
The "laws of inverse reciprocity". Would you tell me what that means? I do have to admit it's the absolute best one I've heard in years. I love it!
- 'Doc
The "laws of inverse reciprocity". Would you tell me what that means? I do have to admit it's the absolute best one I've heard in years. I love it!
- 'Doc
Sounds like a quagi...
Would it not be even better to use all quad elements?
Maybe even best to make the elements circular?
But in the context of the MR4, is the reflector really a "quad" element, or is there just an extra piece of wire going around the reflector elements?
Would it not be even better to use all quad elements?
Maybe even best to make the elements circular?
But in the context of the MR4, is the reflector really a "quad" element, or is there just an extra piece of wire going around the reflector elements?
Toll_Free
Well-Known Member
W5LZ said:
Are you honestly going to post your callsign and ask questions like that?
Or are you one of those people that thinks a 19 inch antenna that has a loading coil to make it resonate will radiate a signal as well as one with a quarter wave, half wave or full wave radiating element?
W5LZ said:
In an ideal world, yes. However, there comes time when the high angle of radiation of say, a quarter wave, might be more benificial to you than the radiation pattern of say, a .64 wave.
The longer an element is, and it is made resonant, the better it will radiate. Conversely, it should increase the received signal at the feedpoint.
This is a generalization, and doesn't take into account that you might want a skewed pattern for your own reason.... But, I don't think anyone out there will argue that a short antenna is a better radiator than a long antenna..... not for general purpose comm's.
<<notice he omits the last part of that sentence.... The entire sentence reads"W5LZ said:
It's the laws of inverse reciprocity (if memory and spelling serves me correctly)...." <==---- I was wrong in the terminology, but close.....: law of reciprocity was the term I was looking for.
Tell ya one better.
C.-T. Tai, "Complementary reciprocity theorems in electromagnetic theory," IEEE Trans. Antennas Prop. 40 (6), 675-681 (1992).
Or, here ya go:
"Reciprocity
So far we have been talking mostly about receiving antennas. Fortunately there is a "law of reciprocity". It turns out that antennas behave in exactly the same way whether transmitting (that is launching energy into electromagnetic waves) or receiving (extracting energy from electromagnetic waves). We can define the gain of a transmitting antenna as the ratio of the power radiated in a specific direction to the power that would have been radiated had it been radiated uniformly in all directions (isotropic radiation). The peak gain of an antenna is called the directivity. The effective area of a receiving antenna as a function of direction is directly proportional to the gain of the same antenna when used as a transmitter. The effective area is also another performance parameter of antennas."
Directly stolen from http://www.searfe.atnf.csiro.au/documentation/bg_antennas.doc
If your the lazy type, then try this link...
http://www.google.com/search?client...nnas&sourceid=opera&num=100&ie=utf-8&oe=utf-8
Care for more?
Take care.
--Toll_Free
<believes he got the html formatting correct.
Toll_Free
Well-Known Member
C2 said:
Exactly what it is. I was researching antennas about a week ago, actually, since I'm starting from scratch again. So far, the quagi seems to be beating everything else from what I've read.....
As to making elements circular, I wouldn't do that. Circular elements would be circular polarization. Set a quad up correctly (orientating the feedpoint) and you can arrange for either horizontal or vertical polarization. Then, arrange your directors the same.
Makes sense, if ya really think about it. I'll be playing with ideas once some aluminum becomes available around here.
--Toll_Free
[quote="Toll_Free]Circular elements would be circular polarization.
--Toll_Free[/quote]
I don't know if I believe that.
How about a pentigon element?...hexagon, octagon...?
freecell would be pleased
http://www.signalengineering.com/ultimate/circular_polarization.html
--Toll_Free[/quote]
I don't know if I believe that.
How about a pentigon element?...hexagon, octagon...?
freecell would be pleased
http://www.signalengineering.com/ultimate/circular_polarization.html
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. When you get right down to it, the radiation patterns aren't all that different either.
A 1/2 wave element is no more 'resonant' than a full wave, and visa-versa. It's either resonant or it isn't.
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? 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.
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
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. When you get right down to it, the radiation patterns aren't all that different either.
A 1/2 wave element is no more 'resonant' than a full wave, and visa-versa. It's either resonant or it isn't.
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? 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.
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
Toll_Free
Well-Known Member
Highlander_821 said:
It's as true as I could get in generalizing the thread as much as possible.
No, to get true CP, you need to have an antenna wound in a helix fashion.... And then the direction of the twist also dictates whether it's rhcp or lhcp.
Again, it was a generalization......
--Toll_Free