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Author Topic: MFJ 10 meter Moxon Rectangle  (Read 2322 times)
AF5C
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Posts: 123




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« on: November 13, 2012, 10:49:03 AM »

I see that MFJ has come out with a 10 meter Moxon Rectangle antenna.  I like the price on it-$75 at R and L Electronics.  I like the size and weight, would fit nicely in my setup.  However, MFJ's ad says the gain is 3.3DBi.  That put it at .5 db gain over a dipole or something like that.  Is that really worth it for the price.  Yes, it has some F/B to it, but would it be worth the money over the G5RV I am currently using on 10m?

John AF5CC
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NU1O
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Posts: 2594




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« Reply #1 on: November 13, 2012, 11:04:53 AM »

If MFJ is selling something for $75 one could probably build a better equivalent antenna for less than $10.  Aside from no gain I would check the power limit in case you run an amp.

Let me be upfront and state I am no fan of MFJ.  They do fill a niche by selling products some hams might not be able to afford elsewhere but much of what they sell actually is junk.

73,

Chris/NU1O

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N3QE
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Posts: 2074




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« Reply #2 on: November 13, 2012, 11:31:34 AM »

Well your G5RV probably has some gain too, just at completely random angles.

Len Cebik used to have some really good NEC plots of Moxons on his webpages but that now costs big bucks to access.

The point is, the Moxon has excellent front to back ratio, so is great at reducing noise from all the other angles on receive too.
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N4OGW
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Posts: 285




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« Reply #3 on: November 13, 2012, 12:18:33 PM »

I believe that should be 3.3 dBD, I assume 3.3 dB over a dipole in free space.

MFJ has it listed as a "Moxom" on the website Smiley

Tor
N4OGW
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KY6R
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Posts: 3133


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« Reply #4 on: November 13, 2012, 02:21:02 PM »

Moxon's have the same gain but better F/B than a 2 element yagi when compared at the same height above ground.

Depending on how they are built - they can have 3.5 dBd gain - maybe a little more.

I am building a 15M Moxon out of aluminum and will mount it 35' above ground.

Rich
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WB3BEL
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Posts: 77




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« Reply #5 on: November 14, 2012, 07:14:51 AM »

Well your G5RV probably has some gain too, just at completely random angles.

Len Cebik used to have some really good NEC plots of Moxons on his webpages but that now costs big bucks to access.

The point is, the Moxon has excellent front to back ratio, so is great at reducing noise from all the other angles on receive too.

Actually it does not cost anything to access cebik.com....You just have to register...and re-register every year...
It's a pain but worth it.  You just have to live with some adverts from Antennex.  use a throwaway webmail account and enjoy...

Moxon has great F/B but actually less F/R so it reduces signals 180 degrees off the boresight better, but at other back angles less.  If you model the antenna, you will see the RDF of the 2 ele yagi is better something approaching 7 dB is possible where the Moxon yields 6 dB.  In many situations the interference and noise suppression of the standard 2 el Yagi is superior. 
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WB3BEL
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Posts: 77




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« Reply #6 on: November 14, 2012, 07:19:39 AM »

Moxon's have the same gain but better F/B than a 2 element yagi when compared at the same height above ground.

Depending on how they are built - they can have 3.5 dBd gain - maybe a little more.

I am building a 15M Moxon out of aluminum and will mount it 35' above ground.

Rich

Actually a standard 2 ele Yagi can have higher gain than Moxon.  They are close. 

F/B can be fantastic on Moxon.  But F/R is better on Yagi.

The main advantage of the Moxon is small size.  Also they can be made from wire at low cost.  Maybe they can be more lightweight...In most other ways a standard Yagi is superior. 

But a half decent Moxon can be a big step up from a non-directive wire antenna.  It is amazing at what a few dB of gain and some interference suppression will do to help work more DX.  Many first time beam users are shocked at how much better a small simple beam will work
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W1NK
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Posts: 426


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« Reply #7 on: November 14, 2012, 08:16:34 AM »

Quote
Actually it does not cost anything to access cebik.com....You just have to register...and re-register every year...
It's a pain but worth it.  You just have to live with some adverts from Antennex.  use a throwaway webmail account and enjoy...

Unfortunately it now costs the price of a subscription to AntenneX ($41.97/yr) to obtain "free" access to Cebik.com.  Without the subscription, it's $29.95/yr to access the site. It's all explained here:
http://www.cebik.com/lbc_signup.htm

Frank, W1NK
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KY6R
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Posts: 3133


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« Reply #8 on: November 14, 2012, 08:23:25 AM »

Moxon's have the same gain but better F/B than a 2 element yagi when compared at the same height above ground.

Depending on how they are built - they can have 3.5 dBd gain - maybe a little more.

I am building a 15M Moxon out of aluminum and will mount it 35' above ground.

Rich

Actually a standard 2 ele Yagi can have higher gain than Moxon.  They are close. 

F/B can be fantastic on Moxon.  But F/R is better on Yagi.

The main advantage of the Moxon is small size.  Also they can be made from wire at low cost.  Maybe they can be more lightweight...In most other ways a standard Yagi is superior. 

But a half decent Moxon can be a big step up from a non-directive wire antenna.  It is amazing at what a few dB of gain and some interference suppression will do to help work more DX.  Many first time beam users are shocked at how much better a small simple beam will work

I've modeled both a 2 element yagi and 2 element aluminum Moxon and don't see a 1 dBd improvement one over the other - at least not in forward gain. I do see an improvement with the Moxon in F/B, and on the order of 5 - 6 dB.

But I will see if I can get that extra dB out of the standard yagi over the Moxon.

The 2 element yagi is easier to build - as there is no "gap" to worry about getting right and ensuring that the gap and associated wires or aluminum don't move around in the wind.

I've always thought the best you could get out of a 2 element yagi was 4.1 dBd - with about 10 dB F/B and 4.1 dBd on the Moxon with 15 or more F/B.

Rich
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WB3BEL
Member

Posts: 77




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« Reply #9 on: November 14, 2012, 08:31:03 AM »

Quote
Actually it does not cost anything to access cebik.com....You just have to register...and re-register every year...
It's a pain but worth it.  You just have to live with some adverts from Antennex.  use a throwaway webmail account and enjoy...

Unfortunately it now costs the price of a subscription to AntenneX ($41.97/yr) to obtain "free" access to Cebik.com.  Without the subscription, it's $29.95/yr to access the site. It's all explained here:
http://www.cebik.com/lbc_signup.htm

Frank, W1NK

Frank,
You are right..

This is all very sad...ANTENNEX steals LB's material...Now they are charging for it.

SAD SAD SAD....Well I am sure it will all come back to them in the long run...
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KY6R
Member

Posts: 3133


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« Reply #10 on: November 14, 2012, 08:41:29 AM »

Moxon's have the same gain but better F/B than a 2 element yagi when compared at the same height above ground.

Depending on how they are built - they can have 3.5 dBd gain - maybe a little more.

I am building a 15M Moxon out of aluminum and will mount it 35' above ground.

Rich

Actually a standard 2 ele Yagi can have higher gain than Moxon.  They are close. 

F/B can be fantastic on Moxon.  But F/R is better on Yagi.

The main advantage of the Moxon is small size.  Also they can be made from wire at low cost.  Maybe they can be more lightweight...In most other ways a standard Yagi is superior. 

But a half decent Moxon can be a big step up from a non-directive wire antenna.  It is amazing at what a few dB of gain and some interference suppression will do to help work more DX.  Many first time beam users are shocked at how much better a small simple beam will work

AHA - I was just able to get almost that 1 dB extra gain on a 2 element 15M yagi over the Moxon, but at the expense of F/B.

Take a look at my QRZ.COM page - I have just stacked 2 17M 2 element yagi's - and for my QTH and its limitations its amazing what a stack of two 2 element yagi's will do.

I am cutting and drilling aluminum tonight - and will now probably just go for a 2 element yagi up 35' for 15M instead of the aluminum Moxon. 2 element yagi's are dirt simple to build and put up - and in my opinion are better than any trapped tri-bander once you factor in the compromised element spacing and trap loss.

Lets put it this way - I would bet a set of 3 2 element mono band yagi's for 20, 15 and 10M - each at > 1 wl high will out perform a trapped tribander at a height of say, 45'.

I can confirm that a stack of two 2 element mono banders separated by 1/2 wl and matched through a STackmatch II crushes the tribander - and is the equivalent of at least a 4 element mono bander, maybe even a 5 element monobander.

Rich
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NU1O
Member

Posts: 2594




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« Reply #11 on: November 14, 2012, 09:12:42 AM »

Lets put it this way - I would bet a set of 3 2 element mono band yagi's for 20, 15 and 10M - each at > 1 wl high will out perform a trapped tribander at a height of say, 45'.

I can confirm that a stack of two 2 element mono banders separated by 1/2 wl and matched through a STackmatch II crushes the tribander - and is the equivalent of at least a 4 element mono bander, maybe even a 5 element monobander.

Rich

First of all, you don't bet unless you've recently changed your policy.   Wink  It's a nice theoretical discussion but few hams will be able to put up 3 monobanders each separated by 5 meters unless they can rotate their tower in which case they will not be bothering with 2 element Yagis.

73,

Chris/NU1O
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KY6R
Member

Posts: 3133


WWW

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« Reply #12 on: November 14, 2012, 08:14:17 PM »

Lets put it this way - I would bet a set of 3 2 element mono band yagi's for 20, 15 and 10M - each at > 1 wl high will out perform a trapped tribander at a height of say, 45'.

I can confirm that a stack of two 2 element mono banders separated by 1/2 wl and matched through a STackmatch II crushes the tribander - and is the equivalent of at least a 4 element mono bander, maybe even a 5 element monobander.

Rich

First of all, you don't bet unless you've recently changed your policy.   Wink  It's a nice theoretical discussion but few hams will be able to put up 3 monobanders each separated by 5 meters unless they can rotate their tower in which case they will not be bothering with 2 element Yagis.

73,

Chris/NU1O

Few people would take on such a project - that's true. But for those with an AB-952, AB-577 or similar, this is one hell of a fun project.

Check out my QRZ.COM page for pictures and the whole story. It has evolved in the last 3 weeks that I have been cutting and drilling and guying this crazy thing.

The moral of the story is that you can get 5 or 6 element mono band yagi performance - plus compressed lobes and a quieter antenna by stacking smaller, 2 element yagis than putting up a monster tower and monster rotator and all of that associated cost.

More importantly, I get the satisfaction that not only did I build it - but I also designed it.

Then - when I retire to Bend, Oregon in 10 years - I will take it with me. My 55' tower fits in the back of my BMW X3 . . . .

No permits, no concrete footings, no hearings, and a teeny tiny fraction of the cost of buying massive boatloads of stuff.

To each his or her own - we all get to play it the way we like.
« Last Edit: November 14, 2012, 08:53:59 PM by KY6R » Logged
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