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Old 2011-03-22, 02:08 AM   #1
300ohm
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Default Mohu Leaf Omni-directional OTA Antenna

Heres a new interesting (uhf-vhf-hi ?) indoor antenna claiming to be omni-directional and claims to get about 8% more "Relative Signal Strength" than the C1.
http://www.gomohu.com/free%20tv%20-%...0antennas.html

I take it that since they dont post gain numbers, it has less gain than a C1, which makes sense as an omni-directional.

I originally thought it was a typical gimmicky type antenna until I looked at the parent company.
http://www.greenwavescientific.com/

It seems the Mohu Leaf is a take off of the "Mud Flap" antennas of their line.
http://www.greenwavescientific.com/d...20Antennas.pdf

The datasheet does show interesting gain patterns compared to a standard whip antenna. A standard whip antenna may be around 3 to 6 dBi or so.
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Old 2011-03-23, 01:07 PM   #2
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This "IS" a very interesting antenna . Afriend of mine from London Ont. has been driving me nuts lately to build her an indoor apartment antenna for her new HDTV . I was stumped on what to build her till I saw this .
Thanks 300ohm .
Taking the dimensions in the specs, I began playing around with it on Nec . You can really change the patterns easily throughout the frequencies and achieve a nice omni pattern by playing around with the hieght and width . I opted to stay mostly directional for her window faces towards the London towers and I ended up with 8" square , 1" feedpoint in middle of the antenna.



The SWR is alittle high but I`m sure the experts could fix that. So going by my figures and using the Loss formula it would be a pretty low gain antenna. However this is only meant to pick up stations less than 8 miles.
VHF showed extremely high SWR.



So with some time to kill and less than 40" of 1/4" solid alum. I bent one up , drilled two holes , put in 2 brass #6 bolts and 4 nuts for a balun. Very cheap.
Nice flat antenna that you could cover with endless ideas .
For the heck of it I hooked it up to the LG , hung it in the window , @ 10 off the ground, through obstructions , I was impressed with what it picked up . Highlighted below is what it recieved. most signals were pretty snowy but was there.



31 & 10 (VHF) I could get perfect picture . I only have 1 digital avail. but couldn`t get it. This coming weekend will tell how it does in the city.
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Old 2011-03-23, 01:44 PM   #3
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To determine how OMNI it really is, change from "Total" to "Horiz" polarization display.....
and/or provide the Horizontal Polarization (vice Total) Azimuthal Pattern charts at low, mid & high freqs.
It just might have a significant Vertical Polarization response, helping to fill in the OMNI pattern.....
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Old 2011-03-23, 02:17 PM   #4
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Here are the patterns at 600Mhz. Thats when it gets Omni with these dimensions . You can get this pattern at a lower frequency using different dimensions. Thats what is so nice about 4NEC2 , you can easily make changes to suit ones needs.
These are top views looking down.

Hor-gain



Ver-gain



Tot-gain

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Old 2011-03-24, 11:11 AM   #5
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Lovota,
Low gain is not a concern because it's omni, and it can always be amplified.
Does this cover the entire UHF 14-51 bandwidth evenly? Any VHF gain? I seem to recall with the SH you found that the feed gap helped with lowering SWR.
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Old 2011-03-25, 09:23 AM   #6
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Some designs hold a nice constant pattern throughout the UHF band and some change alot . This one changes alot. Similar to how the Stealth Hawk reacts as you rise in frequency . Instead of this one going to multi lobes it goes from bi-directional front - back to bi-directional side - side and omni- directional inbetween . You can change the frequency at which it is omni for eg. If I was to make it 2" wider, my 600Mhz pattern will be moved down to 500Mhz and anything above will have the pattern off the sides , below is front to back .
This is due to what "holl ands" was hitting on in regards to horizontal and vertical gain patterns. With this 8" square loop at 470-600Mhz it is mostly horizontal gain and very little vertical. Above this frequency it flips to the opposite . Lots of vertical , little horizontal gain.
I found a 1" feedpoint was the magic number for SWR.
On this loop the VHF pattern was out the bottom with an extremely high SWR. With Nec , opening the top dropped the SWR inhalf but still high. Removing 4" from the middle of the top wire was optimum for forward pattern. Like a dounut standing on its side.
Now the pattern throughout the whole UHF band with this open top was constantly off the sides but a nice wide pattern at that. I liked it.
Modelling shows VHF as terrible but when I stuck it in my window it picked up some VHF very good.
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Old 2011-04-01, 11:03 AM   #7
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Finally tested the 8" Square Loop in London. Picked up the top 9 stations in the below TVFool plus it had singal on CKCO 13 , pretty fuzzy but was there . All other channels were perfect except CityTv 31 has a bit of ghosting .



Not bad for a 4th floor window surrounded by other tall buildings .



I used 1/2 of a .50 cent pc of bristal board to fold around the element .
Used a small piece of plexy to hold the feed at 1" .
Nice little $4 antenna . Then add your balun & cable .

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Old 2011-05-05, 12:50 AM   #8
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Any more real life user evaluations of the Mohu leaf antenna ?

On another forum, a user on Long Island reported getting NO stations with it, while his TVFool report showed NMs in the 30-40's and at least one above 50 NM. He should have gotten that station at least with a paper clip antenna. I suggested to him that the unit was probably defective with a short at the F connector, but he said he would just get a refund and not replace it with another to test.
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Old 2011-05-21, 08:40 AM   #9
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Default LOVEOTA

Have you tried to model and build a double MOHU LEAF? Since it is so small and compact at 8" it would be interesting to see what the results would be if you were to stack 2 of them vertically or horizontally side by side.

I don't think these would be of any benefit for me given my terrain and distance to the transmitters but since I have lots of leftover wire from my building GH antennas I might make one of these as they are so simple.
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Old 2011-05-22, 08:30 PM   #10
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No I haven`t messed with stacking or ganging of this model. It doesn`t have the bandwith to be worth while . I`ve scaled it up and made changes to get the best out of this style but nothing great became of it. I`d sure be interested in seeing what wire pattern was used in the original (post#1). If your looking to try something new with that extra wire, in my profile I have my SR6 Quad that packs a nice punch for its size . So far its proving out good.
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Old 2011-05-23, 08:55 AM   #11
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Default SR6 Quad

Thanks LoveOTA! Looking it over and I might just give it a try!
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Old 2011-06-15, 04:39 PM   #12
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I know there's not been any action on this thread since May, but I thought I'd post my results with the Mohu Leaf vs. the Winegard FV-HD30 FreeVision. Both are marketed as indoor antennas, but the Winegard can be mounted outside. The test configurations for both were exactly the same position mounted on a wall of a 2nd story bedroom of our house. Approximate height above ground is 18 feet.

I'm in a 150K population city, but typically can only receive 2 to 4 stations with only rabbit ears/circle UHF antenna. The Leaf captures 12 stations - 11 UHF and 1 VHF-Hi DTV station. The same for the FreeVision. However, there is more blocking and fallouts with the Leaf than with the FreeVision.

Overall, the Leaf is pretty impressive given its extremely stealthy footprint. Of course, a direct comparison of the respective signal strength for each received channel is the best comparative method, and I may post these results later.
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Old 2011-08-28, 11:34 AM   #13
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Thumbs up The Leaf

I have Winegard SS-3000 Amplified Indoor UHF/VHF Antenna on my kitchen and bedroom TVs. Bedroom it has done fine just need to adjust its direction to watch channel 7 and 11 but in the kitchen it never did better than channel 2 - 9. I heard about the Leaf and found it looked pretty unimpressive but figured why not give it a shot. So I ordered one, watched the video on You Tube on how to hook it up which you have to follow closely because it makes a difference how it's placed. Used tape to hold it to the wall so I can move it around and gave it a try. From the first spot tried it grabbed 24 stations more than twice what the Winegard did. I needed to move it around a few time but now, "WOW" I got 34 stations. Not only 2-9 but 11,13 which I haven't seen since analog broadcast ended with a whole bunch of new channels. Don't ask me what makes the Leaf so much better than the Winegard SS-3000 Amplified Indoor UHF/VHF Antenna but it blows it away. With the Leaf I found inches makes a difference with reception so don't move it too far around when finding a spot for reception. Also don't position it on its side like the instruction says, follow its positioning closely and you will find this paper thin unimpressive looking antenna is truly impressive, well worth the cost. Oh i forgot to point out i'm around 13 miles from NY City in the glid path for JFK and i'm finding the Leaf isn't effected much by over flying planes or bad weather like the Winegard is. The Leaf held all the stations in the storm we just had also.
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Old 2011-08-28, 11:42 AM   #14
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dagger666 please post your TVFool report so that we have better information for understanding your results.
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Old 2011-10-13, 05:22 PM   #15
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Here's an interesting video about the mohu flat panel antenna.
note: freeze the video at 10 seconds to see the metallic tape layout
http://www.youtube.com/watch?v=sZFjYiZMNhI

Quote:
Paper Thin Leaf Indoor HDTV Antenna - Made in the USA!
RCA AMP1450R Digital Amplifier for Indoor Antenna
Wall-Tenna - Proudly Made in USA
Supersonic SC-607 Flat Digital HDTV Antenna With VHF and UHF Frequency Range
From what specs I can find it's 5dbi max! Channels 7-13 & 14-69

Judging by 'my hand' size, I'd guess it's about 14" x 21"
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