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  #1 (permalink)  
Old 09-12-2018, 8:47 PM
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Default Anyone See This?

New SW antenna on Universal's online catalog.

https://www.universal-radio.com/cata..._ant/4873.html
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Old 09-12-2018, 9:58 PM
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Interesting. Says it's a passive antenna, but "which includes magnetic-field-enhancement". Not sure i totally understand the principle or the price.
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Old 09-12-2018, 10:43 PM
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Magnetic field enhancement? Probably a ferrite core.

I once experimented with a large ferrite rod with a coupling loop wrapped around it, as a low noise receiving antenna. Picture a large loopstick with the primary tuned winding removed.

It actually worked pretty good. I'm wondering if this is something similar. Basically a coupling loop to capture the magnetic component of a signal.
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Old 09-12-2018, 10:49 PM
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The inventor of this antenna makes some wild claims about some of his other antennas, which I own and they do not match his claims. He seems to sell himself as a Phd in electronics/antenna theory but he's actually a low level medical doctor of some kind. That might explain why he only has a tech class ham license.
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Old 09-12-2018, 10:55 PM
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Oh, ok, i can see that. i was thinking something along the lines of a small barrel configuration of ferrite rods i had seen in the past.
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Old 09-12-2018, 11:55 PM
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Quote:
Originally Posted by prcguy View Post
The inventor of this antenna makes some wild claims about some of his other antennas, which I own and they do not match his claims. He seems to sell himself as a Phd in electronics/antenna theory but he's actually a low level medical doctor of some kind. That might explain why he only has a tech class ham license.
You just saved me $100 (actually, I wasn't going to get this anyway...)
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Old 09-13-2018, 12:51 AM
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Quote:
Originally Posted by prcguy View Post
The inventor of this antenna makes some wild claims about some of his other antennas, which I own and they do not match his claims. He seems to sell himself as a Phd in electronics/antenna theory but he's actually a low level medical doctor of some kind. That might explain why he only has a tech class ham license.
Some pretty unflattering words for Doctor Jack. How well do you know Jack?

I met him 30 years ago when he attended the ham radio class I was teaching and passed. And has done well with his life.

So, you don't like his antennas. Just say that and be done with it.

Larry
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Old 09-13-2018, 2:10 AM
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Low level Doctor. Spend 12+ years in school after high school and then you can call someone a low level doctor.......
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Old 09-13-2018, 3:13 AM
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I'd like to see the coax common mode choked please. Hard to do on that magmount at the feedpoint unless you hack it.

I get PLENTY of signal from my loop wires that are entirely on the ground. Choke that thing.

Unless one wants to listen to near-field magnetic components that are less than 1/20th wavelength away, anything beyond your backyard is definitely far field, and no matter the antenna, it is the E field, not the magnetic that drives it.

Be very careful here. Anyone remember the CFA / EH antenna. I don't know if that is the principle here, but this is good reading for that type of antenna:

http://www.w8ji.com/e-h_antenna.htm

I'm still open to it, but "proprietary" antenna engineering kinda raises my inner skeptic. I'd like more details.

Last edited by hertzian; 09-13-2018 at 3:24 AM..
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Old 09-13-2018, 3:20 AM
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Originally Posted by hertzian View Post
I'd like to see the coax common mode choked please. Hard to do on that magmount at the feedpoint unless you hack it.

I get PLENTY of signal from my loop wires that are entirely on the ground. Choke that thing.

Unless one wants to listen to near-field magnetic components that are less than 1/20th wavelength away, anything beyond your backyard is definitely far field, and no matter the antenna, it is the E field, not the magnetic that drives it.

Be very careful here. Anyone remember the E-H antenna. Uh huh.

A dangerous topic, as 20 years of usenet bickering about "shielded loops" responding to the magnetic field turned out to be false for anything worth listening to beyond your shack.

I'm still open to it, but "proprietary" antenna engineering kinda raises my inner skeptic.
Brilliant!
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Old 09-13-2018, 3:33 AM
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Yikes - that was fast. I edited it to include W8JI's view on CFA / EH antennas. Not sure if that is similar to what is being designed here, but I'd like a closer look.
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Old 09-13-2018, 3:38 AM
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Well, i enjoy your "grip" on antennas. Your views and reviews are based on field activity not armchair arguments.
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Old 09-13-2018, 9:44 AM
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Maybe Dr Jack is a real nice fellow, I'll take your word for it. Otherwise I have a real problem with antenna companies that use snake oil tactics to advertise their products and MP Antenna, Nil-Jon and other companies associated with this nice fellow fall into that category.

I read a report that I'm trying to find again where a company bought one of his new Wi-Fi antennas based on the wild claims. Jack showed up himself to install it and according to the report he had basically no clue on the installation basics and when it was finally installed and working it performed much worse than what it replaced. It was reported that Jack kept babbling about it must work better because of some mumbo jumbo techno babble, but in the end it was a complete failure. I think it left the person who witnessed all this was bewildered that the guy who supposedly invented the thing seemed to have little knowledge at all about antennas.

You can read endless comments from actual antenna engineers who have watched his Youtube videos and the comments about the techno babble are quite funny. He might fool a few people with that but eventually it catches up.

I bought a Super-M Ultra base antenna (rated 25MHz to 6GHz) to test and can tell you first hand what a dog it is and so far it does nothing that any sub $50 Discone can't do. In fact, I was recently using it in the 800-900MHz band where I took some measurements of known signals with an HP Spectrum Analyzer , quickly swapped it for a Maxrad Discone made for 300MHz to about 2.4GHz and the Maxrad pulled in the same signals right around 10dB better.

I also tested the Super-M Ultra in an area with hills and lots of non line of sight where its supposed to shine and a RS Discone provided the same if not better performance at a fraction of the cost. The Super-M Ultra is also poorly designed for long term use outside with some bare aluminum parts that start corroding quickly, especially with a bunch of recessed set screws pointing straight up to catch and hold water to aid the corrosion process. And an O ring failed causing an intermittent connection to the cheap NMO base station adapter. That base station NMO mount on the Super-M Ultra looks to be good to about 500MHz but his entire antenna is rated to 6GHz? How does that work?

So you enjoy your personal quality time with Jack as I suspect you have never paid money for any of his products, otherwise you might have a few different things to say.


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Originally Posted by N8IAA View Post
Some pretty unflattering words for Doctor Jack. How well do you know Jack?

I met him 30 years ago when he attended the ham radio class I was teaching and passed. And has done well with his life.

So, you don't like his antennas. Just say that and be done with it.

Larry
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Old 09-13-2018, 5:09 PM
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Actually have the 145/220/440 MHz mobile antenna. It works as good as any Larsen dual band I've ever had, and any other branded antenna/antennas.

But, would I buy that for shortwave, most likely not. I prefer something that would be a 'bit' bigger.

Larry

Last edited by N8IAA; 09-13-2018 at 5:14 PM.. Reason: additional
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Old 09-14-2018, 8:25 AM
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Someone posted a review on the VHF/UHF fat stick antenna that was favorable (possibly you) but a later review said the current model does not perform as well as the original. I was going to try one of these until I read the later review. If the original worked ok I wonder why it was changed for the worse?


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Actually have the 145/220/440 MHz mobile antenna. It works as good as any Larsen dual band I've ever had, and any other branded antenna/antennas.

But, would I buy that for shortwave, most likely not. I prefer something that would be a 'bit' bigger.

Larry
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Old 09-14-2018, 6:45 PM
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I went on the website and watched some videos demonstrating this compact SW antenna. Three tests were shown comparing against the portable's whip. Lower noise for sure but not exactly digging out even moderately tough signals, two were religious stations out of Tennessee and the other was China's flamethrower. I'll wait until they start turning up on eBay in a few years for 1/10 the price before I actually try one.
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Old 09-17-2018, 12:14 AM
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As a apartment dweller, I am space restricted. Landlord is extremely cool, but there just is not the room for anything full sized below 2 meters. Was looking at his 28-450 antenna as a compromise and spoke to several folks at Universal Radio who have sold quite a few and state grounding (duh) is key to optimal operation.

Think I will save my $$ and work on building a hidden exterior dipole for 6 meters.

I bought a Nil Jon several years back and installed it center roof mount on my Escape. Excellent performance, but the wind resistance tends to bend the aluminum elements some. Removed it and went with a old school quarter wave to monitor UHF.
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Old 09-17-2018, 2:44 PM
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Think I will save my $$ and work on building a hidden exterior dipole for 6 meters.
Bravo, thinking critically can guide you toward a favorable result. A bit of wire outdoors, a proper balun, coax/feedline and a passive tuner can provide happiness on RX. (One may quickly learn that AM and or FM band filters inline can prove quite helpful.)

I would enjoy a website that provides results of antenna testing and comparison. From a general frequency sweep to analysis of RX, and TX if applicable. An effort similar to Sherwood Engineering, but for antennas.
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Old 09-17-2018, 7:35 PM
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Please, guys, let's not wander - this forum is for antennas BELOW 30 Mhz. 'Nuff said.

Loops are a much better bet in space-tight areas...instead of this (possibly) snake oil found in the first message...Mike
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