Stupidfatkid
Member
Any one have real-world experience with this antenna? Some of the inventor's claims seem to be a little overly optimistic.
COMPACTenna V.U.7/800
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COMPACTenna V.U.7/800
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COMPACTenna V.U.7/800
- Thread starter Stupidfatkid
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The inventor looks like the guy in that Pink Floyd, Up Against the Wall video.
Grab one and let's see but I'm afraid it's probably just this.
Grab one and let's see but I'm afraid it's probably just this.
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Stupidfatkid
Member
No problem. I'll order one. Heck, I'll order two. One for both of us. I'll just need to borrow your credit card.
It's 2.0 dbi which is actually .5 dbd so unity gain. It would be nice for the 3rd brake light mount on the jeep though.
I haven't been able to find any reviews of this antenna. It's a bit pricey to just buy one for a test. The specs are not exciting gain wise, but what would you expect. It does seem to offer flat response. In reality it seems to be similar to a good on scanner antenna with a NMO mount and a rugged outer covering. In 46 years of scanning I've seen many antennas that claim radical designs, but end up no better than anything else. If you want a good performing and reasonably compact mobile antenna, I've had good luck with the Austin Spectra. Here in California I need 42Mhz coverage for the CHP and the Austin has been as good or better than others.
I watched the first few minutes of the technical explanation and my BS detector is on high alert.
mmckenna
I ♥ Ø
A 50Ω dummy load will have flat response across large portions of the band. It won't work worth crap, but you could easily sell it as a "compact wide band" antenna to the masses that will buy this sort of stuff.
And as was stated, 2dBi isn't good. Go back through hundreds of other posts where dBi and dBd are compared. Using dBi when most of the industry is using dBd is a way to artificially make it look better than it is
At that length, you'll do better with a basic 1/4 wave. At least it will be flexible and not shear off the mount if you hit something. A 1/4 wave 2 meter antenna has an impressive return loss plot across a large portion of the VHF band, no problem at all covering 144-170 range with a single antenna. Also, a 1/4 wave VHF antenna is going to be resonate at 440MHz. I used one for years with excellent results.
696-870? Useful for monitoring, but useless to the amateur radio crowd they are marketing this to.
No matter what anyone claims, antenna designs are governed by the laws of physics. No manufacturer, inventor or dealer has any sort of magic pixy dust they can use to make their antennas work outside the laws of physics.
$129? Go with the 1/4 wave VHF, at least you'll be getting real world gain number, flexible antenna, and if something does happen to it, you can replace it for less than $15.00.
And as was stated, 2dBi isn't good. Go back through hundreds of other posts where dBi and dBd are compared. Using dBi when most of the industry is using dBd is a way to artificially make it look better than it is
At that length, you'll do better with a basic 1/4 wave. At least it will be flexible and not shear off the mount if you hit something. A 1/4 wave 2 meter antenna has an impressive return loss plot across a large portion of the VHF band, no problem at all covering 144-170 range with a single antenna. Also, a 1/4 wave VHF antenna is going to be resonate at 440MHz. I used one for years with excellent results.
696-870? Useful for monitoring, but useless to the amateur radio crowd they are marketing this to.
No matter what anyone claims, antenna designs are governed by the laws of physics. No manufacturer, inventor or dealer has any sort of magic pixy dust they can use to make their antennas work outside the laws of physics.
$129? Go with the 1/4 wave VHF, at least you'll be getting real world gain number, flexible antenna, and if something does happen to it, you can replace it for less than $15.00.
Stupidfatkid
Member
I saw the dBi stat. If you watch the second video (Theory and Design) he explains his theory on gain as it relates to the design of the antenna. It starts around 9 minutes.
https://www.youtube.com/watch?v=Vo626X-0fXQ
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prcguy
Member
That's the Nil-Jon antenna guy and I've never been fond of their advertising claims. Otherwise I sampled parts of the video and somewhat agree with most things said. The thing that bugs me the most is the guy looks like David Bowie talking antenna Sh*t. Is he wearing lipstick??
I didn't seem to get much info on the antenna in question and most of the discussion seemed geared towards his older Nil-Jon antennas and the newer and waaaaay too expensive "Ultra Base" and "Ultra Mobile" antennas. Maybe the info was there but my spot checking missed it. Did I mention lipstick? Never mind....
prcguy
I didn't seem to get much info on the antenna in question and most of the discussion seemed geared towards his older Nil-Jon antennas and the newer and waaaaay too expensive "Ultra Base" and "Ultra Mobile" antennas. Maybe the info was there but my spot checking missed it. Did I mention lipstick? Never mind....
prcguy
mmckenna
I ♥ Ø
I watched most of it. Didn't see anything useful.
He did make some good points about how low gain antennas can outperform high gain antennas in some cases. The rest of it was pretty vague.
He did make some good points about how low gain antennas can outperform high gain antennas in some cases. The rest of it was pretty vague.
The second video is interesting and I could find nothing wrong with Nilsson's line of thought. Interesting concept of using the magnetic field to fill in the short term multi-path gaps, although as he points out it drops as a cube of the distance, as opposed to the square of the distance for the RF energy. For those of us out in the Stix where everything is DX I don't see that as useful. Unfortunately he stopped just before explaining how it works for either magnetic or diversity within the physical constraints of the tube.
I have problems getting my 1/4 wave VHF's under branches and my garage door- imagine the thump this one would make.
I am always amazed by the claims of antenna 'creators' who state that their design is superior to others because it looks like something out of a Buck Rogers movie. I am equally amazed that buyers fall for those claims for the same reason.
An antenna is really a very simple beast: a physical dipole (or electrical equivalent) that resonates at a particular wavelength (or multiple wavelengths) with RF energy to/from a particular polarization, azimuth and altitude, delivering the energy to/from a radio at a particular impedance. And in the case of a transmit antennas, handle the power from the PA without overheating or changing values. That's it in a nutshell, folks.
Bird roosts and futuristic gizmos gain nothing unless they really do concentrate more of the RF energy to/from the coax and in the direction you want it. And a 18" VHF whip on a magnet mount stuck to the top of a water tower connected to 125' of 7/8" low-loss coax will outperform a 'fancy' antenna on high loss RG-58. (Been there, done that after it hit the fan.)
Different antenna designs have different methods of creating a virtual dipole, either by incorporating it into the design or using the earth, car roof or structure for the 'other half' of the antenna. Changing the length of a whip or adding other elements cause the antenna to become directional or change resonate frequency(s).
RF energy is not created by an antenna, simply concentrated and/or directed. Coils and capacitance change the electrical length properties of a whip to accommodate size realities (as in CB antennas shorter than the 108" quarter wavelength). A simple 5/8 wavelength whip using the roof of a car as a ground plane creates harmonic waves (think of them as high and low pressure) that concentrate energy to/from the horizon and away from the birds and fish. Is is 3db gain (double the effective power), but only towards the horizon at the expense of elevation. If the target antenna is high, a 5/8 antenna may send all its energy underneath. A 1/2 wavelength whip antenna has about 1.5 times more horizontal gain than a 1/4 wave, and doesn't need a ground plane under it. A 3/4 wave whip has even more gain, but the energy is directed upwards and away from the horizon without a down-angled ground plane.
Ever cut a fiberglass gain antenna open ? No magic, just a series of resonate lengths of coax with the center and shield swapped at each junction. Gain by creating harmonic waves. Same applies to an antenna with external dipoles and a phasing harness. both create waves that direct energy in a useful direction to/from the horizon; higher gain creates a flatter bagel. Discone antennas have low gain but do work well for fixed locations as their physical design resonates at a wide range of frequencies. Mounting one on a car looks a little funky, even upside down.
Real world story: A boater bought a 21' 9db marine antenna from me to increase his range. He installed it himself, then called complaining his range was worse. When I went to look at the install I found that he had mounted the antenna leaning back at a rakish 45 degree angle to look cool. At that angle he could hit satellites in orbit ahead of him and fish in his wake, but little else. "Cool" was more important than reality. No wonder it didn't work.
A plain old quarter-wave on a car or 3db dipole array are hard to beat. I do have my own design which promises a 9dbZ gain over a quarter-wave at 10% of the length. (Note: 'dbZ' is a marketing, not engineering, value defined as the cube of my profitability over my cost of production.)
I have problems getting my 1/4 wave VHF's under branches and my garage door- imagine the thump this one would make.
I am always amazed by the claims of antenna 'creators' who state that their design is superior to others because it looks like something out of a Buck Rogers movie. I am equally amazed that buyers fall for those claims for the same reason.
An antenna is really a very simple beast: a physical dipole (or electrical equivalent) that resonates at a particular wavelength (or multiple wavelengths) with RF energy to/from a particular polarization, azimuth and altitude, delivering the energy to/from a radio at a particular impedance. And in the case of a transmit antennas, handle the power from the PA without overheating or changing values. That's it in a nutshell, folks.
Bird roosts and futuristic gizmos gain nothing unless they really do concentrate more of the RF energy to/from the coax and in the direction you want it. And a 18" VHF whip on a magnet mount stuck to the top of a water tower connected to 125' of 7/8" low-loss coax will outperform a 'fancy' antenna on high loss RG-58. (Been there, done that after it hit the fan.)
Different antenna designs have different methods of creating a virtual dipole, either by incorporating it into the design or using the earth, car roof or structure for the 'other half' of the antenna. Changing the length of a whip or adding other elements cause the antenna to become directional or change resonate frequency(s).
RF energy is not created by an antenna, simply concentrated and/or directed. Coils and capacitance change the electrical length properties of a whip to accommodate size realities (as in CB antennas shorter than the 108" quarter wavelength). A simple 5/8 wavelength whip using the roof of a car as a ground plane creates harmonic waves (think of them as high and low pressure) that concentrate energy to/from the horizon and away from the birds and fish. Is is 3db gain (double the effective power), but only towards the horizon at the expense of elevation. If the target antenna is high, a 5/8 antenna may send all its energy underneath. A 1/2 wavelength whip antenna has about 1.5 times more horizontal gain than a 1/4 wave, and doesn't need a ground plane under it. A 3/4 wave whip has even more gain, but the energy is directed upwards and away from the horizon without a down-angled ground plane.
Ever cut a fiberglass gain antenna open ? No magic, just a series of resonate lengths of coax with the center and shield swapped at each junction. Gain by creating harmonic waves. Same applies to an antenna with external dipoles and a phasing harness. both create waves that direct energy in a useful direction to/from the horizon; higher gain creates a flatter bagel. Discone antennas have low gain but do work well for fixed locations as their physical design resonates at a wide range of frequencies. Mounting one on a car looks a little funky, even upside down.
Real world story: A boater bought a 21' 9db marine antenna from me to increase his range. He installed it himself, then called complaining his range was worse. When I went to look at the install I found that he had mounted the antenna leaning back at a rakish 45 degree angle to look cool. At that angle he could hit satellites in orbit ahead of him and fish in his wake, but little else. "Cool" was more important than reality. No wonder it didn't work.
A plain old quarter-wave on a car or 3db dipole array are hard to beat. I do have my own design which promises a 9dbZ gain over a quarter-wave at 10% of the length. (Note: 'dbZ' is a marketing, not engineering, value defined as the cube of my profitability over my cost of production.)
mmckenna
I ♥ Ø
Seems to be what a lot of people are looking for. Image is more important than substance.
Yep, I've tried a lot of different antennas, and keep coming back to the quarter wave. My own personal experience, but they do tend to work best for my particular applications.
I like that idea. Variable Z comes in handy sometimes.
majoco
Stirrer
Um, er, yes, well.......
W5JCK
Member
This is basically a coil, a broomstick antenna design. Those terrible little dummy load of antennas on bubble-wrapped GMRS antennas are similar in design, and they are total trash. A broomstick design is basically a core (broomstick) on which you coil a wire. The idea is to increase the diameter of the antenna element from wire diameter to coil diameter. However, at the end of the day this antenna is less than unity gain and is little more than a shortened 1/4 wavelength tri-bander. You determine dBd by subtracting 2.15 from the dBi, so 2.00 dBi - 2.15 = -0.15 dBd = unity gain. As mentioned in an earlier post, SWR means little. You can tune an antenna to 1/1 and still not have a good radiation pattern. If you want a decent antenna then get one at a fraction of the cost for this garbage. And BTW, use of dBi for amateur radio antenna advertizing is very common, so always read the fine print. If you live in the boonies, then you need at least a 3 dBd gain antenna, and preferably more. That would be 3 dBd + 2.15 = 5.15 dBi or greater.
prcguy
Member
How do you know its just a big coil, did you see the insides? There are lots of antennas that look like a simple stick on the outside but inside they have stuff you've never seen before. One example I have is the First RF FRF-107 series that looks like a simple tube and some versions cover from about 100MHz to 6GHz with lots of clever patented antennas under the dome.
http://www.firstrf.com/products/
prcguy
http://www.firstrf.com/products/
prcguy
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prcguy's comment caused my brain recall these lyrics:
Ground Control to Major Tom
Your circuit's dead, there's something wrong
Can you hear me, Major Tom?
Can you hear me, Major Tom?
I would love a low profile antenna for my SUV that works well. Instead of crunching some numbers on antenna theory, I calculated the cost of Diamond NR770HB antenna and K9000LRMO motorized mount. While that pairing works for me for that particular vehicle, it may not be suited for others. Perhaps try a AZ504FXH first as it will flex and it is $100 less. The numbers look the same if that matters.
Ground Control to Major Tom
Your circuit's dead, there's something wrong
Can you hear me, Major Tom?
Can you hear me, Major Tom?
I would love a low profile antenna for my SUV that works well. Instead of crunching some numbers on antenna theory, I calculated the cost of Diamond NR770HB antenna and K9000LRMO motorized mount. While that pairing works for me for that particular vehicle, it may not be suited for others. Perhaps try a AZ504FXH first as it will flex and it is $100 less. The numbers look the same if that matters.
prcguy
Member
Not always, you can shorten a 1/4 wavelength vertical monopole element over a ground plane with a capacity hat to nearly 1/8 wavelength long overall with very little loss. If you go to maybe 3/8 wavelength long with capacity hat the loss is measured in tenths of a dB down from a full length 1/4 wave. The only problem it causes is it becomes really wide at the top.
prcguy
prcguy
Ok, the whole diversity / picket fencing thing.
It appears to me to be a stealthy, less ham-sexy replacement for the multiple-element Nil-jon antennas, whose claim to faim is diversity.
Inside - who knows? Instead of using physical diversity / angling of larger elements, perhaps inside multiple elements are phased electrically to accomplish much the same. Is the goal to emulate a hemisphere of the isotropic standard in directional patterns?
I suppose we need to actually test one to see.
It appears to me to be a stealthy, less ham-sexy replacement for the multiple-element Nil-jon antennas, whose claim to faim is diversity.
Inside - who knows? Instead of using physical diversity / angling of larger elements, perhaps inside multiple elements are phased electrically to accomplish much the same. Is the goal to emulate a hemisphere of the isotropic standard in directional patterns?
I suppose we need to actually test one to see.
I have been using this antenna for quite sometime with excellent results in VHF and 700/800. Haven't had a chance to use it on UHF due to a lack of a mobile, but VHF is a good performer rood mounted with an NMO on the roof of an SUV.
https://www.tessco.com/products/displayProductInfo.do?sku=368700&eventGroup=4&eventPage=1
https://www.tessco.com/products/displayProductInfo.do?sku=368700&eventGroup=4&eventPage=1
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