Wi-Fi

Venti Antenna: A big signal from a small package

Antenna systems have been in the news lately, thanks to the iPhone's antenna issues. Apparently, compromises were made. A new antenna design may have prevented that.
Ask any amateur radio operator (including me) if antennas are important. Nine times out of ten, the answer will be: Absolutely. That priority should apply to all RF devices. But, other considerations come into play. I don't think too many of us would like wearing a Bluetooth head set if it had a 10-centimeter-long antenna sticking out of it.

The Venti Antenna

So, compromise comes into play. And, in many cases, the antenna system is the component that suffers. That's why I am always on the lookout for new antenna technology. Recently, I read about a new system called the Venti Antenna. The company was making some amazing claims and I had to check them out.

I got in touch with Tony Eichenlaub and Hank Adamany, Managing Partners of the Venti Group, and asked them the following questions:

TechRepublic: Could you tell us about the company and its focus? Venti Group: The Venti Group develops, acquires, and sells Intellectual Property pertaining to wireless technology. Venti Group, LLC is a privately held company represented and owned by engineers, scientists, and entrepreneurs. TechRepublic: There isn't much technical detail about the Venti Antenna system on the website other than the illustrations. The first slide depicts a Venti Antenna with two RF signals/data streams. Is that similar to MiMo? If not what does it designate?

Venti Group: The slide does represent a MiMo transmission; the Venti antenna can be combined with a vertical dipole to provide transmission/reception of both vertically and horizontally polarized radiation. Such dual-polarized antennas can increase the robustness of the system through polarization diversity (i.e., it is unlikely that both polarizations are in a fading dip simultaneously). It also means different data can be transmitted on the two polarizations, increasing the data rate. TechRepublic: The next slide talks about how the Venti Antenna system addresses physical interference, including the human body. Can you elaborate on that, please?

Venti Group: The radiation pattern of the Venti Antenna would be parallel to the handset as opposed to the perpendicular pattern of current antennas. This greatly reduces the radiation directly absorbed by a handset users head. TechRepublic: The figure-eight antenna pattern you compare the Venti Antenna to is typical of a dipole antenna. The Venti Antenna's horizontal pattern resembles that of a vertical antenna with ground planes. Can you describe how that's accomplished?

Venti Group: The comparison picture shows a vertically-polarized dipole antenna pattern and its lack of omni-directionality. One advantage of the Venti Antenna is that it provides a uniform pattern, with only 1-2 dB ripple (deviation from perfect omni-directionality). That reduces dead spots caused by insufficient signal strength and/or interference.

Also, the Venti Antenna does not require a ground plane allowing for freedom of design in wireless devices and even further reduced cost.

TechRepublic: You mentioned the Venti Antenna uses horizontal polarization. Don't most other wireless devices use vertical polarization? If so, is that a problem? Venti Group: Antennas using horizontal polarization are becoming increasingly important in cellular communications and WLANs. Older cellular communications systems used vertically-polarized antennas, such as rod antennas on cars or pull-out antennas on the handsets of the 1990s. These antennas were used because they are easy to manufacture.

In recent years, there has been increased interest in antennas using horizontal polarization. That's because horizontal polarization in newer wireless devices works as well if not better than vertical polarization, due to the emission characteristics of modern handsets and propagation characteristics of indoor and densely built-up areas.

Furthermore, horizontally-polarized antennas can be combined with vertically polarized antennas to form compact multi-antenna systems.

TechRepublic: The next illustration is one that I find amazing. The fact that the Venti Antenna is electrically-comparable to existing antennas and its form factor is less than two centimeters in diameter. Could you explain how that is possible?

Venti Group: Yes, the dimension given is for a 5.85 Ghz Venti Antenna. The Venti Antenna is "compacted" by use of conventional loading or folding techniques such as inductive loading, capacitive loading, folding, dielectric loading, etc. The size reduction can be furthered if efficiency is not a concern, as in such devices as Bluetooth where close proximity is part of the application. TechRepublic: As an amateur radio operator, I realize the importance of VSWR and how difficult it is to obtain a value of 1.3:1. Can you talk about that? Also, the Wi-Fi and wireless frequency spectrum is quite broad. Are you able to maintain that value throughout the entire range?

Venti Group: Yes, the Venti Antenna has an extremely wide frequency bandwidth and is able to maintain its low VSWR.

Independent research paper

The Venti Antenna is in the process of getting patented, so the Venti Group is keeping the neat technical stuff under wraps. They did send me a redacted report written by well-known wireless researcher Dr. Andy Molisch of USC Viterbi School of Engineering. The professor mentioned the following in the paper's conclusion:

  • Measurements provided by the inventing company show an excellent omni-directionality combined with a large bandwidth.
  • The Venti Antenna compared favorably with a large majority of existing designs.
  • The Venti Antenna is considerably less complicated than alternative antennas, therefore will have lower manufacturing costs.
Final thoughts

The omni-directional capabilities, extended bandwidth, low VSWR, and small form factor bode well for the Venti Antenna. It will be interesting to see if and when wireless-device manufacturers start incorporating the Venti Group's antenna technology.

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17 comments
Vulpinemac
Vulpinemac

... they may have difficulty getting the patent since many aspects of this antenna system are so similar to the antennae used on Apple's iPhone4--which is either already patented or has the patent pending. Based on prior art then, the Venti group will probably be rejected.

santeewelding
santeewelding

Arecibo-like alterations to either side of the skull, Venti implanted at the foci?

agilebrainz
agilebrainz

>>This greatly reduces the radiation directly absorbed by a handset users head.

Michael Kassner
Michael Kassner

I suspect, I would get dizzy trying to obtain proper reception.

Hazydave
Hazydave

Cellphones produce nonn-ionizing radiation.. It simply cannot break DNA strands, disrupt DNA replication, or do anything else to cause cancer. With that said, of course you'd prefer most of the phone's energy to not be directed into your body, where some will be blocked. But changing to a directional antenna fails.. In most cases, you don't.Know where the cell is located. As for the iPhone, the main problem is the exposed antenna that's easily shorter to the similarly exposed Wifi antenna. The other problems is that the iPhone doesn't employ conventional diversity antennas, which would solve the problem, much as it does in many modern smart phones. As for the small size of this antenna.. they're showing a 5GHz antenna.. much shorter wavelength than the 1900MHz/850MHz antennas in the US iPhone.

Michael Kassner
Michael Kassner

I think one thing they were looking into is the fact that a better antenna requires less power to obtain an equivalent range spec.

Vulpinemac
Vulpinemac

... an image of the Venti antenna? The simple sketch in the article really doesn't give you a decent view. If the only supposed difference is that it's bigger and mounted vertically in the phone, then it's no better than all the other existing antennae. If it's part of the body of the phone--like the iPhone's steel band--then the patent is already claimed, even if not issued yet. Oh, and having worked on and around aircraft for over 12 years in the military and out, I do know how antennae are supposed to work.

Hazydave
Hazydave

Noticed that too.. Its at least implied in some of the seemingly contradictory details they give. Including the implied "regular" cell antenna, which they have radiating into you, almost entirely. A perfect antenna offers zero gain and a spherical radiation pattern. As you block the antenna, you distortion this sphere. Same with gain.. think of a balloon. If I want a balloon to reach farther along one dimension, another dimension has to shrink. Even a little gain is a potential probelm in a cellphone, because you don't know the orientation of use, in fact, some phones (like the Droid I'm typing this on) are designed to be used in multiple orientations.

Michael Kassner
Michael Kassner

For the various frequency ranges. Although non-ionizing radiation may not affect human tissue as you suggest. A microwave seems to do a number on flesh, so the amount of power needs to be part of the conversation. As for the iPhone, I may disagree. I had a case for mine right from the beginning and it behaved the same way. Several experts have said the problem is related to how the RF signal is polled.

NickNielsen
NickNielsen

We used to heat C-rations and cook hot dogs at the tropo antennas at deployed sites. Just reach around from the back and push your lunch up into the bottom of the beam. Rarely knocked more than 1 dB off the RSL at the other end. :D If your stick was too short, you could warm your hands as well... :0

Michael Kassner
Michael Kassner

I have not seen those on their site. Please trust me, their antenna design is nothing like the one used in the iPhone. As I mentioned, I have seen the report from Dr. Molisch and the Venti Antenna is only 20 mil think and for 801.11a about the size of a postage stamp.

Vulpinemac
Vulpinemac

... who tend to respond to my comments, disparaging my discussion because they feel they have more experience than I. Let's call it a pre-emptive strike against some follow-up poster who thinks they know more. That said, I'm not trying to disparage you or anybody else. Based on what is visible in the sketches (and I did check their website too) the idea is to use a dipole antenna in a V-shape and that's exactly what the iPhone 4 has... up one side and across the top vs one side and the bottom. There really is little difference until you look at the circuitry attached and the extent of pre-loading they use. Since the company doesn't show much detail (they are applying for a patent, after all) you have to go by what's visible, and Apple's antenna has the prior art.

Vulpinemac
Vulpinemac

... doesn't it? Oh, and attack radars on the old F-4 Phantom could light fluorescent tubes as much as 1/4 mile away. Imagine what it would do close up.

Michael Kassner
Michael Kassner

In the article, that aspect is proprietary as of yet. I have seen the antenna designs and it is nothing like the one used for the iPhone. I did not mention anything about your experience. Sorry if you felt that was implied. I do have a bit of my own, being an amateur radio operator for over 45 years.

santeewelding
santeewelding

And, your input, is why I stay glued to this; along with my experience of carrying magnesium flashbulbs in my pockets aboard naval warships long ago -- warned to stay the hell away from radar emanations, which, once, I didn't.

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