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.
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.