Gray Hoverman

The Gray-Hoverman Antenna For UHF Television ReceptionMarch 11, 2008 Updated March 22, 2008 (corrected SBGH performance plots) http://www.digitalhome.ca/ota/superantenna/design.htm

This project is dedicated to Doyt R. Hoverman (b.1913), the man who created and did the early work on the Hoverman antenna at a time when antenna modeling programs did not exist. His work would have been entirely created and improved by field testing, trial and error, and with a great amount of calculation without the benefit of electronic devices. Without his efforts, our work would not have been. Doyt Hoverman passed away in December, 1989 at Van Wert, Ohio, USA.

First, A Bit About The Original Hoverman Antenna

Doyt R. Hoverman's original design for a television antenna was granted US patents #2918672 on 22 Dec 1959 and #3148371 on 8 Sept 1964, which expired in 1979 and 1984 respectively. To view them, click on this link and then simply enter the patent number mentioned above to retrieve each.

In his patent applications, Hoverman describes two designs with 4 rod reflectors, full wavelength and co-linear half-wavelength reflectors, with the second design using the following specifications:

Driven array = 56" dual segments with 8 subsections of 7" (same as the first design) Reflector spacing = 3.5"

Full Wavelength Reflectors:

o Top and bottom = 29"

o The two middle = 24"

Half Wavelength Co-Linear Reflectors

o Top and bottom = 14"

o The two middle = 10"

The above dimensions are for reception of UHF channels ranging from 14 to 35, as claimed in the patent. He gives design equations for shifting the range, and suggests 35-58 and 58-83, although the range 58-83 is not applicable now as UHF TV channels in North America only go to 69, and after 2009 will only go to 51.

The original Hoverman antenna design did not have a reflector and used a driven array of 56" segments with eight zig-zag 7" sub-elements. The original patent # 2918672 claimed UHF and VHF reception. The modeling results did not find any positive net gain for VHF Low channels 2-6 nor for VHF High channels 7-13.

There is very little information available anywhere on the Hoverman antenna. The only reference to any commercially manufactured Hoverman antennas seems to be in the article (PDF) The Hoverman, VUD Sept 1982, which mentioned a 4 bay Hoverman made by AntennaCraft named the model G-1483 and which was also made for Radio Shack as the model 15-1627, seen in this photo courtesy of tvlurker:

Some of these commercially manufactured Hoverman variants used 7 pairs of collinear rod reflectors. Judging from the AntennaCraft and Radio Shack websites and many Internet searches those Hoverman models do not seem to be currently in manufacture, although it seems that old stock of the AntennaCraft Super-G 1483 is or was available from SummitSource.com.

Recent Research On The Hoverman

Canadian antenna buff Autofils, speculating in an online discussion of Build It Yourself Antennas on the Digital Home web site in early 2008 on the possibility of experimenting with the old Hoverman Antenna design, sought out old sparks, another Canadian antenna enthusiast, who used 4NEC2 computer antenna modelling software to model the original Hoverman design. His research showed that the Hoverman had poor SWR but certainly exhibited strong gain either as a bi-directional antenna or, if one were to put a reflector screen on it, as a unidirectional antenna.

With assistance, advice, and encouragement from fellow antenna enthusiasts, an ad hoc research and development team came together. Using NEC II, 4NEC2, and EZNEC computerized antenna modelling software, the original Hoverman design was reconfigured in many ways over the weeks to discover whether improvements upon it could be achieved. The R&D team included Canadians GerryB, myself as moderator (stampeder), kro, 99gecko and DjiPi, joined at the same time by Americans DogT, oneolddude as well as Keo, amongst others. Thanks to Ken Nist (kq6qv) for his antenna modeling and graphing tools and assistance.

Introducing the New Gray-Hoverman AntennaWith ongoing correspondence, design improvement, and real world testing, Autofils' resulting design has achieved an extraordinary leap in UHF Television Antenna reception performance that rivals and beats most or all of today's commercially available UHF Television antennas.

"Boy, this antenna is hot. I finally got it pointed right. After I did a search for channels, I got 23 digital channels, and this is from about 30-40 miles, over mountains. I now get all 4 digital network channels from DC, 48, 36, 39, 34 (ABC, NBC, FOX, and whatever the other one is, PBS, MHZ, and a 6 channel digi mostly religious station. I was not really interested in the analog channels, but they were the only ones I could measure with the analyzer. This antenna is a vast, and I mean REALLY VAST improvement over anything I have used." -- DogT

Today we are delighted to announce the public availability of the Gray-Hoverman UHF Television Antenna designs, schematics, and diagrams, Copyright ©2008 and licensed under the GPLv3.

There are two Gray-Hoverman configurations: Single Bay Gray-Hoverman (SBGH) for nearby to fringe reception range (approx. > 0 to 100

km or > 0 to 60 mi)

Two Variants of the SBGH:

o with 6 Pair Collinear rod reflectors o with 30 x 40 Split-Screen Reflector

Double Bay Gray-Hoverman (DBGH) for fringe to deepest fringe reception range (approx. 30 to > 160 km or 20 to > 100 mi)

Two Variants of the DBGH:

o with 11 Pair Collinear rod reflectors o with 30 x 75 Full-Screen Reflector

Gray-Hoverman Antenna Performance

Seeing is believing, so let's examine some of the test result diagrams of Gray-Hoverman design variants, paired with similar class commercial-brand competitors for comparison. We've chosen as benchmarks the highly regarded Channel Master 4221 4-Bay Reflector UHF Antenna and its bigger sibling, the 4228 8-Bay Reflector UHF Antenna, which is generally considered to be the best commercially made consumer antenna available for reception in North America.

As has been mentioned above, the North American spectrum of UHF Television channels will span 14 through 51 in the coming years. Thus, performance on channels above 51 was not deemed to be an important focus of our research and design resources.

For analysis by any NEC modeling software, the voltage source that drives the antenna model under test must be located at exactly the center of the antenna's feed point.

SBGH Modelling Error CorrectedIt has been discovered that for the SBGH ez modeling files depicted below, the voltage source had a small offset. The major effect of this modeling error was to produce a single minor asymmetrical lobe in the SBGH polar plots at frequencies above 600 Mhz up to the upper design frequency of 700Mhz., with the max minor lobe occurring at 670Mhz.

New SBGH plots with the corrected Vsource are now provided here. You will note that there are now two symmetrical minor lobes, as is expected when the antenna feed-point is driven exactly at the center. There is very slight effect on net gain. The correct voltage source shows slightly more gain at the lower frequencies. There is almost no change in the Swr.

The DBGH files had the correct location of the voltage source from the beginning and do not have any known errors.

Single Bay Gray-Hoverman (SBGH) vs. Channel Master 4221 4-Bay Reflector UHF Antenna:

DBGH vs. CM4228:

Single Bay Gray-Hoverman (SBGH) Corrected Graphics:

The Gray-Hoverman Antenna Designs, Schematics, And Diagrams

Single Bay Gray-Hoverman Diagram Original Manuscript, Copyright ©2008:

Double Bay Gray-Hoverman Diagram Original Manuscript, Copyright ©2008:

Gray-Hoverman Construction Examples

Photo of PVC-fabricated Double Bay Gray-Hoverman Designed and Built by DogT: