Reduced-Height MF Broadcast Antennas

Star-H Corporation has developed a new, FCC-Approved low-profile transmitting antenna suitable for use in MF (US AM Band) and other broadcasting applications.  Full-scale testing at 1680 kHz has been completed and the performance of the antenna completely verified.  This unique design was recently awarded US Patent Number 6,580,398..  The antenna is sold and supported worldwide by Kintronic Laboratories, under license from Star-H, as the KinStar™ low-profile AM/MF antenna system.  See Kintronic's web site at http://www.kintronic.com for more information.  Image above shows radiating wires enhanced for visibility.  Actual 3/8" diameter conductors are almost invisible in the actual photograph.  The antenna is approved by the FCC for nondirectional Class B, C, and D AM stations in the US without requirements for proof of performance testing.

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The antenna is predicted by NEC computer modeling to be 93% as efficient as a standard quarterwave monopole antenna, but is less than one-third the height.  Measurements of the experimental test antenna show efficiencies meeting or exceeding this amount.  This is the most efficient reduced-height antenna design available today.  The KinStar antenna also won the Cool Concept award from Radio World magazine at NAB 2003.  The KinStar also has been awarded the R&D 100 Award for 2003 by R&D Magazine as one of the top 100 technological innovations of the past year.

Papers describing the antenna concept, testing, and NEC modeling results were presented in October 2002 and October 2003 at the IEEE Broadcast Technology Conferences in Washington DC, in April 2003 at the NAB Show in Las Vegas by Michael W. Jacobs of Star-H, and in the conference record from the IBC 2003, and are available for download in the Publications section of this site.  Additional technical information will be published and presented as it is analyzed on an ongoing basis.

The antenna shown above operates at 1680 kHz and  is approximately 45 feet high and 105 feet in diameter and is over a full 120 quarterwave radial ground screen.  Details of the feedpoint at the center of the antenna is shown below.  The stainless steel box contains the transmitter and modulator used for testing.

On the air testing from the test site in southwest Virginia under callsign WS2XTR with a transmitter power of 250 watts has concluded and the site dismantled.  The initial series of tests using various impedance matching designs has been completed.  Field measurements were done by independent consultant Don Crane and were analyzed by Ron Rackley of DuTreil, Lundin, and Rackley.  The results of the testing confirm that the antenna performs as expected, with high efficiency and sufficient bandwith for IBOC transmission.  The analysis indicates that the antenna meets FCC requirements for US Class B, C, and D stations. 

Height comparison between the KinStar and the quarterwave monopole it replaces:

 For more information, and to see the independent engineer's report, go to http://www.kintronic.com/site/systems/kinstar.asp

For more information, contact Mike Jacobs of Star-H at mjacobs@star-h.com.