Shively Labs FM Antennas and Accessories
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2712 Bandpass Filter


Small footprint, up tp 15kW with blowers

Catch us at:
Alabama Broadcasters' Convention November 27-29
Our Dale Ladner will be presenting a seminar on Care and Feeding of FM Antenna Systems!

A Few Words About IBOC / HD Radio™ Implementation:

As more and more stations implement HD Radio™, broadcast engineers are learning that successful implementation depends on high-quality equipment. Simply being able to “pass an IBOC signal” is not enough. A quality hybrid analog/digital signal requires strict adherence to good antenna and filter design principles. Shortcuts in antenna tuning that were acceptable in the past, such as tuning the radiator high for ice, slug tuning, and unbalanced or asymmetrical radiators are now proving unwise and costly. Poor design not only affects the coverage patterns of both signals, it can also make implementation unnecessarily expensive. Consider, for example, that a simple 3 dB difference in antenna isolation can add $10,000 to the price of an isolator.

Since the early 1990s, broadcaster have been depending on Shively Labs to solve their IBOC implementation problems. During that time, we have pioneered a number of techniques and equipment designs that are industry standards today. These include the square wave mask filter - the first transmission component licensed by iBiquity, precision 10-dB injectors that do not require additional filtering, the low-power FM interdigital filters for IBOC filtering and combining, digital harnesses for back-fitting panel antenna systems without the need of retuning, and interleaved analog-digital antennas. It also includes the development of a number of techniques, including back feeding digital through balanced combiner systems and split feeding combiners to allow analog and digital signals to be swapped in the case of emergencies.

These successes were no accident. Shively Labs antennas and filters are designed from the ground up to produce the performance required for successful HD Radio™ implementations without short cuts and gimmicks. And, as always, we never lose sight of the most fundamental principle of FM transmission – your audience needs to be able to hear you.

Some Useful Links:

FCC Requirements for IBOC Transmission over Separate Antennas:

The FCC allows IBOC implementation using separate antennas provided they meet certain criteria:

  1. The digital transmission must use a licensed auxiliary antenna.
  2. The auxiliary antenna must be located within three seconds latitude and longitude of the main antenna.
  3. The vertical separation of the antennas must be limited such that the auxiliary antenna is within 70 and 100 per cent of the height above average terrain of the main analog antenna.

HDRadio™ is a trademark of iBiquity Corporation.
Last updated: 05/31/11
Webmaster: Al Friend
© copyright 2011 Howell Laboratories, Inc.