AM Broadbanding Services:

Background:

The term bandwidth refers to the proper transmission of the sidebands, frequencies just above and below the carrier frequency.  These sidebands carry the actual audio transmitted, and if not transmitted properly, will seriously deteriorate the listener's percieved audio quality at higher frequenices, and can prevent an IBOC radio from recovering the digital signal at all. For AM transmission systems, wide bandwidth is good; narrow bandwidth is not.  There are two types of bandwidth we must concern ourselves with: VSWR and pattern bandwidth.  VSWR or load bandwidth refers to the quality of the impedance match that the antenna system presents to the transmitter at the sideband frequenices; pattern bandwidth is of concern only with directional antennas and refers to the matching of DA pattern lobes and nulls at both carrier and sideband frequencies.  Broadbanding refers to ensuring that both types of bandwidth concerns are addressed and made as wide as possible.  Although there were some notable early pioneers in the field, most stations were built with little or no attention paid to the antenna system's bandwidth until the 1980s, when solid-state transmitters, which were more susceptible to problems resulting from narrow antennas, and AM stereo, whose performance was seriously degraded with narrowband antenna systems, came along.

Our history with broadbanding:

Michael Patton designed and built his first broadband tuning unit in 1978, a unit that is still in service today (we just got to sweep and tweak it earlier this year, and it's doing fine!).  MP&A has been involved in AM antenna broadbanding research and real-world applications since its founding.  Along the way we have developed measurement techiques and computer analysis software that are second to none.  We have designed and installed many broadband non-directional antenna tuning units, from 250W to 50 KW.  We have also rebuilt many directional antenna phasors and ATUs for greatly improved bandwidth compared to their original designs, and all of our new designs for phasors and/or ATUs take bandwidth into consideration from the first design pass to the last test sweep.

How MP&A addresses bandwidth issues:

All our phasors and ATUs are designed for maximum pattern and VSWR bandwidth and for IBOC compatibility.  As IBOC implementation approaches for more and more AM stations, it will become imperative for stations with narrowband phasors and/or ATUs-and that means most AMs that were built before 1980-to redesign their matching networks to be broadband.  MP&A is ready with the software, test equipment, and expertise to resolve your broadbanding issues.  We can rebuild your existing phasor/ATU system or stand-alone ATU for maximum bandwidth quickly and easily at your site, or we can design and build a maximally-broad phasor and/or ATUs to meet your unique requirements in our facility.

Diplexing:

Nowhere is broadbanding more important than with diplexed systems; by definition a diplexer must restrict the bandwidth afforded each station, to prevent that station from interfering with the others in the diplexed array.  How this deliberate narrow-banding is handled makes all the difference between a diplexed system where each station still has enough bandwidth to operate properly and a narrowband mess.  With a diplexed system, bandwidth considerations must begin at the earliest design stage.  MP&A is experienced in designing, installing and tuning diplexers for maximum bandwidth.  We have learned the tricks about how to "tweak" a diplexed system to keep each station's operating bandwidth at maximum.

Conclusions:

Whether we are building a new diplexed system, a new ND tower or DA array, or rebuilding an existing site for you, we have the expertise, the computational power, and the test gear to ensure that your bandwidth is as good as it can be.  As AM technology requires better and better bandwidth for more and more AM stations, it will become imperative for stations to address and resolve bandwidth issues.  Let us inspect your facility for bandwidth problems and then work with you to eliminate them at reasonable cost.