Don Markley /
06.01.2006 12:00 PM
Technology seminar: RF

The emphasis was not on high power this year — at least not to the extent seen in the past. High power was still there with high-efficiency tube transmitters for both analog and digital systems. But the big interest seemed to be more in the low- and medium-power levels. In particular, several manufacturers were offering products for use in single-frequency networks.

Exciters

Axcera emphasized its new digital TV exciter, the Axciter. With its companion upconverter unit, the Axciter provides an output signal on any television channel through selection on the front panel. The exciter is available with a complete digital signal analysis system.

The system software can be upgraded easily. The upgrade is simply loaded on a USB Flash drive, which is then plugged into one of the USB interfaces on the exciter. The new unit can also be used in the slave mode for single channel distributed transmission uses.

Transmitters

Ai has been successful with its water-cooled tubes. Many of those units have been installed and are performing well, offering improved efficiency.

Larcan and Rohde & Schwarz both showed lower-power transmitters for either standalone DTV facilities or single-channel network use. The Larcan transmitters can be configured for either analog or digital use by the selection of the exciter. The units range from 10W to 200W.

Of course, the low power makes them good candidates for mobile video and for television translators. The construction of the company's FM translator is similar, with full frequency agility for both the receiver and transmitter.

The Rohde & Schwarz transmitters at low power also lend themselves to LPTV use or to the construction of single-channel networks. The company also showed its heavy involvement in the delivery of content to mobile users with the QUALCOMM technology. The company is also working with Samsung and demonstrated A-VSB technology.

Harris has also been working extensively with QUALCOMM, using MediaFLO for the delivery of multimedia content to mobile handsets. Toward that end, Harris showed its Atlas and Ranger Mobile TV transmitters, which use the Apex television exciter. Harris and Rohde & Schwarz showed complete lines of solid-state DTV transmitters at various medium-power levels.

ENG

A big area this year was the development of microwave systems for either STL or intercity use. MRC displayed continued development of HD and SD systems using IP interface types. Those systems support real-time streaming or video-file transfer in non-real-time formats. The company showed new products for mobile systems. Nucomm also displayed new ENG technology, including systems for the relocation problems in the 2GHz band.

Every now and then something from the radio world seems to find use in television. Broadcast Electronics created the Big Pipe STL for HD radio, but it also provides a cost-effective link for television. The system has more than enough bandwidth and can use all the popular formats. It operates in the 5.3GHz band without a license or in the 5.8GHz band for longer paths.

Antennas

Antennas were interesting this year. RFS' antennas are now manufactured in Australia, as are its filter products. At the show, the company emphasized its filters and manifold combiner systems.

Dielectric had several new antenna products to sell. Perhaps the most unique was a small broadband batwing for UHF frequencies. The unit is omnidirectional and is different because the batwing elements are cut out of a sheet of material. The entire unit is within a radome and can be mounted on a motorcycle or car as the radiator for an ENG system. The antenna also would serve well as a lower-power auxiliary, an LPTV antenna, in single-frequency networks or as a television translator.

Dielectric also displayed a UHF array with 30-channel bandwidth. The antenna is available in medium- or high-power versions. It is a slot-type antenna constructed on panels that can be removed for repairs if necessary. The slots are radome covered. The antenna is available in eight-through 30-bay configurations for gain and can be used for directional antenna purposes.

The previous Dielectric panel array has been modified by adding stainless steel backscreens and radiating elements. The TUA-M is a mid-power antenna primarily designed for multiplexed operation for digital and/or analog stations. The multiple panel approach allows for custom beam tilt and null fill applications. The individual panels are radome covered, or the entire antenna can be placed in a cylindrical radome for wind loading purposes. In all, it is a nice modification of a proven existing product.

Electronics Research showed a new VHF batwing antenna. The antenna was different because it was not constructed on a pole. Instead, the antenna is supported by a square tower section. All the necessary cables are run inside of the tower section instead of being fastened outside of a monopole. This provides better protection from ice, lightning and tower climbers. The routing of the lines inside the tower also allows better grounding with reduced damage from arcing.

New markets

A big issue in the RF arena this year was the obvious development of new markets for traditionally broadcast TV manufacturers. The transmitter companies were looking into lower-power operations for use in new technologies to provide data and video directly to handheld devices. Several were working with QUALCOMM in its new distribution system.

It is apparent that the big transmitter sales and antenna installation boom will soon take a major nose dive. Essentially, all TV stations will have installed new antennas and transmitter systems for digital television. With the exception of further maximization or new stations, the traditional TV market will be shrinking until the normal replacement cycle starts well on down the road.

On the other hand, the 700MHz areas and the 1.7GHz band are both buzzing with new applications and new services. The 700GHz areas are simply the high end of the old UHF broadcast band where a lot of experience exists in transmitters and antennas.

The new lower-power transmitters appeal directly to that market — as are many of the newer antenna systems. There is the growth of combiners to join several transmitters into a single antenna in either of those bands. The combiner companies see a large future demand for that product as do the antenna and transmitter manufacturers.

Just the tip of those developments was visible at this year's show, but it is certain that next year will reveal even more.




Don Markley is president of D.L. Markley and Associates.



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