dTR/H&D Joint Venture Projects


A partial list of dTR/H&D Joint Venture Projects and References

  • Implementation of New Antenna System, WWJ Detroit, MI
    Pioneer broadcast station WWJ received authority to change its transmitter location and increase power as a result of the construction of a new television tower at its previous site. JV partner firm dLR was engaged to review and analyze the antenna design (performed by others), to design the feed system, and to assist in its construction and commissioning.

    This 50 kW two-pattern directional array, located southwest of Detroit, uses antenna towers of different heights. Because of the extreme pressure for completion of the project in time to accommodate the FCC mandated DTV tower construction, no modifications of the antenna design could be made. Careful moment-method and whole-system circuit analysis modeling was necessary to ensure that the resulting feed system design would provide proper impedance matching and good bandwidth because of the characteristics of the antenna design.

    Ron Rackley provided this analysis, designed the feed system, and reviewed all of the equipment construction before installation. He then provided supervision of the construction effort, as well as the adjustment of the array.

    Client reference:
    Glynn Walden
    410.872.1526
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  • Indefinite Delivery Agreement for Medium Wave Antenna System and Propagation Analysis, Kintronic Laboratories, Inc.
    Kintronic Laboratories, Inc. (KTL) is the leading specialized manufacturer of antenna equipment and system components for medium wave antenna systems in the world. The Joint Venture firms have used Kintronic as a supplier on behalf of their medium wave antenna system clients for many years, and JV engineer Ron Rackley is a former senior engineer for KTL. Because of the JV firms' expertise in complex medium wave antenna and propagation matters, KTL frequently calls on the JV to provide specialized support services as a subcontractor in these areas. These projects are almost all in overseas locations, and KTL relies on the JV because of its proven past performance in government and private sector projects for cost, quality, compliance with standards, and schedules. These projects include all of the aspects of
    • Maintenance
    • Repair
    • Alteration
    • Construction

    Client reference:
    Tom King
    423.878.3141
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  • Mexico City, Mexico 1110/1560 Diplexing and 1150/1320 Diplexing, Kintronic Laboratories, Inc.
    Mexico City is densely populated, and antenna site space is at a premium. KTL has undertaken two complex diplexing projects, both of which were designed and implemented by JV engineer Ron Rackley working with KTL. The projects both involved new transmitters and antenna system equipment, as well as physical changes in the antenna configurations. Both changeovers were accomplished while maintaining a normal broadcast schedule. Whole-system modeling made it possible to accomplish the necessary filtering with complementary compensation of bandwidth effects. Moment method and nodal network computer modeling were employed.
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  • Puttulam, Sri Lanka and Bonaire, Netherlands Antilles Antenna Design and Propagation Analysis, Kintronic Laboratories, Inc.
    TWR operates high power (400 kW and 500 kW) medium wave transmitting sites at these locations. TWR and KTL engaged the JV to assist in antenna design and extensive propagation analysis to allow replacement of the existing transmitting systems. This alteration to operate with more efficient antennas and with lower transmitter power will reduce operating costs. TWR now has these facilities under construction, and JV engineers will perform the construction support services to implement and commission the antennas. JV engineer Ron Rackley performed the antenna design portion of the project, and Ben Dawson performed the propagation analysis.
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  • São Tomé, Antenna Inspection, Kintronic Laboratories, Inc.
    The Joint Venture and KTL performed the original design and installation of the medium wave antenna at the IBB São Tomé relay station. After it was modified by others to 600 kW operation, the high-speed monitoring sensor of the transmitter employed at this site would interrupt the carrier for a few milliseconds on a random basis, sometimes several times during a daily operating cycle. JV engineer Ben Dawson inspected the system and after a complete investigation and engineering analysis determined that the antenna system did not appear to be the source of the problem, which would not have occurred except for the very high speed protection circuitry in the transmitter, designed to protect its critical solid state driver stage.
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  • Indefinite Delivery, A/E Services for VOA (IBB) Medium-Wave Antenna Systems
    The dTR/H&D Joint Venture was originally formed to provide the expertise of both of the member firms for VOA antenna system projects, in 1987. Since the original world-wide medium wave antenna system inspection project in that year, the JV has performed over twenty projects for VOA/IBB. Since 1994 these have primarily been performed as individual task orders under this contract and a similar contract for Radio Marti. These projects include the same scope of work areas as the current RFQ: Medium Wave Engineering Services; Design and Adjustment of High Power (up to 1000 kW) MW Antenna Systems; Calculation of Electromagnetic Radiation Hazard Levels/Zones; and Design, Maintenance, Repair, Alteration, Construction, Installation, and Tuning of MW RF Broadcast Systems.

    Client reference:
    Mark Prahl (Project Manager)
    202.205.9096
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  • Non-ionizing Electromagnetic Radiation Projects, Delano Maximum Permissible Exposure, Evaluation and RF Safety Training
    IBB engaged the Joint Venture to provide analysis and measurement of non-ionizing radiation levels at the Delano HF transmitting facility, and a subsequent report. The preliminary analysis phase required calculations of anticipated electric and magnetic field levels near a representative selection of the antennas in use at this site, which were preformed by JV engineer Matt Folkert. The Delano site uses rhombic and curtain antennas, and the extensive calculations were presented as multiple color maps for each antenna for clarity.

    After this analysis was completed, JV engineers Jim Hatfield and Steve Lockwood traveled to the site, and made a complete set of measurements to confirm the calculations. While at Delano, Hatfield provided the on-site IBB employees with an RF safety training session--conducted twice so that all personnel could attend. This safety training course was later videotaped for use by IBB systemwide.

    In addition to a complete report on the analysis and measurement program, the final report for this project included an updated model safety plan, including specific additions for the circumstances of high power HF sites.

    Client reference:
    Mark Prahl (Project Manager)
    202.205.9096
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  • Indefinite Delivery/Indefinite Quantity Contract for Broadcast Antenna Engineering B, Harris Corporation
    Harris Corporation, one of the world's largest manufacturers of broadcast transmission equipment, became a significant force in the high power medium wave market with the success of the "DX" series solid state digital transmitters. Because transmitters at power levels of 100 kW and above are sometimes "packaged" with new antenna systems, and because the true power output and high modulation capabilities of replacement "DX" transmitters often place new electrical stresses on existing antenna systems, Harris engaged the dTR/H&D Joint Venture as on-call engineering consultants on high power medium wave and long wave antenna systems matters. These projects are all longwave or MW design activities at high power levels, accomplished in a timely manner, and are all at overseas locations.

    The projects performed for Harris include a full range of medium wave engineering services including
    • Investigation of problems.
    • Performance of engineering analysis.
    • Recommendation of solutions.
    • Preparation of technical specifications.
    • Construction support services.

    Additional Projects Performed by the Joint Venture for Harris
    • Directive Long Wave Antenna Design for Tender in Poland
    • Insulator Voltage Calculations for 100 kW Medium Wave Antenna in Egypt
    • Propagation Calculations for 100 kW MW Antenna, Hafir al Batin, Saudi Arabia
    • ELF Antenna Measurement Procedures and Testing, Five Canadian Navy Sites in Canada
    • Antenna Coupling Measurements Between Two 600 kW BBC Medium Wave Antennas, Ladies Mile, Cyprus
    • Antenna Insulator Voltage and Power Handling Studies for Power Increase of Medium Wave Antenna from 200 kW to 400 kW, Ramallah, Palestine


    Client references:
    John Delay, 217.221.7103
    Don Spragg, 217.221.7266
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  • Antenna Diplexing Design and Implementation, Harris Corporation, Dong Hoi, Vietnam
    The JV investigated the existing 200 kW 639 kHz directional antenna array of Radio the Voice of Vietnam at Dong Hoi. We inspected the antenna and feed system and performed an engineering analysis of its suitability for a second, diplexed 200 kW operation on 729 kHz. We compared alternative feed systems layouts, and recommended an innovative unique single feed system solution for use at both frequencies, using the existing open wire transmission line. We designed a single set of filters and matching networks at the input to the main antenna feed line, together with power division and antenna coupling networks that provide acceptable impedances and voltage stresses at both frequencies. Our work included preparation of construction drawings, cost estimates, schedules, technical specifications, and as-built drawings. JV engineers Ron Rackley and Ben Dawson performed the on-site construction support services and tune-up that allowed normal full power operation on both frequencies 72 hours after the commencement of installation. The system has operated flawlessly for over four years since commissioning.
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  • Conversion and New Antenna Design, Harris Corporation, Iceland
    The JV designed the changes necessary to modify the existing Gufuskular top-loaded 1800 foot Loran antenna tower for 300 kW broadcasting use by the Iceland National Broadcast Service, on 180 kHz, in the European longwave broadcast band. In addition, we provided design of a new 100 kW antenna for use on 207 kHz at Eidar. We obtained drawings and engineering information on the Loran tower from Coast Guard sources. After inspection and a complete engineering analysis of the antenna, including comparison of alternatives, a recommended solution was undertaken by Harris. Included in the work product was a statement of work and complete technical specifications. The new installation at Eidar was the result of an engineering analysis of the coverage requirements and a set of cost estimates for alternative solutions. After acceptance by the Icelandic authorities, the aviation authority reversed its acceptance of the original antenna tower height, and a second set of technical specifications was prepared for the reduced height operation.
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  • Design and Implementation of 2000 kW Directional Array, Harris Corporation, Al Arish, Qatar
    The Qatar government broadcasting service requested tenders for replacement of the existing Al Arish facility with a new 2000 kW transmitter and a replacement for the existing antenna system. The existing antenna was a six tower "sideways Yagi" that had poor bandwidth, would not handle the full power of even the derated original transmitter system, and which had physically deteriorated in the coastal Arabian (Persian) Gulf environment. JV engineers Ben Dawson and Ron Rackley proposed a new 4-element antenna, with split power fed to active elements and carefully controlled pattern shape to meet both skywave and groundwave coverage objectives. Harris has completed construction of the antenna, and commissioning awaits completion of the transmitter installation. The construction support activities performed by the JV include an analysis of the effect of maintaining one element of the old antenna as a standby, as well as an analysis of the influence of a new microwave support antenna near the transmitter building.
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  • Antenna Analyses and Designs, Harris Corporation, Milano and Squinzano, Italy
    Replacement of transmitters by Italian State Radio (RAI) with new higher power "DX" units resulted in a requirement for a complete investigation of insulator voltages on the existing antenna system. JV engineers performed this analysis and compared alternative methods of reducing voltage stresses in the Milan antenna systems. In addition, detuning measures were designed to allow alternative standby modes of operation at the multiple transmitter Milan site. The system has performed flawlessly subsequent to this alteration. At Squinzano, a complete feed system was designed by the JV to allow dual frequency operation of an existing antenna system. The system has very closely spaced towers, and considerations of bandwidth, voltage stresses, and stability were important in the preparation of the design and technical specifications. This system is currently under construction, and JV engineers will perform the site construction support services and commissioning later this year.
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  • Antenna Design and Site Layout Analysis for Two Megawatt and Three 500 kW Medium Wave Antennas on Common Site, Harris Corporation, Can Tho, Vietnam
    Harris supplied a total of four transmitters to this site, and the JV was commissioned to design the antenna systems and layout to allow proper operation of all four transmitters without interaction or intermodulation. The design provided to Harris by the JV was used for construction of this site, which is now in operation.
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  • Antenna System Refurbishment Engineering Services, WDFN Detroit, MI
    WDFN operates with a nine-tower directional antenna system. Its protection requirements and high power operation, together with the number of towers, make it among the two or three most complex and critical medium wave directional antenna systems in the world. It had been out of proper adjustment for many years prior to its acquisition by Chancellor Broadcasting, and former owners reportedly had spent over a million dollars in engineering fees in fruitless attempts to "make it legal" in conformance with its FCC license requirements. JV engineer Ben Dawson inspected the facility at the time it was acquired by Chancellor, and recommended that mechanical reconditioning and a new analysis of the allocation circumstances be undertaken. When Chancellor and Evergreen Broadcasting merged shortly thereafter, JV engineer Ron Rackley made similar recommendations to Evergreen. The Evergreen-Chancellor merger companies engaged the Joint Venture to resolve the problems and return the antenna system to proper compliance with FCC standards. Jim Hatfield inspected the antenna system and conducted a complete engineering analysis of the antenna system using modern moment-method and circuit analysis techniques, and determined a set of design-center operating values. Dawson and Matt Folkert conducted a complete allocation analysis to determine the limits on radiation from the antenna in various directions. After mechanical refurbishment recommendations were complete, Rackley, Dawson, and Folkert, together with field technicians, conducted a measurement and adjustment program over a period of five weeks. The adjustment and measurement program resulted in complete conformance with FCC allocation and operation requirements. The antenna system has subsequently been stable and continues to meet all standards and compliance requirements. The project was performed under budget and on schedule.

    Chancellor also owns another high power nine-tower directional array, KFAN, Minneapolis. At the time of purchase it was also out of adjustment and extensive efforts by previous consultants to meet the compliance requirements had not been successful. JV engineer Jim Hatfield investigated the problem, prepared an analysis and recommended solution, and supervised measurements by the owner's engineering staff which resulted in subsequent compliance with FCC allocation and operation requirements.

    Client references:
    Mike Dault, 313.259.4323
    Jeff Littlejohn, 513.721.1050
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  • Facility Study and Improvement Recommendations, Liberty 963, London, U.K.
    Commercial radio broadcast licensing in the United Kingdom is carried out by a quasi-government body, The Radio Authority, subject to minor technical overview by the Home Office Telecommunications Agency. The Radio Authority has authorized a large number of local radio broadcasting stations, which are limited in power and service area. In metropolitan London the allowed transmission facilities are inadequate to provide service to much of the urbanized area, in part because of the unavailability of efficient antenna systems in this densely populated metropolis.

    JV partner firm Hatfield & Dawson was engaged by Liberty 963 to provide investigation, planning, design, and a recommended solution to this woefully inadequate service situation. Ben Dawson met with officials of the Radio Authority, and determined that there were no really consistent allocation standards employed domestically by the Authority. Investigation of the international allocation situation disclosed that Liberty 963 could operate with substantially greater power nighttime on its original frequency, as well as high power daytime on the adjacent channel 972 kHz.

    A report showing this analysis was presented to the Radio Authority. They declined to allow operation with higher power or the use of different frequencies for daytime and nighttime operation. They would not authorize higher power due to perceived restrictions on service outside the authorized London area.

    After additional discussions, an alternative solution was recommended by H&D. The allocation analysis disclosed that full-time operation on 972 kHz was completely acceptable internationally and appeared to be acceptable domestically. Because of the power limitations imposed by the RA on either frequency, preventing coverage of all of London with a single transmitter site, H&D recommended operation on 963 kHz from an east London site, with simultaneous operation on 972 kHz at a west London site near Heathrow. Modulation bandwidth limitation was recommended to prevent adjacent channel interference. The Radio Authority accepted this solution and allowed Liberty to conduct tests after H&D prepared complete technical specifications for the two-frequency operation, including the engineering analysis of both sites.

    The tests were completely successful, and further regular operation was authorized by the Radio Authority. The two-frequency operation has now been in effect for over a year with very satisfactory essentially seamless coverage of metropolitan London.

    Client references:
    John Ogden, 0171.225.6755
    Neal Rodford, 0171.225.6808
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  • KXTA Los Angeles, CA Diplexing with KTNQ at the Towers Industrial Park Medium Wave Transmitter Site
    In 1991 Joint Venture partner firm duTreil, Lundin and Rackley completed the commissioning of the antenna system changes to allow construction of the Towers Industrial park warehouse/industrial building on the 40+ acre site of the fifth kilowatt five-tower KTNQ directional antenna system, which was originally designed by dLR senior partner Bob duTreil in the mid-1970s.

    In 1997, dLR was engaged by Jacor Communications to refit the five-tower array to add a second 50 kilowatt medium wave operation to this antenna system by KXTA-AM. This project, like the original one, had very strict scheduling requirements, and was mechanically very complex. Ron Rackley and Matt Folkert of dLR performed the necessary engineering analysis to allow KXTA to increase power to 50 kW, specified the feed system design, prepared the specifications and drawings of equipment configurations, provided construction supervision, and working with Jacor staff engineers commissioned the operation on a very tight time schedule in order for Jacor to meet a contract commitment for Dodgers baseball broadcasts.

    After completion of construction, JV partner firm Hatfield & Dawson was engaged to conduct a complete survey of EMR/RadHaz circumstances at the site. This study, performed by JV engineer Jim Hatfield, showed that the upgraded screening and shielding design provided adequate attenuation to reduce radiation limits below the applicable standards.

    Client references:
    Al Kenyon, 606.655.6540
    Bill Suffa, 606.655.6530
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