The FM Channel combiner shown above is combining WMIA-FM, WMGE (FM), WHYI-FM, WMIB (FM), WAXY-FM, and WBGG-FM. The combined signals are fed to an ERI Model SHPXA-12BC-HW-SP AXIOM Master FM Antenna. The combiner and Master FM antenna are located at the American Tower Pembroke 2 Site in Hollywood, Florida.
The FM antenna pictured is a shared aperture ERI ROTOTILLER. The array is two antennas, one for the analog signal and one for KNOW-FM’s HD Radio digital signal. The analog antenna is an ERI Model SHP-8AC, eight bay circularly polarized FM antenna and the digital array is an LP-7C. Both antennas are equipped with optional radomes for protection for heavy snow and ice. To enhance isolation between the antennas they are cross polarized, the analog antenna is right hand circular polarization and the HD antenna is left hand CP. Each antenna is fed by it own transmission line. The benefit of using antenna space combining for simulcasting analog and digital IBOC signals is that this approach eliminates combining losses that are present in systems that use high level combining. This approach also uses separate analog and digital FM transmitters which are more efficient than common amplification transmitter systems.
The photo above was taken in late October 2013 of KPLZ-FM, STAR 101.5, at their transmitter site on Cougar Mountain. The antenna is a specially constructed 0.8 lambda spaced 8 bay ERI SHPX Series ROTOTILLER FM antenna. The special branch feed system is constructed entirely of rigid coaxial transmission line which makes the system far more rugged and long lived than the fractional bay to bay spaced designs offered by other manufacturers.
In addition to providing the FM antenna ERI also supplied a run of 3-1/8-inch ERI MACXLine, structural reinforcement material, and performed the installation of the antenna, transmission line, and encapsulated and painted the tower.
At the end of October the installation of the new KUNS-TV RF Channel 50 (Virtual Channel 51) UHF television antenna was completed on the KOMO 4 TV tower on Queen Anne Hill in Seattle. The new antenna pictured above is side mounted below the KOMO antenna which is an ERI top mounted TRASAR antenna mounted at the tower top. Both antennas are elliptically polarized and feature pressurized radome enclosures. KOMO 4 TV is the ABC affiliate serving Seattle and KUNS-TV is an affiliate of the UNIVISION television network.
ERI was hired by Clear Channel to bring down at 490-foot guyed tower outside of Mobile, Alabama, over the weekend. I was fortunate enough to be able to go record that and provide photos of the event as a part of this posting. The tower was a Rohn Model 80 pipe leg design more than 40 years old. It is not surprising, given its Gulf Coast location, that over those years it had begun to rust inside the pipe legs. It was determined that tower was not safe to leave up and could not be de-stacked with a gin pole. ERI engineered a plan for dropping the tower within the confines of the tower site. Thanks to Clear Channel’s excellent relations with the community and competence at managing large projects, coupled with ERI’s skills and capabilities, the controlled drop of the structure and clean up was completed in less than one week.
A slide show can be found here: http://tinyurl.com/8j498fm
A video of the of the tower falling can be found here: http://sdrv.ms/13sif6d
Bill Harland
WTIC-FM uses a dual input ERI model 1083-2CP as its main FM antenna. This antenna was built and installed in 2006 and features dual inputs for analig and digital HD FM signals. The link is to Mike Fitzpatrick’s site NECRAT.us.
Bill Harland
Tim Portzline has had posted for some time at his site, Harrisburg Radio and TV, some photos of the installation of WHP-TV’s TRASAR digital television antenna in December of 2008, http://www.harrisburgradiotv.com/WHP-TV/new_whptv_antenna.htm. This antenna was unusual as and a bit more difficult to design than is typical, as it had a very unusual horizontal plane pattern to protect a nearby Channel 21 (co-channel) facilities in Maryland and New York (Long Island). More of a tri-lobe than a cardioid pattern.
Bill Harland 