Copyright ©1998, RF Specialties Group.
When it comes to
the sidemount versus wrap-around panel antenna question, there are advantages
and disadvantages to each. Whereas the sidemount antenna's performance can be
hugely affected by the tower structure, the panel generally is not affected (a
typical broadband panel antenna is omnidirectional +/- 2dB). The panel antenna
can achieve better null fill and beam tilt than most sidemount antennas and is
the only option for the high power requirements of more than a few stations. But,
a panel antenna system has greater windload to overcome, and generally requires
a sturdier tower with a wider tower face. Panels come in a variety of models and
capabilities, both for three-sided and four-sided towers, including a Jampro modular
model that will create just about any pattern.
Conversely, broadband sidemount antennas make excellent master antennas for the branched system, as they're easy on the budget and, these days, can accommodate three or four stations across 10 MHz. Electronics Research's SHPX sidemount antenna has a widened frequency response for the three or more station combiner, as does Dielectric's DCR-M8. You'll find similar upgrades in all the sidemount antennas offered by the major manufacturers.
Still not certain? Consider price. "If you take a look at your standard, everyday ring antenna and compare it to the panel antenna, there's almost a five times dollar value. A two or three bay panel antenna will cost five times the equivalent ring sidemount," said Bob Surette, manager of RF Engineering with Shively Labs.
RF Specialties offers antennas and accessories manufactured by Andrew, Antenna Concepts, Cablewave, Dielectric (including the new Dielectric TDM VHF TV antenna, which now covers the FM frequency band), ERI, Jampro, Mark Products, Micro Communications, Scala, Shively, SWR, and others.