FOLDED UNIPOLE FAQS

Hundreds of AM broadcasters across the US and worldwide have found the installation of a Tunipole™ and Combipole™ Antenna Systems to be a first-class benefit for their stations. The overwhelming choice of these broadcasters is the LBA Technology, Inc. Tunipole™.

Unique in the broadcast industry, the Tunipole™ is a total folded unipole system solution that includes design, engineering, manufacturing, and installation support. LBA Technology and our qualified dealers worldwide will work with you to ensure your Tunipole™ folded unipole antenna delivers outstanding performance.

Product Bulletin: Tunipole™ Folded Unipole Antenna Systems – Product Bulletin (PDF)

Which Tunipole™ Folded Unipole Antenna System should be specified?

LBA Technology research and development has produced four standard models to suit virtually every application. The Tunipole™ folded unipole can be installed on self-supporting towers and towers of unusual design, so be sure to call us to discuss your requirements. We will help you make the right choice for your station.

Standard Models Available

UP-311	3 foldwires, maximum height 600 feet (180m), typical power to 15kW
UP-352	3 foldwires, maximum height 600 feet (180m), typical power to 25kW
UP-611	6 foldwires, maximum height 600 feet (180m), typical power to 25kW
UP-651	6 foldwires, maximum height 600 feet (180m), typical power to 50kW
CUSTOM	A wide range of custom systems can be designed to meet your needs. Contact us for a quotation.

Will the Tunipole™ change my station’s antenna characteristics?

Typical installation of a Tunipole folded unipole antenna system

Installation of a Tunipole™ folded unipole system changes the way in which a steel AM tower is fed radio frequency energy. However, the radiating characteristics of the tower remain essentially unchanged, regardless of where the Tunipole™ is terminated or how tall the tower is.

As far as antenna efficiency goes, performance follows theoretical prediction closely whether the wires extend halfway or the entire way up the tower. In other words, installing a Tunipole™ on the bottom 200 feet of a 400 foot tower does not mean only the bottom 200 feet radiates — the entire tower does.

The physical arrangement of the Tunipole™ on the tower can affect matching and transmission bandwidth. Our experts will recommend the most cost-effective arrangement for your station.

TYPICAL MECHANICAL-ELECTRICAL DATA

	UP-311-200	UP-351-200	UP-611-200	UP-651-200
Frequency Range	500–2500 kHz	500–2500 kHz	500–2500 kHz	500–2500 kHz
Power Rating (Typical)	15,000 watts	25,000 watts	25,000 watts	50,000 watts
Impedance Range	10–300 ± j350 ohms	10–300 ± j350 ohms	10–300 ± j350 ohms	10–300 ± j350 ohms
Lightning Protection	DC Ground	DC Ground	DC Ground	DC Ground
Windload (100 mph)	300 lb (135 kg)	600 lb (270 kg)	600 lb (270 kg)	1200 lb (540 kg)
Download	500 lb (225 kg)	700 lb (315 kg)	1000 lb (450 kg)	1400 lb (630 kg)
Weight	125 lb (56 kg)	200 lb (90 kg)	250 lb (113 kg)	400 lb (180 kg)
Insulation	Epoxy / Fiberglass (anti-UV coated)	Steatite / Epoxy / Fiberglass (anti-UV coated)	Epoxy / Fiberglass (anti-UV coated)	Epoxy / Fiberglass (anti-UV coated)

How does the Tunipole™ folded unipole antenna compare with my base insulated series-fed antenna?

It is superior in every respect. Field experience demonstrates bandwidths up to 100% greater than series-fed systems, and tests over an abbreviated ground system have shown significant improvements in efficiency. There is no reason to build a series-fed tower — and every reason to convert your existing one.

COMBIPOLE™ Multi-Station Folded Unipole

Now LBA folded unipoles may be used to feed two or three Medium Wave transmitters into one antenna tower. The unique Combipole™ permits independent feed of as many as three MW transmitters to one tower and provides independent impedance control at each frequency. Power levels to over 1,000,000 watts are available. Systems can be supplied to include towers, ground systems, and tuning/filter units.

What about construction and durability?

Tunipole™ folded unipole antenna systems are designed for long life. They are constructed utilizing UV-resistant fiberglass, aluminum or hot dip galvanized steel structure, heavy-duty steel-reinforced aluminum cable, and custom hardware. Careful attention has been given to corrosion prevention at dissimilar metal joints for long and stable operation.

FLEXIBLE ANTENNA IMPEDANCE SELECTION

Resistance and reactance parameters at the feed point are customer selected by physical unipole adjustment with a shorting stub. A wide range of impedances is possible. Existing Antenna Tuning Units can frequently be used with little modification.

TESTED AND PROVEN

Designed by broadcast consultants for the special needs of AM medium wave broadcasting worldwide, the LBA Tunipole™ folded unipole is the only system with a 60-year record of high performance. Hundreds of installations worldwide attest to the quality of the LBA Tunipole™ folded unipole antenna. All Tunipoles™ and Combipoles™ are backed by a conditional one-year warranty.

How difficult is installation?

Installation should only be performed by competent and properly equipped riggers. For an experienced installer, the procedure is simple and rapid. Many installations are made in less than eight man-hours. Adjustment and tuning is typically a one-day process by the station consulting engineer or appropriately skilled staff.

I want to install communications antennas on my tower — can I do that?

Yes. LBA developed the CoLoPole™ to facilitate installation of communications, cellular, and PCS systems on AM towers. Read more about AM tower co-location.

What additional systems and services are available?

Complete Tunipole™ folded unipole antenna packages are available to meet your needs. In new construction or station rebuilds, LBA Technology’s TTU series of Tunipole™ Tuning Units is an ideal complement to your antenna system. We can also recommend and supply conversion parts, as well as coils, capacitors, coaxial cable, copper ground wire, ground screens, and other RF supplies — providing a true one-stop resource for AM antenna system requirements.