Technical information all around the LADDERLINE

LADDERLINE

THE SX PRINCIPLE

COAX OR LADDERLINE FEEDERS?

AND WHAT ABOUT THE LADDERLINE-FEEDER?

 

LADDERLINE  

is the name of a HIGHLY EFFICIENT FEEDER for shortwave transmitting and receiving aerials. It is characterized not only by a minimum of RF-loss, but also by the possibility of reaching SWR values of 1:1.0 with ONLY ONE AERIAL, ON ALL BANDS!

The LADDERLINE, is a feeder of 2 wires guided at a certain distance in parallel. A condition for minimal loss is a wire distance of no fewer than 40mms with AIR INSULATION, the required spreaders and insulators must be specified near to the air insulation quality to reach by construction, surface and careful selection of basic materials and have to resist against influences of sun, wind and weather, and mechanical stress.

Homebrewing of such aerials up to now is accompanied by a lot of inconveniences. Home construction of spreaders resulted often in electrical and mechanical faults.

Our extended program of components is the best way to make homebrewing of parallel wire systems extremely simple! It has been designed in close cooperation with DL6SX and helps the NEWCOMER to ERECT LADDERLINE-FED ANTENNAS as quickly.

We are producing four sizes of spreaders for 40mms to 190mms wire spacing, which are following the same basic principle, as shown by this drawing!

1. At both ends, CARRYING FORKS are holding the wires in parallel position, assisted by GUIDER GROOVES. Stop bars are preventing the wires to slip out of the forks, even under stormy weather conditions! The construction of the carrying forks minimizes the risk of wire fractures!
2. In the center of our spreaders a hole of 4,2mms or a circular groove (SP-50!) helps to guide the ladderline by a thin rope around abstacies, forming a soft curve!
   
   The hole together with the stop-bars is previewed to screw 2 spreaders together - 90deg for 4-wire-systems - or 3 spreaders for 6-wire-systems with the adapter ASP-16, which is necessary for the 60deg-positioning in this case.

Our components are manufactured exclusively with "Bayer"-compound materials, protected against extreme climatic and mechanical strain! The temperature range is -50deg to +90deg C !! The normal colour is black for being "invisible".

THE SX - PRINCIPLE

Is to be understood as an ideal combination of design, constructions and manufacturing of components for HF-applications, which has to follow:

1) careful selection of the basic materials for:  

2) Design and construction for: 

1. The insulator IS-120 is made for hooking it in the antenna-wire, no need to pass through! But it can be used for stabilizing a ladderline position by hooking in the parallel wires and the 2 bows are for a stretched suspension which helps to avoid lateral movements. In this case, the spreader SP-120 combines with IS-120 by its identical length!

2. The insulator IS-150 can be used as a coil-form too, for electrical prolongation of wire-antennas f. i. DL7AB without cutting the wire.

3. The 50mm-spreader SP-50 together with the center insulator ISB-6515 are an ideal kit for vacation antennas, easy to built.

4. Our spreaders SP-120/SP-150 and SP-200 can be screwed together in 60 or 90deg. angle, forming 4-wire-feeder-systems (90deg) and 6-wire-cage-antennas with high efficiency (60deg).

5. The anchor MAB-22 is in same time a perfect center-insulator for a 2 x 10-15m fan-dipole, using 2 x 4 wires. These wires are supporting the center pole in same time. Such an antenna with a 12m fishing rod is a good efficiency circular radiator, for 80 and 160m too.
   Advantage: very easy to erect in fieldday and vacation activities.  

Our SPREADER/INSULATOR-SYSTEM avoids complicated pass through work for the antenna wires and allows to built complicated systems without time consuming labor and repair or reconstruction of your antennas is very simple and easy to do! All spreaders and insulators remain in perfect condition after many years of use, due to the basic materials!

 

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COAX - OR LADDERLINE-FEEDERS?

Both systems have their typical characteristics which we describe as follows:

COAX-FEED 

 BUT 

• Matching becomes difficult if the antenna must operate out of the resonant frequency: a high SWR results accompanied by RF on the shield surface!

•  Trying to improve this situation by a tuner means not improving the cable SWR but only the match to the TRX-output! High SWR remains for the coax causing additional loss to the typical cable loss!

• By this reason, a coax-fed antenna in use for all bands is problematic! It works fine only, if a tuner is placed directly to the center of the dipole: in such application, the cable follws its destination as a travelling waves feeder with a minimum of loss and the dipole can be used for all bands.

•  This special solution can be avoided by using multiband-antennas like W3DZZ. This kind of antenna offers multiple halfwave-dipoles to the coax-feeder, but varying the frequency out of the resonant frequencies means not only mismatch but is more critical due to the antenna construction.

 

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AND WHAT ABOUT THE LADDERLINE-FEEDER? 

• This very advantageous system must be used with a symmetrical antenna tuner for reaching top results! Non symmetrical tuners with balun 1:4 for a symmetrical output is to be considered only as a provisional solution, because it requires a nearby matching impedance to the balun and this depends from the operation frequency: Mismatch causes high loss for the balun, heating it up, or a good match is not possible!

• A balanced or symmetrical tuner allows to tune the system antenna/ladderline together: Standing waves on the ladderline are causing no loss, a contrast to a coax-feeder! This system is tuning the antenna to all frequencies, the resonance of the dipole is not important.

• The ladderline, a two-wire-feeder, has a very small lateral radiation, depending from the spacing of the wires. This effect is of no importance for the daily ham-activities. But if someone wants to do more: there is a good selection of spreaders from 50 to 200mms available! The better feeder is a 4-wire-system: the capture of QRN from the neighbourhood is minimized, and it is easily made by crosssing two spreaders by screwing together at 90deg angle!

• Such a tuned antenna can be made of low-priced industrial stranded wires: an eventual prolongation of such wires by strech is easily tuned out!