m END FED ANTENNA - G0CSK

Transcription

1 Isular Isular 40m Trap 6.55m 80m Trap 8.54m 9.9m Mast Height Not Critical Groud Spike Coax Cable NOTES:- NOTES: At At, coax, coax ier ier coects coect atea atea (blue) (blue) braid braid coects coected brow brow spike. 2. spike. Each sectio of atea is iitially cut over size by 300mm, trimmed reduce SWR o each b startig with 2. 40m The b three sectio s first that, make up 80m ed sectio, fed atea fially are iitially 160m cut sectio over size by 300mm, cut reduce SWR If If is is ot ot very very coductive coductive add add supplemetary supplemetary radial radial isulated isulated s s o o act act as as a couterpoise. a couterpoise. ( 8 ( x 8 4m) x 4m) 4. To Tue atea Start with 40m sectio, adjust 80m sectio, fially tue 180m sectio. Soldered Atea Coax Cable RG58 Hole i Drai Pipe Coax Braid 2.5mm Dia Copper Fixig poit G8ODE TRAP DESIGN INFORMATION 80m Trap 23 turs RG58 o 40mm Diameter plastic pipe 150mm log 80m Trap 23 turs RG58 o 40mm Diameter plastic pipe 150mm log 40m Trap 11 turs RG58 o 40mm Diameter plastic pipe 80mm log 40m Trap 11 turs RG58 o 40mm Diameter plastic pipe 80mm log N.B. A very useful ol for coax-traps is a program by Toy VE6YP called "coaxtrap.exe". You ca dowload program from his website

2 Soldered Atea Coax Cable RG58 Hole i Drai Pipe 80m Trap 23 Turs RG58 40m Trap 11 Turs RG58 O a 40mm Dia former Coax Braid 2.5mm Dia Copper Fixig poit G8ODE Here are phographs two that were made usig this form of costructio. The Coax has bee taped over for additioal protectio, eds have bee sealed by first fittig cut plastic discs sealig se i with silicoe bath sealer 40 Metre Coaxial Trap 80 Metre Coaxial Trap N.B. A very useful ol for coax-traps is a program by Toy VE6YP called "coaxtrap.exe". You ca dowload program from his website

3 1.91MHz Plots Note: The Red & Blue colours are used simply emphasise vertical & horizotal compoets of atea curret. The X marks positio of traps. 3.55MHz Plots Lookig at curret distributio, it will be see that 1.92MHz Frequecy does ot cause eir of two traps become activated & atea behaves as a log MHz Plots Here 3.55MHz frequecy causes 80m trap operate electrically shorte atea. The curret i last sectio of atea is sigificatly reduced Here 7.05 MHz frequecy causes 40m trap operate furr electrically shorte atea. The curret i last two sectios is thus sigificatly reduced

4 3-D Far Field Total Radiatio Plot for 7.05 MHz. The 3.55Mhz &1.92MHz plots are very similar. The fuel i cetre gradually disappears. I all three cases maximum radiatio is at a agle of about 30 degrees.(see results below) MMANA-GAL MODEL RESULTS The model oly provides a idicatio of expected performace of this atea. I practice better SWR results & hece improved efficiecies ca be obtaied.

5 The traps for this atea ca also be made usig coils capacirs. E A Rule G3FEW (RAOTA 1487) who is a fellow member published this iformatio as part of his trapped Multi-b atea i RAOTA joural issue OTN89 also made article available o web as a PDF. The table below provides details of how make coils. A 40mm diameter plastic tube is used for former, a 100pf high voltage capacir tue trap for each of HF bs. He also suggests a way of makig a capacir from double sided glass fibre copper lamiate board (PCB).. For high powers i excess of 100 watts high voltage capacir should be used, because epoxy resi used for PCB material may become over stressed start breakdow. If capacir s value falls betwee 90pf 110pf atea Wires legth will eed alterig.. Alterate Method for makig Traps G8ODE RSARS 1691 RAOTA 2004 Soldered atea Wire Hole i tube 1.2mm eamelled see table below 40mm Diam Pipe 1mm glass fibre double sided Copper Lamiate (PCB material) For 100pF Copper area 35x60mm Importat 1-2 mm border o copper, avoid flash-over whe trasmittig Table 1. LC Trap widig details. -- E A Rule G3FEW (RAOTA 1487) T ra p F re q M H z T u r s uh C a p a c i r p F 10m m m m m m m