Eine kompakte 6-Band Richtantenne für KW

Transcription

1 Eine kompakte 6-Band Richtantenne für KW Erste Erfahrungen mit einem zusammenfaltbaren Hexbeam von Oliver Durm (DL3SDW / N7SDW) Slide 1

2 Contents The following slides are an extraction out of the presentation 1st Experiences with a foldable Hexbeam which was presented at the monthly meeting of the HAM club of OVLudwigsburg (DOK P06) on Slide 2

3 Assembly of the folding Hexbeam Hints and Experiences Slide 3

4 Inserting the carriage bolts into the hub A piece of wood for supporting the assembly Slide 4

5 Inserting the carriage bolts into the hub Another piece of wood with a 7mm hole for supporting the assembly Slide 5

6 Inserting the carriage bolts into the hub Pressing the square section Of the bolts into Hub halves Slide 6

7 DL3SDW's approach of mechanical tuning... for a symmetrical shape Slide 7

8 DL3SDW's approach for mechanical tuning... The basic shape is a hexagon with 6 equilateral triangles α b a α c α α = 60 a = b = c Shape of the Hexagonal Beam Keeping b = constant at all triangles No bending of the spreaders possible Will (must) result in a symmetric look of the hexagon Slide 8

9 Mechanical tuning step by step 1/4 Mount the wire clips on each spreader at the start location which is suggested in the manual Distance d Default distance - out of manual DL3SDW Final positions of wire clips at DL3SDW`s folding antenna after electrical and mechanical tuning: 20m band: 17m band: 15m band: 12m band: 10m band: Slide 9 308,0 cm 237,0 cm 203,0 cm 170,0 cm 150,5 cm

10 Mechanical tuning step by step 2/4 Connect one dipole leg of the 10m dipole to the feeder elem_length Attach the wire to the 1st clip and STOP: (a) measure the distance d between centre of the wire clip and the outside of the feeder tube (blue arrow) (b) the mounting wire length from spreader to spreader (centre of wire clip's) is calculated as follows: elem_length = d+1.5cm Distance d 1.5cm (c) mark this length and click the element wire into the wire clip that this marking is at the centre of the wire clip Slide 10

11 Mechanical tuning step by step 3/4 (d) Now, measure the element_length to the next wire clip and lay the element into this next wire clip (e) by proceeding so, you ensure that all distances between the spreader stay constant and the spreaders won't bend to left or right side. (f) take the wire back to the feeder and tighten it with the screw. If it fits well, continue with the next element of the consecutive frequency band In case the wire is too short and you can't connect it with the screw to the feeder, move all wire clips 1cm towards the feeder and restart again measuring the distances as in (a), continue then as described in (b) to (f) In case the wire is too long, please continue in the following way (g) Slide 11

12 Mechanical tuning step by step 4/4 (g) If the wire is too long, bend it as shown on the sketch to determine the length 'half_delta_too_long' of which it is too long delta_too_long = 2 * half_delta_too_long (h) Now you can re-calculate the new wire clip position: move_wire_clip = delta_too_long / 6 (i) Move the wire clip's by the value you calculated in (h) away from the feeder Half_delta_too_long Restart at (a) by continueing so, your folding antenna will always look symmetrical and you achieve the optimum tension of the wire elements between each spreader Slide 12

13 Now, the antenna looks symmetrical Slide 13

14 Now, the antenna looks symmetrical Slide 14

15 Summary The Hexbeam as a folding antenna is Lightweight and compact for transportation Small wind cross section, however: let's see how it behaves at extreme weather conditions (e.g. rain with ice, snow) Versus time and continous UV light exposure Only about 3.20m turning radius Nearly equivalent to a 3-element beam in terms of Gain and F/B ratio No significant sidelopes Wideband no antenna tuner required Without any traps thus no Q-decreasing nesting place for little animals like bugs, spiders,... For up to 6 bands (20m.. 6m) The Allrounder for portable and permanent Installations Slide 15

16 Thanks for your attention Slide 16

17 Appendix Source of Information, Links Slide 17

18 Appendix & Source of Information Slide 18