Bygge av antennen crosshair

Jag tänker försöka bygga Ibcrazys crosshair antenn. Den är lite lättare än pepperboxen att ta med  på fältet. Dessutom har den tydligen en jäkla punch och kan lätt tränga igenom väggar, träd byggnader, vilket är en önskan jag har.

Har införskaffat galvad 7mm plåt 27*27cm och kopparrör till balunen som ska avstöra andra signaler eller multipathing (När radiovågor studsar tillbaka, släpar efter eller helt enkelt att det finns liknande frekvenser i området)

Länk till Ibcrazys byggsida

Crosshair antenn

I did exactly what Alex suggests, plug in the numbers in his equations.

I give below the dimensions for 1280MHz, quoting Alex's original posts, where calculations and unit conversions are applicable, for the metric folks : the figures with the three decimal digits are the dimensions in mm.

... Copper tube either (¼” or 3/8”) 6.350 or 9.525

...Wire diameter (in inches = 42/f in MHz to 60/f in MHz) 0.833 to 1.191

...Height over reflector in inches = (2350/f in MHz) 46.633

...Length of copper tube = (2933/f in MHz) 58.202

...Size of reflector panel (in inches= 8800/f in MHz to 17500/f in MHz (larger reflector increases gain and F/B ratio)) 174.625 to 347.266

...Short leg length (in inches = 2490/f in MHz) 49.411

...Long leg length (in inches = 2945/fin MHz) 58.440

...For this tutorial I am building a 1280MHz Crosshair. I am using (.035") 0.889 Welding wire and RG316 cable

...Make a cross across the panel. Drill the center out on solder in your copper tube such that only the height calculation protrudes (2350/f in MHz) 46.633 if you plan on using a balun

...Now drill 4 holes on the “X” to accommodate your nylon bolts. I placed mine at (1800/f) in MHz 35.719 away from the center, but this is not critical.

...Now measure down from the outside INSULATION ¼ wavelength (2933/f in MHz) 58.202 and remove the outer covering at that point

...The measurement from the top of the tube to the base of the reflector should be about (1/16”) 1.588 less than your height (hence=45.045mm) so your elements can clear it.

...Now strip as much insulation off the center element as possible without it shorting out to the shield. You should have about (1/16”) 1.588 of insulation sticking out of the cable at this point. Tin both the center element and the shield. Trim the shield back very short so that only about (1/8”) 3.175 or less is sticking out the side.