DIY 2.45GHz Helix

[totonor]

Hello ,

I want to make an helix in 1010mhz.

I use this calculator :

http://jcoppens.com/ant/helix/calc.en.php

It says 6mm for the conductor diameter . If i use 2.5mm conductor instead of 6mm , will it be good ?

Thanks

[Mictronics]

For my 1240MHz helix I used 3.5mm/10mm˛ copper wire. Works fine, so 2.5mm will be ok.

[totonor]

Thanks a lot ,

For the reflector , shoud i made a circle or a square ?

Another question , i 'll made the helix on a pvc cylinder , should i remove it when the coil will be finished ?

Regards

[Mictronics]

A circle would be better in theory, in reality you will not experience a difference I think.

If you keep the PVC then you need slightly different dimensions. See http://www.rcgroups.com/forums/showp...06&postcount=4

[Mictronics]

Hugy, a quick simulation shows the following results:

Spacing - RHCP Gain - 3dB Beam width
28mm - 13.12dBic - 44°
18mm - 12.45dBic - 42°
10mm - 10.97dBic - 48°

[totonor]

Thanks a lot !

[hugy]

Thank you for the simulation. This means the calculator is faulty. It increases gain and beamwidth if you decrease the winding spacing.

[IBCrazy]

That's one thing about the helix: spacing will change it's gain and impedance. However this will also throw off the matching technique slightly. There is no real good calculator for it. You can only make some basic assumptions. Even modeling programs don't do a great job modeling the helical.

-Alex

[hugy]

Have you tried a helical with the windings almost touching it will make it a lot more compact and easy to handle. Maybe ad an extra turn to compensate for the loss of dbi.

[Mictronics]

Nope. But compared to a 1.3GHz helix I consider a 2.4GHz one compact and handy.