In article , Craig wrote:
intends etching the antenna onto a printed circuit board and in a
subsequent E-mail he asked whether the width of the foils should be
the same as for regular rod elements.


Warning -- the following is reasoned guesswork before my second cup of coffee...

Since it is not really the width of the rod elements that is important, but
rather the surface area (derived from the circumference 2*pi*r), I would think
that the width of the foils on the pc board should correspond to the
circumference of the rod elements, and should be calculated as Diameter*pi

I read about PCB strip antennas years back. From what I recall (subject to
correction of course) the bandwidth of the device is a function of strip
width (to a limit of course.) Also, if the strip is too narrow, the antenna
impedance will be skewed. I suppose that's due to the velocity factor of the
etched conductor. It's been quite a while since I've read up on any of this
so my menory of it might be severly distorted and if so, please accept my
apologies. An hour of surfing and searching should yield more than enough
info.

Cheers,
Pat

I wonder if the velocity factor, i.e. length, in the dipole would be
affected by the dielectric constant of the PCB?

I know that in microstrip transmission lines the Vf is inversely
proportional to the square root of the dielectric. This would be an
antenna with two different dielectrics; one, air: second PCB.

An alternative to etching the antenna, leaving copper for the antenna,
would be to etch the antenna away leaving the remainder of the copper
and tuning it as a 'Slot' antenna. This might have promise!

Deacon Dave, W1MCE
+ + +

Craig wrote:

A passing acquaintance of my wife's has E-mailed me for assistance
with calculating the element lengths for a UHF dipole he wishes to
build. I gave him the required information, however, he apparently
intends etching the antenna onto a printed circuit board and in a
subsequent E-mail he asked whether the width of the foils should be
the same as for regular rod elements.

In any event, in my very limited experience, I've never heard of
etching antennas onto a circuit board. Is this really possible, and if
so, can I direct him to a suitable web site with more info.

Craig

"Dave Shrader" wrote in message
...
I wonder if the velocity factor, i.e. length, in the dipole would be
affected by the dielectric constant of the PCB?

Absolutely. Also the loss factor.

I know that in microstrip transmission lines the Vf is inversely
proportional to the square root of the dielectric. This would be an
antenna with two different dielectrics; one, air: second PCB.

Yes

An alternative to etching the antenna, leaving copper for the antenna,
would be to etch the antenna away leaving the remainder of the copper
and tuning it as a 'Slot' antenna. This might have promise!

Monopole, Yagi, LPDA and Patch are all commonly done on pcb material.