Hi all

I want to build a relatively small & cheap Airband Yagi for receiving
only. I have found the Tape Measure Yagi page:

http://home.att.net/~jleggio/projects/rdf/tape_bm.htm

and that seems like a good starting point so have got the bits I need
for that (tape measure 25mm width, wooden beam and RG58 Coax).

I have also found this YAGI design page:

http://www.k7mem.150m.com/Electronic.../yagi_vhf.html

that looks like it will give me the spacings I need.

However it leaves me with some questions:

What center frequency should i use? Well I guess that depends on the
bandwidth of the YAGI I build, and i have no idea about that, is it
1Mhz, 10Mhz is it balanced +10 and -10 or is it +2 and -10, etc. The
main frequency I want to receive is 122.7Mhz, airband is 108 to 137 I
believe.

I read that for a tape measure yagi I should use an element diameter of
roughly half the tape measure width to put into the calculations - is
that ok?

The YAGI I am intending on building is about 6 elements, limited really
by the practical boom length, however 'officially' this is to small for
the calculator above as it is designed for 'long' yagi's - is the
calculator above still ok?

The Tape Measure Yagi uses a single straight driven element with a
hairpin for matching. The calculator above suggests using a folded
dipole with a piece of coax for the matching network. Can I use a
single straight tape measure driven element with the calculations from
the K7MEM page? If so what do I need to do with the 'hairpin' matching
network, how long does the hairpin need to be?


I appreciate there are a few questions here, and that it isn't an exact
science, so all comments, suggestions, answers etc welcome.

Thanks
Kev