On Tue, 26 Feb 2008 23:02:37 -0800 (PST), K7ITM wrote:
Let's see...500MHz to 1.05*500MHz = 525MHz; boom long enough to get me
about 10dBi over that range. I'll scale it to my particular
frequencies of interest, so any other ~5% bandwidth in that general
vicinity of frequencies would be fine too.

Cheers,
Tom

This is a Log Periodic design. Double booms, 1 inch square, spaced
1.4 inches c-c. Boom length ~55 inches.

Sweep for 500-525 MHz
Free Space Gain - 11.6 - 12.6 dBi
vswr 1.7:1.0

X is the position of the element along the boom.
Y is the length of each "half-element". With a double boom design,
one half of the dipole is mounted to one boom and the other half is
mounted to the other boom.

Coax attached to the front of the booms, shield to one, center to the
other. Do not run coax between the booms.

Booms can be electrically shorted to each other behind element # 1.


You don't have to be this accurate, my calculator defaults to 5
places. Simply convert lenghts to the nearest mm is the easiest.

x y
End 0
1 2, 5.78592,
2 6.16586, 5.61234,
3 10.2067, 5.44397,
4 14.1264, 5.28065,
5 17.9285, 5.12223,
6 21.6165, 4.96857,
7 25.1939, 4.81951,
8 28.6639, 4.67492,
9 32.0299, 4.53468,
10 35.2948 , 4.39864,
11 38.4618, 4.26668,
12 41.5338, 4.13868,
13 44.5137 ,4.01452
14 47.4041 , 3.89408,
15 50.2079, 3.77726,
16 52.9275, 3.66394,
End 54.9275

have fun

On Wed, 27 Feb 2008 22:29:01 -0500, wrote:

On Tue, 26 Feb 2008 23:02:37 -0800 (PST), K7ITM wrote:
Let's see...500MHz to 1.05*500MHz = 525MHz; boom long enough to get me
about 10dBi over that range. I'll scale it to my particular
frequencies of interest, so any other ~5% bandwidth in that general
vicinity of frequencies would be fine too.

Cheers,
Tom

Log-Yagi design. Four driven elements, reflector & director.
Probably about 8 dBi maybe.

Ele Length Position
R 1.019' 0
DR1 0.984' 0.168'
DR2 0.924' 0.266'
DR3 0.868' 0.359'
DR4 0.815' 0.446'
D 0.902' 0.742'

Split DR1-DR4 and transpose feed. Place hairpin at DR1 if needed
for matching.

On Feb 27, 8:06 pm, wrote:
On Wed, 27 Feb 2008 22:29:01 -0500, wrote:
On Tue, 26 Feb 2008 23:02:37 -0800 (PST), K7ITM wrote:
Let's see...500MHz to 1.05*500MHz = 525MHz; boom long enough to get me
about 10dBi over that range. I'll scale it to my particular
frequencies of interest, so any other ~5% bandwidth in that general
vicinity of frequencies would be fine too.

Cheers,
Tom

Log-Yagi design. Four driven elements, reflector & director.
Probably about 8 dBi maybe.

Ele Length Position
R 1.019' 0
DR1 0.984' 0.168'
DR2 0.924' 0.266'
DR3 0.868' 0.359'
DR4 0.815' 0.446'
D 0.902' 0.742'

Split DR1-DR4 and transpose feed. Place hairpin at DR1 if needed
for matching.

Thanks for both those designs. I'll have a look at them and see if I
can get reasonable modeling results, probably this weekend. I'd about
given up that anyone would have any designs to offer, and appreciate
that you put some effort into the replies.

Cheers,
Tom