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Yagi Frequency
Posted: Fri Jun 16, 2006 5:18 am
by Iguana
Hi guys,
I got an Yagi 5 element vhf antenna, and I don't know how to calculate the anteenas frequency cause antenna based on 2 dipoles (trombone and reflector) that means that the reflector phase is 90 degrees.
Thanx
Antenna frequency...
Posted: Fri Jun 16, 2006 8:26 am
by Tom in D.C.
Looks to me as if the 80.5 cm element is at 177 mHz.
(80.5cm/2.54cm to the inch =31.7 inches)/12 in. to the
foot=2.65 feet.
468/177mHz=2.6440677 feet for a halfwave at this
frequency.
You can do the math for the longer element by changing
the 80.5 to the longer dimension.
How they interact I don't know.
Posted: Fri Jun 16, 2006 9:02 am
by Iguana
I think that 177MHz it's impossible its not commercial.
I have tried to do the same calculations.
Some history:
This antenna manufactured before 15-20 years and it was connected to repeater at Eilat city in Israel. As I know at theese years the most popular frequencies were 136-144 Mhz @25 kHz bandwidth.
Other option that antenna is for UHF... I will check it....
Thank you very much for the information!
Maybe some one have the datasheet for this model ???...
Posted: Fri Jun 16, 2006 3:41 pm
by 440roadrunner
I submit that without figuring the inter conductor spacing and diameter, the formula for length won't work, and probably not even then without reverse engineering the thing.
UHF? Not on your life
What do you have to test with? Any test equipment? reflection bridge?
Posted: Fri Jun 16, 2006 6:01 pm
by RFguy
That yagi...
Posted: Fri Jun 16, 2006 6:06 pm
by Tom in D.C.
I guess I was close enough for government work, as they say.
I've never gotten involved with or done any figuring on what is
apparently a log periodic antenna.
Posted: Sat Jun 17, 2006 12:30 am
by Iguana
Thanx a lot guys !!!!!