Stay Tuned! de JR2BJE

Each antenna performance changes anyhow, if I set up 2 antennas in tower ? I examine to set up 2 antennas for 21 MHz and 24 MHz.At that time, the most anxious about that a mutual antennas interfere to each other and is to make a mutual antenna performance be inferior. I try to examine whether that is the bset, when I set up antennas for any direction or not, in order to minimize an interference of a mutual antennas. Generally, the interference of a mutual antenna cause loss of gain on higher frequency's antenna. Not only a gain change of an antenna, I try to examine the comparison that how a beam pattern changes.Calculated antenna model is as follows.

5ele Yagi for 21MHz up 24 meters high
5ele Yagi for 24MHz up 20 meters high

For my case, I select same direction ( without an angle difference ) as better beam patterns. Anyway it dpends on you.

Here are calculated results.

Angle difference	Gain:(dBi)	F/B:(dB)	El:(degrees)
		21MHz
Single as reference	15.58	22.95	8.1
0 degrees	-0.12	-0.24	0
30 degrees	-0.11	-1.14	0
45 degrees	-0.11	-1.42	0
60 degrees	-0.15	-2.06	-0.1
90 degrees	-0.25	-2.88	-0.1
		24MHz
Single as reference	15.80	18.77	8.2
0 degrees	-0.91	-0.75	0.3
30 degrees	-0.65	0.19	0.2
45 degrees	-0.44	-0.82	0.2
60 degrees	-0.29	-1.98	0.1
90 degrees	-0.09	-2.12	0.1