Confused about Yagi's

[LukeB]

I tried doing some research and couldnt come up with an answer. I have received conflicting information about how a Yagi works. I know they are directional antenna's but in which direction?

Is it where the tip of the antenna is pointing? If the antenna is pointing to the east and the radials are pointing north and south, is my reception going to be strong to the north and south or to the east, in the direction that the antenna is pointing?

I always thought it was the direction that the antenna was pointing (east in example) but a friend of mine swears that his signal is strongest to the north and south in which the direction the radials point. Do some Yagi's work differently? Someone please help clear the air.

 

[KC0QNB]

Yagis are directional usually toward the opposite the feed point (where the cable hooks up)
or another way is the antenna is directional at the end where the shortest elements is.
Also your friend needs to know where the transmitter is, just because the users are in town A doesn't mean the transmitter is in the same place

 

[LukeB]

Basically, my friend doesnt know what he is talking about?

He claims he has it facing towards the transmitter but is receiving great on points perpendicular to where the antenna is pointing, which is what confused me.

 

[KC0QNB]

I wouldn't say your friend is not right, but here is a scenario our counties control station is in town, but the antenna and transmitter is about 7 mile south of town, there for I would point the antenna at the transmitter site south of town, Make sense?

 

[LukeB]

It makes complete sense...lol thats the impression i was under; the direction you point the antenna in is the best reception.

He claims that he is receiving the reception to the north and south meanwhile his Yagi is pointing west. He happens to be in close range to the transmitter site and is pointing directly at it. But he is hearing a fair distance away to the north and south while pointing west.

Thanks for clarifying.

 

[KC0QNB]

It makes complete sense...lol thats the impression i was under; the direction you point the antenna in is the best reception.

He claims that he is receiving the reception to the north and south meanwhile his Yagi is pointing west. He happens to be in close range to the transmitter site and is pointing directly at it. But he is hearing a fair distance away to the north and south while pointing west.

Thanks for clarifying.

Yagis do have some side reception capability but if he turns the antenna while receiving say a weather radio channel he "should" notice the difference, especially if the station is not real close.

 

[delta_p]

So I have to ask a question. I think I understand how on transmitting off a yagi the wave tends to be cancelled on the sides added to the front due the reflector and to a smaller extent the additional elements shaping it more toward the front of the antenna. But when recieving does it act exactly that way too? I can see how the thing can recieve fairly well to the side etc. but a little better when turned head on to the incoming wave. Maybe the friend just doesn't now he can get better signal to turn the antenna?

PP

 

[KC0QNB]

Not as noticeable in RX, but it does make a difference, remember most old school TV antennas, had to be pointed at the station for the best signal, Right?

 

[LukeB]

I will have to ask him again what his set up is and see if he understands the way these antenna's work. Maybe I have it wrong after all of this time...hahaha

 

[JnglMassiv]

But when recieving does it act exactly that way too?

Yep. Any passive component, here an antenna, will have the same tx and rx characterisitics. This is called reciprocity. It's why one need not worry about polarity when installing, say, resistors and coaxial cabling.

If you don't have a clear line of sight to your intended listening target, you might have to point your antenna in some weird directions.

 

[KE5MC]

...He happens to be in close range to the transmitter site and is pointing directly at it. But he is hearing a fair distance away to the north and south while pointing west.

Thanks for clarifying.

In close proximity to the transmitter and the gain of the yagi may be overloading the receiver. It may seem like poor reception, but is really better than the front-end and agc can handle. The reception in the side-lobes of the yagi is reduced and the receiver does not overload and sounds better.

Alternate possibility - slightly better than nothing.