Connecting two antenna to 1 receiver

[sparer]

What is the effect of connecting two omni antennae to a single receiver? The antennae are not close enough to inter-react and operate at 433Mhz at low power.

Thanks

 

[dknguyen]

What is the effect of connecting two omni antennae to a single receiver? The antennae are not close enough to inter-react and operate at 433Mhz at low power.

Thanks

It probably won't work as well since there will be destructive and constructive interferrence between the two antennas, and the impedance also will no longer be matched.

 

[sparer]

It probably won't work as well since there will be destructive and constructive interferrence between the two antennas, and the impedance also will no longer be matched.

Could you explain destructive and constructive interferrence
Thanks

 

[Externet]

Yes, go ahead and connect both antenas, No interactivity will happen.
You can even connect four, paralleling a pair of two in series if you want to preserve impedance that may not be needed with modern receivers.

 

[Mikebits]

Not only will two antennas create a 2:1 impedance mismatch or worse without a splitter or some other matching network; the phase delay of the two signals arriving at the mixer (Depending on antenna spacing) will create unwanted mixing products. Question is, why would you want two antennas?

 

[crutschow]

Truckers often have two dipole whip antennas, one one each side of the cab, connected to their CB radio. The antennas are apparently tuned or have a matching network so that they provide the proper impedance to the radio. The two antennas generate a somewhat directional beam to the front and back which gives them greater range to other truck radios (which are likely located down the road in front or back of them).

 

[Mikebits]

Truckers often have two dipole whip antennas, one one each side of the cab, connected to their CB radio. The antennas are apparently tuned or have a matching network so that they provide the proper impedance to the radio. The two antennas generate a somewhat directional beam to the front and back which gives them greater range to other truck radios (which are likely located down the road in front or back of them).

Most likely, nothing more than a marketing ploy, at best it would add signal loss to the system. Then again, I could be wrong but I remain skeptical.

 

[Hero999]

It's possible to use two monopoles to form a dipole.

 

[crutschow]

Most likely, nothing more than a marketing ploy, at best it would add signal loss to the system. Then again, I could be wrong but I remain skeptical.

I understand your skepticism, there's a lot of electronic snake oil out there. Here's an article which suggests that, depending upon the antenna spacing and with proper coupling and equal cable length, there will be some directionality.

 

[sparer]

Not only will two antennas create a 2:1 impedance mismatch or worse without a splitter or some other matching network; the phase delay of the two signals arriving at the mixer (Depending on antenna spacing) will create unwanted mixing products. Question is, why would you want two antennas?

i'm using a 433Mhz key fob and I need to pick up the signal in two specific areas which are only 5 metres diameter each. The receiver will be desensitised to limit the range

 

[jamied_uk]

on 27 mhz and modafieing a antener switch box so that the swich is innactive and that it is resoldered so that both anteners are wired to 1 transciver will this increase range on tx and rx (all obstacles aside, like spacing inpedance swr etc). will it be better or will it be worse?

 

[dknguyen]

It will be worse due to impedance mismatching and interference between the antenna signals on both transmit and receive.