Splitter or Two Antennas?

[searingxheretic]

Greetings,

I have decided to build an off-center dipole for scanner receiving. This will be placed indoors due to my housing situation. I have the following question and would appreciate some feedback.

I plan on using both of my scanners, one for my local 800mhz trunked system, and one for mil air monitoring.
I was planning on using one antenna and split it to both scanners. After reading about bleeding, etc. when using one antenna split to two scanners, I am now considering just building two dipoles.

Ultimate question: if the dipoles are placed in close proximity, will each one cause a receiving dead spot in the direction of the other? Would it even be worth my time to build two, should I just deal with the db loss and just split it? Using a multi coupler would be the best option, I know, but they're to expensive for me at the moment.
Any feedback is appreciated.

Sent from my cm_tenderloin

 

[reconrider8]

no expert built i would build 2 for the fact that both will be closer to their actual frequency range that they will scan therefore better all around reception

 

[popnokick]

OCFDs are so simple and inexpensive to make that I can't think of a reason not to build two of them. Far less cost than a multicoupler. And not impossible that you might get some interaction between two scanners split from one antenna, but very unlikely. But if you make two antennas you'll minimize chances of any interaction even if the two antennas are near one another. Nonetheless you should keep them at least a few feet apart.
However, I have only one OCFD and use a cheap 75 ohm splitter to feed two scanners. Works just fine.

 

[LtDoc]

I honestly doubt if two antennas 'close' to each other are going to cause a 'blank' spot in reception, or affect each other at all. I won't say it can't happen, but it they aren't fairly close in design frequency (and they wouldn't be), then they will tend not to 'see' each other. How far apart? Beats me. At least enough so that they won't touch?
- 'Doc

 

[shortride]

I think the only time 2 antennas close to each other will create an issue is when you are TXing.

 

[jim202]

The real facts of the case here are to not use a splitter. The reason being is that the law of physics and electronics boil down to the splitter causing a 3 db loss in what ever your trying to hear. This means that you just lost half of the signal strength by using a splitter.

As for the inter action of the 2 antennas, it shouldn't be an issues with some separation. This again boils down to not having both antennas right next to each other. Not so much as they will effect each others antenna pattern, but to limit the radiation each scanner does emit.

Like it or not, all radios do generate a signal that can be heard on another receiver. This signal will vary in strength, depending on how well the radio was designed. Even the high priced Motorola radios that the public safety agencies use generate a signal that can be picked up by other radios. This signal I am talking about is when the radios are in the receive mode.

These signals are generally very weak and won't be heard over any great distance. However, I have seen a scanner cause all sorts of problems to public safety radio systems. Have even been involved in tracking down the location of some of these really bad radiated signals. Normally with a scanner, the signal shows up as a pulsating signal. As the scanner goes through the different channels in the scan list, there may be one channel that will cause a signal to land on the channel that is important in the area and as such becomes a problem.

Now don't get all wound up about these radiated signals. Most of the problems have been reduced with the newer scanners. But it can be an issue if something happens to the scanner. Going inside the scanner and making a wiring change could cause it to start sending out a signal strong enough to cause problems. All I am saying here is to be aware that issues can crop up.

 

[searingxheretic]

Thank you all for the feedback. I will give the two antennas a shot. If I come up with any issues, I'll post them for others to avoid lol. Thanks again!

Sent from my cm_tenderloin