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Wide band Antenna filters


Fred Salles

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Hi,

Are you using antenna filters on a regular basis? 

Whether on board of active antennas or as part of an in-line booster (for the RX of course).

I actually never had to use any, using mostly passive antennas with occasionally the gain booster included in the SL6 but now that I am about to buy very wide band Wisycom tx&rx (namely MPR54 and MTP60) and I need to buy antennas I am wondering if I should get some. Wisycom makes both passive and active antennas with on board filter, but they also make the BFA booster with filters so I am thinking to rather buy a set  of passive ones (2 omni and 2 directional) and if needed I will get 2 BFA. 

Any advise welcome.

thanks

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Well, I am not familiar with the exact use of filters for the antenna, but I am just assuming that they will prevent overload on the receiver. I suppose just like we use low cut at 60hz for example to avoid a loud 40hz to overload the preamp even if we cannot really hear it. If my tx are set in the 800Mhz range and a very strong signal from a nearby industrial area is around 1ghz the filter on the antenna would prevent  the receiver to overload before its internal filter. Does that make sense? 

Anyone more familiar with these please correct me.

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The Wisycom BFAs are excellent to have, I highly recommend them. You have a whole range of filter settings and wide range of signal boost and attenuation from -12 to +27dB in 1dB steps. Pricey but worth it. If you are getting new antennas anyway, I would get the Wisys with the BFA integrated, or get the BFA separately for more flexibility  

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1 hour ago, Constantin said:

The Wisycom BFAs are excellent to have, I highly recommend them. You have a whole range of filter settings and wide range of signal boost and attenuation from -12 to +27dB in 1dB steps. Pricey but worth it. If you are getting new antennas anyway, I would get the Wisys with the BFA integrated, or get the BFA separately for more flexibility  

Thanks for your input. Can you confirm that I would need 2 BFA ?

Yep pricey indeed, listed 900euros each excl.VAT!! But the LFA are 1100e each (=directive active+onboard BFA) and the LBN (passive) 310e, that's 1210e BFA+LBN and I can also get the omnis passive as well so that it is more interesting in the end.

Could you also give us an idea of how often you need to use the filter section of the BFA with a significant improvement ? 

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Yes, you do need two, one for each receiver antenna. 
I have them always in my signal chain and they are always on and set to a fairly broadband filter, I think it’s 530-698,  but I can verfiy later. That covers all my receivers and keeps Walkie interference out, which was my main issue. Since there are always walkies on sets and I never suffer interference from them anymore, this was a great improvement.
I change the filter settings rarely, like maybe once every 4 to 6 weeks, if there are issues, and will change back on the next location. I change gain/attenuation more often, but I‘m mostly happy with a 0dB setting, or a -3 when I‘m close to the set. 
 

 

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5 hours ago, Constantin said:

I have them always in my signal chain and they are always on and set to a fairly broadband filter, I think it’s 530-698,  but I can verfiy later. That covers all my receivers and keeps Walkie interference out, which was my main issue. Since there are always walkies on sets and I never suffer interference from them anymore, this was a great improvement.

Thanks Constantin, very valuable info!

Since I never had massive problem other than very occasionally without filters I never thought of hiring them before. Maybe these occasional ones could have been avoided!

 

On 3/24/2022 at 3:50 PM, BAB414 said:

I use filters from a company called Professional Wireless Systems that go from 470 to 608 MHz I believe.

Thanks BaB. these are fixed filter like this one, right?  https://www.professionalwireless.com/product/pws-in-line-bandpass-filter-uhf-470-616-mhz/

Do you also always have them on like Constantin?

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On 3/25/2022 at 9:00 AM, Fred Salles said:

Thanks Constantin, very valuable info!

Since I never had massive problem other than very occasionally without filters I never thought of hiring them before. Maybe these occasional ones could have been avoided!

 

Thanks BaB. these are fixed filter like this one, right?  https://www.professionalwireless.com/product/pws-in-line-bandpass-filter-uhf-470-616-mhz/

Do you also always have them on like Constantin?

These are fixed and are always in line in my signal chain. Note that they introduce 1dB of loss if I remember correctly. The company makes them in different flavors for different bands.

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On 3/24/2022 at 1:50 PM, BAB414 said:

Just note: Filters are different from attenuators. Both are handy to have. I use filters from a company called Professional Wireless Systems that go from 470 to 608 MHz I believe.

I am also using these Professional Wireless System filters. I have the 470 - 616 MHz. I have them on both my cart and in my small bag. They are helpful keeping my IFB (they are in the mid 600 MHz) to overload my Rx as they are pretty close to each other.

The Wisycom BFA is of course the deluxe version which i might get one day.

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