The Other Antenna


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The Kathrein/Scala HDCA-10 is a low-band VHF receive antenna covering channels 2-13.

The Kathrein/Scala HDCA-10 is a low-band VHF receive antenna covering channels 2-13.

Once you have delivered those off-air signals to your technical center, you'll likely have to split them in some way. (After all, you probably have multiple stations and you may have an HD Radio station or two or three.) Resist the temptation to use multiple BNC tees to split that signal. Instead, investigate the product line from Mini-circuits. Mini-circuits makes a wide line of passive RF power dividers: You decide on the number of output ports, the impedance of those ports and the connector type.

The cool thing about these passive power dividers is that you can also use them to add RF signals together. Just keep in mind that they exhibit the same loss whether or not you use them to divide or add signals. (For example, a four-way divider has slightly more than 6dB loss per port; if you use them to add RF signals, each signal going from output to input will still be weaker by 6dB).

Likely you will need a receive antenna to capture the National Weather Service or other VHF/public service channels. At least a couple of good options exist. You could consider the Kathrein/Scala K51262 or a Marti Electronics NMO-150K.

Application 2: Studio-to-transmitter link

Hopefully your facility has 950MHz band aural facility licenses. If so, you have quite a few options available to you as far as antenna suppliers go. One manufacturer practically camouflaged by name changes is now known as Gabriel (formerly Mark or Mark/CSI). Its standard products have been the 4', 6' and 8' grid-dishes (model numbers P-9A48GNU, P-9A72GNU and P-9A96GNU respectively). Marti electronics offers the SC-48, another 4-foot fully parabolic grid-dish. If you have a shorter hop or less of a need for the high amount of directionality afforded by the fully-parabolic antennas you could consider the Kathrein/Scala antennas: the PR-950B or even the mini-flector (MF950B).

The Kathrein/Scala PR-950B is for those who have a shorter hop or less directionality for a studio-to-transmitter link.

The Kathrein/Scala PR-950B is for those who have a shorter hop or less directionality for a studio-to-transmitter link.

One STL transmitter manufacturer sells a system that makes use of a duplexer, which is basically an array of filters that allows you to use one antenna for both receiving and transmitting. You could run with that same idea: Say for example you want to locate your own 900MHz ISM band transceiver at your transmitter site and another at the studio site. Another idea is the locating of an RPU receiver at your transmitter site, and backhauling the audio of same to your studio via a part 101 radio link. EMR makes duplexers that would allow you to assemble systems such as these: for example, the 66542. (Of course you would need one per end).

The K51262 is Kathrein/Scala's option for capturing the National Weather Service or other public service channels.

The K51262 is Kathrein/Scala's option for capturing the National Weather Service or other public service channels.

There is much more to this topic though. If you have a cluster of stations, with several licensed STL channels, all pointing at the same target, do you really need a transmit antenna for each? Or, say you make use of a two-hop system with an intermediate point. Are you charged for each antenna separately? If so you may want to consider an STL transmitter combiner. Get to know EMR Corporation. One example of its transmit combiners is the 66522, a two-way combiner. Insertion loss is no more than 2.4dB (make sure you include that loss in your path analysis and on your 601) and minimum transmitter separation is 500kHz.



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