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LTE filters for TV antennas: What they are and do you need one?

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The airwaves above your house are packed with signals that usually live side-by-side with no problems, but sometimes interference can occur. When it comes to digital TV reception, cellular signals on nearby frequencies can mess up your picture.

Strong signals can disrupt and interfere with television signals causing pictures to momentarily break up or making the channel impossible to receive. In those circumstances, an LTE filter can help.

What is the LTE problem?

Television broadcasting in the United States is split between three frequency bands, with the majority of broadcasters using the UHF band.

UHF currently runs from 470MHz to 698MHz and includes channels 14 to 51, but it used to be wider. Until 2009, television broadcasting went up to channel 69 at 806MHz, but that upper portion was reallocated to cellular carriers to help them cope with surging demand for 4G wireless.

th shrinking bands 2 Rob Schultz/IDG

Demand for mobile broadband spectrum has slowly shrunken the TV broadcast band in the U.S.

That placed LTE signals directly adjacent to TV broadcasting and at frequencies that many TVs and antennas were designed to receive. Under most conditions, a TV will ignore those higher frequencies, but if the signals are strong enough, they can bleed over into the lower frequencies used by television stations and cause interference.

What is the solution to LTE interference?

An LTE filter is designed to stop interference by aggressively clamping down on radio signals outside of the TV broadcast band.

The filter sits inline with the antenna cable, so it only affects signals traveling between the antenna and the TV and won’t affect LTE reception for nearby phones and tablets.

The diagram below shows the signal response from an antenna with and without an LTE filter. The unfiltered connection (the lighter red) has strong signals above the 700MHz top of the broadcast TV band, but with a filter (the darker red) those signals are significantly reduced so they won’t interfere with TV reception.

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