The first key to any reception is to get above obstructions that exist between you and your target, as radio frequency reception of any kind (satellite, microwave, Radio and TV) are for the most part "Line-of-Sight" dependant. The fact that some receptions occur without line of sight is due to phenomenon not applicable in this discussion. As you increase your target distance, you increase the territory you must account for in maintaining line-of-sight. What tall building and air traffic exist in this corridor, no one can account for. Aircraft are very good at messing up reception for a number of reasons, even when flying way above the path, again removed for clarity in this discussion. Height, is therefore key in optimizing your ability to capture the best line-of-sight possible to your target.
Small Omni-Directional Antennas have a useable Reception Range of up to 35 miles.
Most Omni Directional Antennas are comprised mainly of a simple Loop Antenna turned back on itself into the shape of a circle on its side. Other Designs can be as simple as Modified "Rabbit-Ears" with or without a reflector to moderately increase Gain or Directivity. The Latest Designs are Loosely based on Printed Circuit Board Technology, where the tracings of the conductor laid on the Board or Film are laid with Physical Characteristics that attract and tune to the frequency range of the signals desirous for reception. Whereas most other TV antennas' gain is attributed to its directivity and the Focus of Beamwidth that is inherent with their rather large physical characteristics, Omni's have little gain compared to a simple dipole, and rely primarily on being in proximity to the Stations desirous of reception and/or amplification (either internal or external). As Interference and Strong signals can overdrive amplifiers and negatively impact Signal Reception, Antennas like these are used mostly in Mobile applications such as; Mobile homes, Trailers, Buses and Watercraft... Where the TV station location is unknown, multi-directional or constantly changing with locale. Home and Building permanent TV Antenna installations should consider other options first before considering small Omni's, unless the proximity to, and location of the TV Broadcast Stations are within the attributes of these Antennas.