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.

Let’s now discuss antenna types…

In TV reception, there are typically 4 major types used; Log Periodic, Corner Reflector, Yagi and Bowtie, not in any particular order.

Log Periodic- Is the type of Off-Air Reception Antenna that you will see used by your Cable TV Company at their Head-End location. It is Highly Directive, slimmer than a Yagi and can tune to a range of frequencies with little variance in characteristic performance, and because it’s performance and specifications are highly repeatable and predictable, multiple units are used to form arrays of 2 or 4 of them combined together with commensurately predictable results. They are heavy, expensive and line of sight use of an array typically requires a tower. For these reasons, this antenna style is rarely seen outside of Institutional use.

Yagi- Is probably the most recognizable antenna type used in the widest variety of applications. Mostly used for VHF reception, it is elegant, simple and is a flexible platform for design modifications that would exhibit predictable patterns in reception, frequency bandwidth and gain. It can be tuned to a specific Frequency or range of Frequencies. The math of the physical construction is deeply rooted in correlation to the electrical wavelength of the Frequency desired. The size of the elements is a dead giveaway to clue one as to the frequency of use; as the frequency of use is lower, the size is greater (though some Low Frequency variants incorporate loading coils to reduce size).

Corner Reflector- Is widely used for UHF reception, but not readily recognizable because of its incorporation into antennas as a subcomponent. It is highly directive and tunable, and gain comes from some physical characteristics related to length. It has a small profile and wind load, yet is limited in gain as there are limits to the typical gain/size increase projections that other antenna designs enjoy.

The gain is primarily related to its efficiency, the long boom component is a key means to this end, as the multiple director elements attract and guide the signal towards the driven element. Whereas a variety of corner reflector designs all look the same in size and shape, the increase in boom length and number of director elements directly correlates to its gain potential.

Bowtie- Is respected as the Master of UHF reception due to the physicality of size. It uses more than one driven element to collect the signal, and the increase in the size of the reflector and number of driven elements (the bowties) directly impacts its gain characteristics. The size correlation is that compared to the electrical wavelength of the frequencies desired in reception. As UHF is higher in frequency and shorter in wavelength, a respectable size antenna can mathematically be gargantuan with respect to frequency, yet physically be manageable for installation. The design is unique to UHF however, as the translation to the larger wavelength of VHF frequencies lends itself impractical in size. For this reason, Bowties are poor performers with regards to VHF frequency reception, but absolutely the best for UHF. Small Bowties are the least obtrusive to aesthetics and are wide beam-width to capture sources of signal diverse in azimuth (direction). Large Bowties simply intercept a large portion of the signal wave as it passes by and is most efficient in its ability to funnel the signal through multiple Driven elements into the cable where you need it.

; ; ; ; ; ; ; ; ; ; ; Most TV antennas (99.9%) that we have grown accustomed to seeing these past decades are actually a combination of Corner Reflector and Yagi, with the long nose in front leading directly to the first reflector panels that physically comprise the Corner Reflector for capture of UHF signals, and the long outward elements bringing up the rear of the antenna comprising the Yagi component of the antenna for VHF reception. Now you can understand why when examining gain and range data for antennas, the differences in the same antenna are delineated along VHF/UHF categories. Two antennas in one is what you get; with the characteristics of VHF/UHF reception with same basic antenna design being so diverse.

Some antennas along this approach will further variate along two paths:

Those whose long VHF Yagi reflector components form more of a “V” shape as opposed to coming out from the boom perfectly perpendicular are shaping the reception pattern to have a broader beam-width, for those markets where the TV station have several Transmitter locations around town, close but not collocated, and

Those that incorporate Bowtie shaped components into the Corner Reflectors up front as to increase UHF gain and range.

I think at this juncture we can understand where the size and number of elements of the antenna directly correspond with the gain and range of the antenna (and detrimentally the weight and wind load).

That is why you will see the number of elements denoted in describing the performance of these styles of antennae. More elements and larger size equals more gain, weight and wind load.