Antenna Comparisons

In the course of trying to choose the optimal antenna we often find ourselves comparing manufacturer's specifications about gain, which are all too often sparse or expressed in inconsistant units of measure.  Or worse, relying only on marketing bullets claiming  "best deep fringe".

An alternative approach is to simply compare measured signal levels of one antenna to another.  If we do this on a number of different antennas, let's call 'em A, B, C, and D, and we find that A is better than B, and B is better than C, then it follows that A is also better than D.

So the links below provide antenna comparisons of relative field performance of a few popular VHF and UHF antennas. 

Antennas Direct 91XG vs Winegard PR9032  Channel Master CM-4228 vs Antennas Direct DB8
Antennas Direct 91XG vs their New DB8 Channel Master CM-4228 vs Winegard HD-8800
Antennas Direct DB8 vs Winegard HD-8800 New Channel Master CM-4228 vs Old CM-4228
New DB8 vs Old DB8 Channel Master CM-4228 vs SuperQuad
Y10-7-13 vs new Antennas Direct C5 Winegard HD7698P vs Y10-7-13 and PR9032
8-Bay Shootout  - CM-4228, DB8, HD-8800 8-Bay Shootout  -  Revisited for VHF !
Hi-VHF  NEW!  Stellar Labs 30-2476 vs Y10-7-13

Some "relative" Measurement Discussion
Consider the goal of finding the tallest person in a class.  If we knew each persons exact height, measured precisely in a common unit of measure such as inches or centimeters, we could easily identify the largest height from a form or chart.  But what if some were measured in inches, some in centimeters, some in "hands", or some were measured with shoes on, and some with shoes off?  If we only had the written information the choice we make could easily be the wrong one.

But if we actually had the students themselves available we wouldn't need to measure.  We could just stand them next to each other and visually identify the tallest; even if we had them available only two at at time!  As an example consider Alice, Billy, and Jane.  If we stand Alice and Billy next to each other and Billy is shorter, and separetely we stand Billy next to Jane and Jane is shorter, then it follows that Jane is also shorter than Alice, and thus Alice is the tallest.

Likewise in the comparisons here, various pairs of antennas are compared to each other.  These are comparisons of relative antenna performance.  It actually doesn't matter what the units of measure are, or even whether the measurement device is highly calibrated.  We only need to use the same device and with identical condtions to discover whether the signal level received by one antenna is greater or less than the signal received by the other. 

Relative and real world field measurements therefore remove numerous metrics typically found in various manufacturer's specifications.  Since such published specifications do not adhere to any industry or organizational standards one can easily be comparing apples to oranges.  I.e., what were differences in the antenna range(s) at which the measurements were made?  How accurately were all losses of baluns, cables, etc., taken into account?  How carefully was the manufacturer's instrument calibrated?  What was the instrument's precision?  And, in particular, what units were cited gain numbers expressed in, (dBd or dBi)?

For the record:

- All measurements of antenna pairs here are made back to back, as quickly as possible, in order to minimize the error contribution from time variant environmental conditions.
 - The receive transmission path consists of about 12 feet of Belden 7916A RG6 as down lead, a Kitz Technologies (1dB NF) amplifier whose gain was measured to be 20dB and flat as a pancake across the combined VHF/UHF spectrum, followed by another 8 feet of RG6 to the spectrum analyzer.
- In all cases, antennas were tested with their stock baluns, whether built in or supplied as a 300 to 75 ohm matching transformer.
- Height was about 15' above ground level.
- From measurement to measurement, the antenna under test was rotated to produce maximum amplitude across all channels within the bandwidth span (not necessarily maximum channel flatness of any one channel).
- Also from one antenna comparison to another the vertical scale of the analyzer may change; e.g., 10 dB / division or 5 dB / division.  But it is not changed between measurements of antennas within a comparison set.

In other words, a lot of care was taken to insure that the predominant variable between comparisons was the antenna itself.

And A Few More Technical Notes About The Measurements
The following notes attempt to clarify the measurement environment, conditions, and definitions.