10/23/09

Comparing some commercially available antennas

Antenna marketing is a racket in that the less honest you are, the more antennas you sell. (Nobody goes to court over a TV antenna.) Gain figures published by antenna makers are mostly useless, except maybe for comparing antennas by the same maker. The data for all of the charts in this section came from computer simulations of the antennas. The author performed the simulations.

Why computer simulations? (non-essential reading) A few years ago QST, which is the principal publication of the HAM radio community, announced that they would no longer accept advertising for antennas if the ads contained gain figures that were measured experimentally. Henceforth any such gain figures would have to be the result of computer simulations. There were two big problems with the experimental data: 1. The experimental antenna is affected by its surroundings. Computers can do true “free space” modeling. 2. The process of choosing the surroundings encouraged overly favorable choices. Most of us would call it cheating, but they justified it to themselves by the belief that their competitors were doing it. The program used for these simulations was NEC-4/EZNEC4 by Lewallen (W7EL), which is one of the programs approved by QST. Data points were produced every 12 MHz (UHF) or 2 MHz (VHF). Some problems were encountered which necessitated approximations, so the data is not highly accurate. But the author stands behind the principal features of the graphs and resulting conclusions. The antenna model files are available for viewing. (The files are at http://www.hdtvprimer.com/SIMS/ . Go first to the file README.TXT.)

Raw Gain for some common UHF antennas

A Small indoor loops

B Zenith Silver Sensor indoor LPDA

C Double-Bow

D Televes DAT-75 Yagi/Corner-Reflector

E Winegard Square Shooter

F Winegard SS-3000 Indoor Directional Antenna

G Winegard PR-9032 Yagi/Corner-Reflector

H Winegard PR-4400 4-Bay

I Winegard PR-8800 8-Bay

J old Channel Master 4221 4-Bay

K Channel Master 4242 VHF/UHF Combo

L Channel Master 4248 Yagi/Corner-Reflector

M AntennasDirect XG91 Yagi/Corner-Reflector

N AntennasDirect DB-2

O AntennasDirect DB-4 4-Bay

P old AntennasDirect DB-8 8-Bay

Q Antennas Direct ClearStream 2

R Antennas Direct ClearStream 4

S MegaWave Wideband Indoor Antenna

AA old Channel Master 4228 8-Bay

BB Channel Master 3671B VHF/UHF Combo

CC Channel Master 2020 VHF/UHF Combo

DD Channel Master 3018 VHF/UHF Combo

EE AntennaCraft HBU44 VHF/UHF Combo

FF Winegard HD-7698P VHF/UHF Combo

Raw gain is the true gain, as gain is defined. But a fraction of the power is going to be rejected by the transmission line because of an impedance mismatch. This rejected power gets retransmitted. What is left is the net gain. The following graphs are the ones you should pay the most attention to.

Net Gain for some common UHF-only antennas

A Small indoor loops

B Zenith Silver Sensor indoor LPDA

C Double-Bow

D Televes DAT-75 Yagi/Corner-Reflector

E Winegard Square Shooter

F Winegard SS-3000 Indoor Directional Antenna

G Winegard PR-9032 Yagi/Corner-Reflector

H Winegard PR-4400 4-Bay

I Winegard PR-8800 8-Bay

J old Channel Master 4221 4-Bay (3021)

K Channel Master 4242 VHF/UHF Combo

L Channel Master 4248 Yagi/Corner-Reflector (3023)

M AntennasDirect XG91 Yagi/Corner-Reflector

N AntennasDirect DB-2

O AntennasDirect DB-4 4-Bay

P new AntennasDirect DB-8 8-bay old DB8

Q AntennasDirect ClearStream 2

R AntennasDirect ClearStream 4

S MegaWave Wideband Indoor Antenna

Winegard HD9095P

Net UHF Gain for some common combo antennas

A Small indoor loops

AA new Channel Master 4228HD 8-bay

old Channel Master 4228 8-Bay

BB Channel Master 3671B VHF/UHF Combo

CC Channel Master 2020 VHF/UHF Combo

EE AntennaCraft HBU44 VHF/UHF Combo

FF Winegard HD-7698P VHF/UHF Combo

Click on the antennas above to see more data about each antenna.

The 4242 and 3018 represent typical Yagi/Corner-Reflector UHF antennas that are part of a VHF/UHF combo. You can estimate any other unknown such antenna from these two. Just find the length of the UHF part of the boom of the unknown antenna (measured from the intersection of the corner planes to the front-most director). Comparing this length to the 4242 and 3018 will let you estimate where the plot for the unknown lies in the above graph.

The 4242 has a 87“ boom (UHF part).

The 3018 has a 57“ boom (UHF part).

Raw gain for some common VHF antennas

A Rabbit ears – 40” 45°

B Winegard YA-1713 Wideband Yagi for VHF 7-13

C Winegard YA-1026 Wideband Yagi for VHF 2-6

D Wade single channel Yagis

K Radio Shack VU-75XR VHF/UHF combo Radio ShackVU-75XRVHF/UHF combo

L Radio Shack VU-90XR VHF/UHF combo

M Radio Shack VU-120XR VHF/UHF combo

N Radio Shack VU-190XR VHF/UHF combo

AA Channel Master 4228

BB Channel Master 3671B VHF/UHF combo

CC Channel Master 2020

DD Channel Master 3018

EE AntennaCraft HBU44

FF Winegard HD-7698P

Explanation (non-essential reading) Why show raw gain when net gain is what is important? 1. If atmospheric noise exceeds receiver noise then the raw gain is what counts. (This is rare for VHF or UHF but does occur in some neighborhoods.) 2. To determine which of two antennas has a narrower beam on a given channel, just compare their gains at that channel. But in this case you use the raw gain, not the net gain. Raw gain is also called directivity. 3. There are cable-matching methods that make the net gain as good as the raw gain for any channel. But while these methods make some channels better, they make other channels worse, and there is seldom an overall improvement. There is presently no hardware available that lets consumers improve the match, except for some indoor antennas. 4. The program that predicts net gain is not very accurate. Net gain is affected by minor details in the way the cable attaches to the antenna. The raw gains are very accurate. Note that this website is probably alone in using the term “raw gain”. Other references simply call it the gain.

Net gain for some common VHF antennas

A Rabbit ears – 40” 45°

B Winegard YA-1713 Wideband Yagi for VHF 7-13

C Winegard YA-1026 Wideband Yagi for VHF 2-6

D Wade single channel Yagis (discontinued)

L Radio Shack VU-90XR VHF/UHF combo (discontinued)

M Radio Shack VU-120XR VHF/UHF combo (discontinued)

N Radio Shack VU-190XR VHF/UHF combo (discontinued)

AA Channel Master 4228

BB Channel Master 3671B VHF/UHF combo

CC Channel Master 2020

DD Channel Master 3018

EE AntennaCraft HBU44 Combo

FF Winegard HD-7698P Combo

If all the elements are parallel (as in a straight-type LPDA) then there will be nulls at +90° and –90° that might be useful for eliminating interfering signals.

Getting the most out of rabbit ears

Using a UHF antenna for VHF

Some UHF antennas are advertised as working for VHF also. As the following net gain graph shows, there is not much truth in that. For channels 7-13, the MegaWave and the Winegard PR-8800 perform about as well as rabbit ears. The Square Shooter is terrible for all VHF channels. All of these antennas are useless for channels 2-6.

The surprise here is the Channel Master 4228, which has a lot of gain for VHF-high, especially channels 9-13. What makes it different is the screen that is continuous across all 8 dipoles. Other 8-bays, like the 8800 and the DB-8, have a reflector that is not continuous across the right and left halves, and thus they have no useful gain for VHF. Channel Master is preparing a new version of the 4228 that will likely be even better for VHF-high.

Related topics

Fringe area reception

Indoor antennas

Stores and websites supplying antenna equipment

This page is part of “An HDTV Primer”, which starts at www.hdtvprimer.com