DTV antennas don't need to cost a lot of money - WALB.com, Albany News, Weather, Sports

DTV antennas don't need to cost a lot of money

Good DTV antennas don't need to cost a lot of money.  They all performed OK in UHF, but generally performed more poorly in VHF. However, most of the antenna's high (Ch 7 to 12) VHF performance was far better than low (Channels 2 to 6) performance.

The Philips MANT940 18 bb active (has an amplifier) and RCA ANT 585 antenna seemed to be the big winners with at 18  to 21 db gain with fairly flat performance even in the VHF range.

The cost on the Internet is under $25 to $35. Philips or the RCA . Neither look physically that bad and the Philips can be mounted indoors or out of doors.

  • Consumer Indoor Antenna Test Results Reported at the
    NAB Broadcast Engineering Conference

On Monday, April 14, during the "DTV Reception Issues" session which was part of the NAB Broadcast Engineering Conference (BEC), Dennis Wallace of Meintel, Sgrignoli, & Wallace gave a presentation describing the testing that they performed on consumer indoor antennas. One objective of the testing was to develop indoor "planning factors" based on the measured capabilities of the products currently in the marketplace. The facilities at Electronics Research, Inc. (ERI) were used for the tests.

As background, the presentation noted that indoor antennas will be important for consumers in the DTV transition. The tests were to determine the types and numbers of indoor antennas and to assess their performance specifications versus measured performance and then based on this data, suggest the antenna assumptions that might be used for indoor reception/propagation models.

Their research (in 2007) indicated over 107 available models:

  • 8 VHF Only Models
  • 10 UHF Only Models
  • 89 VHF/UHF Models
  • 64 Antennas with no electronic components (passive)
  • 43 Antennas had pre-amplifiers (active)
  • No "Smart" Antennas were found (it was reported that some are in development to use the CEA 909 interface).

The investigation revealed that there was very little published performance data on the antennas; rather they found lots of marketing hyperbole about "Digital" or "HDTV" Antennas; "Low Noise", "High Gain" and such. Further, there was little measured data available. The presentation showed each antenna with the available published data.

Measurement of a selected sub-set of these antennas was undertaken using ERI's Anechoic Chamber. Ten antennas were selected, a mix of five active antennas and five passive antennas. The measurements made included:

  • Gain of Antenna Relative to Dipole
  • Azimuth Pattern
  • Elevation Pattern
  • Polarization Isolation
  • Output Return Loss
  • Active Antenna Gain/Loss
  • Active Antenna Noise Figure

The presentation included the measured patterns for each antenna (not shown here) and summary tabular data, some of which is shown below.

The measured passive antenna gains (dBd) for selected channels are shown in the following table.

Antenna

Claimed Bands

Ch. 7

Ch. 14

Ch. 33

Ch. 51

ANT 115
RCA

All

-5.2

-2.7

-6.2

-0.8

Silver Sensor
Philips

UHF

-25

-3.1

-2.4

-3.0

SS 1000
Winegar

Hi-VHF,
UHF

-20.4

2.5

6.0

2.7

DB-2
Antennas Direct

UHF

-14.1

6.4

7.3

5.7

303F
Terrestrial Digital

UHF

-18.2

-1.4

-1.3

4.7

The measured active antenna gains (dBd) for selected channels are shown in the following table.

Antenna

Claimed Bands

Ch. 7

Ch. 14

Ch. 33

Ch. 51

ANT 585
RCA

All

13.4

11.7

21.0

15.6

MANT 940
Philips

UHF

7.2

16.4

18.1

20.5

SS2000
Winegard

Hi-VHF, UHF

-10.5

12.3

15.8

14.6

TV25
Terk

All

24.3

12.4

13.7

12.6

SS3000/HDTVIp
Winegard/Terk

All

-3.8

13.3

15.4

13.6

Each of the five active indoor antennas was evaluated for preamplifier performance. Selected results are shown in the following table.

Antenna

Gain dB

Noise Figure
dB

ANT 585

21.5

3.1

MANT 940

20.9

3.6

SS2000

8.8

4.6

TV 25

21.5

3.9

SS3000

8.6

4.7

Mr. Wallace offered the following conclusions:

Some antennas have very well behaved directional UHF patterns as exemplified by the Silver Sensor, SS1000, SS2000, DB2, and SS3000/HDTVIp. They typically had good Front/Back ratio (>10dB) and polarization Isolation 6-10dB. The Sharpshooter behaved well at Hi-VHF frequencies as well.

Hi-VHF Performance for the UHF Only Antennas was generally poor and variable. For example, the Silver Sensor Hi-VHF reception was 90 degrees from "front" of antenna. Other antennas were "Quasi-Omni-directional" (ANT115, ANT585, MANT940, TV25, 303F) with broad patterns for azimuth and poorer polarization isolation. Some of these had greater gain in vertical orientation.

Active antennas generally had better return loss and would provide impedance mismatch isolation to the receiver.

Generalizing from the results these antennas suggest are appropriate, the following preliminary planning factors were among those suggested.

Parameter

Hi-VHF
Passive

UHF
Passive

Hi-VHF
Active

UHF
Active

Net Gain

5 dBd

+3 dBd

+11 dBd

+14 dBd

Pre Amp Gain

NA

NA

+20 dB

+17 dB

Pre Amp NF

NA

NA

3.5

4.0

Return Loss

3 dB

6 dB

10 dB

10 dB