A series of antenna tests were conducted on April 14, 2016.
Objective: Compare performance of selected UHF antennas while receiving DFW TV channels
Antennas:
1. Antennas Direct 91xg
2. Solid Signal HDB91x
3. Channel Master CM-4228 (old version)
4. Antennas direct DB8 (non-e version)
5. Terk HDTVi (as reference)
Images of antennas at test location in a following post.
Test Location:
Garland, TX, ~30 miles line-of-sight to 27 DFW stations, located within +/-3 degrees azimuth.
Test location TVfool info posted earlier:
Compare Preamplifiers - Test Procedure & Configuration
Test Equipment:
1. Sencore SLM1456 – Signal Level and MER measurements
(Scans channels one-by-one, dwells a few seconds per channel to lock and obtain a signal average, total scan time for 27 channels ~6-7 minutes)
2. DG8SAQ Vector Network analyzer -VNWA
(Measure scattering parameter S11 (complex input impedance->return loss/SWR)
3. Belden Coaxial Cable 1694A (40 feet)
4. Ferrite Cores at Coax to balun/antenna connection (Qty=4)
5. Balun for CM4228 (homebrew, hand-wound ferrite core, measured loss <1 dB)
6. Push-Up Telescopic Mast, 25+ ft.
Test Procedure
1. Calibrate VNWA, with the 40’coax cable (refers measurements to antenna/balun connection).
Starting with Terk HDTVi antenna:
2. Mount antenna w/coax and ferrites to mast, raise center of antenna to 25 feet
3. Align antenna for peak signal on Channel 29 (~central angle to DFW stations)
4. With 1456 scan all DFW UHF stations for signal strength and MER (record times)
(repeat scan, while in this configuration)
5. Take at least 2 Photos
6. Turn antenna ~90 degrees, disconnect coax from 1456, connect to VNWA
7. Measure S11 (input impedance, SWR/Return Loss) for the band
8. Lower Mast remove antenna
9. For each antenna repeat steps 2 through 8, finishing with a repeat of HDTVi antenna.
The test location and setup was similar to that described in previous posts:
Televes DAT-75 vs. Antennas Direct 91XG
UHF Signal Strength vs Antenna Height (AGL)
Compare Preamplifiers - Test Procedure & Configuration
Compared to previous tests, some differences in equipment, this test:
- No attenuator was used,
- Sencore SLM1456 instead of SLM1456CM
- Others, VNWA, etc.
Credit:
Forum member re_nelson provided much appreciated assistance throughout test planning, test, and follow-up.
RE_nelson also:
- Provided most of the antennas
- Provided the Sencore SLM1456
- Aligned antenna, operated the SLM1456, performed scans, & collected data.
Image below: RE_Nelson at the antenna test station with his Sencore SLM1456.
The antenna mast is at far left behind the ladder and porch post. To aim the antenna, re_nelson observes SLM1456 and hand rotates antenna mast to maximize the signal strength indication.
(To be continued)
.