RVLA = RV L Antenna
My Requirements for a good RV Antenna:
- 80-10 meter coverage
- Reasonable efficiency on 80, better on 40 and up
- NVIS and DX capabilities
- Portable
- Easy to put up by one person
- Packs into a small space
- Easy to change frequency
- Fits in an RV Campsite
- Fits in the RV storage lockers
- Supported by the RV
- Minimum coupling to RV systems
- Minimize RF exposure to people
- Avoid trip hazards
In the process of my search I looked at a lot of alternatives and decided to look at "L" Antennas. This page is about the RV L Antenna that I constructed and tested at Quartzsite 2006 and 2007.
(I really prefer to launch an
FT98 Dipole into the trees with a
Pneumatic Antenna Launcher∞, but when that option is not available, this is a good choice).
Configuration
- Center fed "L"
- 35.5 foot vertical element, tip at 45 feet
- 35.5 foot horizontal element, 9.5 feet above ground
- 4 feet twisted together as feedline to tuner
- RV about 30 feet long, so front pole angles out from tongue/bumper to hold horizontal wire
- 48 foot tall vertical pole near rear corner of RV, on ground but held vertical by RV (I secure this in the rear outer corner of the slideout to keep it away from the RV as much as possible
Components
- DK9SQ 33 foot pole
- DK9SQ Pole Extensions, 4 each (approx 12 feet additional)
- SD20 pole to support end of horizontal section
- #20 silver plated teflon insulated wire, 40 ft each of two pieces
- Wide range remote tuner (eg AH-4, SG-239)
- bungees / ropes / fittings to attach pole to RV
- 5 gallon plastic bucket base
- rag or foam to stuff inside base
- gaffer's tape or 3m blue masking tape to keep sections from collapsing
- front pole mount on RV (or 3 guys and stakes for ground mount)
Calculations
- feedline 4 ft 450 ohm line (don't know how to do the twisted pair, this feedline could be used instead)
- medium high accuracy ground 0.005, 13
- 100 watts
80 Meter Tuner Version (redo these numbers for the longer length, these are for 32ft per side)
- 3550 khz
- 10.6 - j 1230
- 3.8kv 3.1a
- -0.7 dbi at 25 degrees (NVIS is -2 to -9 dB)
- line loss 0.12 dB
- lowpass L tuner 1600 pf 34.8 uH, 63W, loss 4.4 dB
- total loss 4.5dB, power to antenna 36W
80 Meter Coil Version
- Impedance = 11.7 ohms
- Coil (Q 300)
- 35.7 uH
- Total load power = 26 watts (100W source)
- Total load loss = 1.3 dB
Conclusions
This antenna has a signal in just about every direction, especially on 40m. It doesn't have much gain, but it has only one depression in the pattern. It has both NVIS and DX potential, though it is not optimized for either. Matching it on 80 meters is a bit of a challenge, but it is a lot more efficient than a mobile antenna on this band (and the AH-4 has no trouble).
Testing
Quartzsite 2007. AH-4 / FT897 /
BetterRF adapter / 49AH AGM. Loads well on 75, 40, 20. Signal reports on 75m were good. No RFI problems from/to trailer so far. Would like to incorporate balun, perhaps 1:1 at tuner output. Build something designed for this app.
, WB6ZQZ
CategoryHamRadio CategoryRV
There are no comments on this page. [Add comment]