At work, I park on the top of a huge multi-story steel-frame carpark. I often wondered about using it as a ground for a HF vertical (yes, I’m that much of a nerd). I hatched a plan to give it a try!

Using a 80m HF mobile whip (borrowed from Rob M0VFC) fixed to a large triple-magmount base on the roof of my car, I was able to connect a ground strap using some wire to the car body, and trim the HF whip in to resonance with my EU1KY Antenna Analyser (which is awesome!). The plan was to connect to the ground strap to the carpark frame when at work.

In previous projects, I had made a WSPR beacon in a small project box with an OLED display on the front. The beacon takes a GPS antenna on SMA and outputs WSPR transmissions on frequency for direct connection to a low-pass filter and antenna.

Over the course of a day, I left the WSPR MEPT transmitting from the car, parked on my driveway, and achieved some impressive distances considering how inefficient these antennas are. The transmitter was set to a power of 1W, and I wasn’t expecting great results considering the antenna compromise. The results were not bad for something less than 3 metres long on the vehicle roof!

The transmitter was powered from a 12V/12Ah sealed lead acid battery with a low-voltage cut-off relay.

A table of spots, sorted by distance can be found below:

Timestamp	MHz	SNR	Grid	Reporter	RGrid	km	az	# Spots
2019-02-07 23:48	3.570109	-27	JO02	K9AN	EN50wc	6536	297	2
2019-02-08 04:14	3.570109	-28	JO02	W8AC	EN91jm	6004	294	5
2019-02-08 05:52	3.570108	-22	JO02	KD2OM	FN12gx	5664	293	29
2019-02-08 06:46	3.570109	-26	JO02	N2NOM	FN22bg	5615	291	3
2019-02-08 04:42	3.570113	-26	JO02	N2HQI	FN13sa	5598	292	24
2019-02-08 06:22	3.570110	-25	JO02	KK1D	FN31vi	5445	288	6
2019-02-08 04:02	3.570109	-25	JO02	WA9WTK	FN42fk	5327	288	2
2019-02-08 04:02	3.570106	-26	JO02	EA8DBU	IL18oe	3073	215	6
2019-02-08 05:52	3.570109	-20	JO02	EA8BFK	IL38bo	2923	211	64
2019-02-08 03:32	3.570110	-25	JO02	OH8GKP	KP24rt	1949	36	42
2019-02-08 05:52	3.570109	-26	JO02	LY2BGP	KO24ao	1536	72	26
2019-02-08 04:02	3.570109	-24	JO02	IZ6BYY	JN62wv	1435	133	42
2019-02-07 23:16	3.570111	-22	JO02	9A3ZI	JN86fj	1305	115	10
2019-02-08 17:22	3.570112	-20	JO02	OE6PJD	JN77uc	1213	114	10
2019-02-08 03:54	3.570110	-17	JO02	OE3GAS	JN88bn	1155	106	7
2019-02-07 20:22	3.570113	-13	JO02	F5OWL	JN33cc	1113	157	3
2019-02-08 03:26	3.570111	-25	JO02	IW2DMO	JN45uj	1013	138	44

On the way to Islay for the Camb Hams DXpedition, we set up an Icom IC7610 on the dashboard of Flossie.