TIDA029A Application note

TIDA029A july 2019 – june 2023 CC2640R2F-Q1 , CC2642R , CC2642R-Q1

4.2.2 PCB + RF Absorbing Material + Tin-Plated Copper Foil Compensated AoA

This hardware setup’s initial tests showed fairly linear results. Therefore, with compensation, AoA values are fairly accurate (depending on the frequency) from ±80°. Table 4-2 shows the compensation values used for each frequency.

Table 4-2 PCB + RF Absorbing Material + Tin-Plated Copper Foil AoA Compensation Values

Frequency (MHz)	Channel	Gain	Offset
2402	37	2.17	–3.27
2404	0	2.17	–3.34
2406	1	2.17	–3.48
2408	2	2.17	–3.54
2410	3	2.22	–3.82
2412	4	2.22	–3.54
2414	5	2.22	–4.1
2416	6	2.22	–4.1
2418	7	2.22	–4.02
2420	8	2.22	–4.16
2422	9	2.17	–4.37
2424	10	2.17	–4.44
2426	38	2.17	–4.5
2428	11	2.17	–4.22
2430	12	2.17	–5.06
2432	13	2.17	–4.56
2434	14	2.17	–4.98
2436	15	2.17	–4.2
2438	16	2.17	–4.27
2440	17	2.13	–4.62
2442	18	2.13	–4.61
2444	19	2.17	–4.12
2446	20	2.17	–4.4
2448	21	2.17	–4.39
2450	22	2.17	–4.04
2452	23	2.17	–4.46
2454	24	2.17	–4.17
2456	25	2.17	–4.03
2458	26	2.17	–3.96
2460	27	2.17	–3.75
2462	28	2.17	–3.74
2464	29	2.17	–3.88
2466	30	2.13	–3.6
2468	31	2.13	–3.73
2470	32	2.13	–3.52
2472	33	2.13	–3.52
2474	34	2.13	–3.52
2476	35	2.08	–3.38
2478	36	2.04	–3.24
2480	39	2.04	–3.03

Figure 4-18 shows the uncompensated AoA error vs Phi and Figure 4-19 shows the compensated AoA error vs Phi.

Figure 4-18 PCB + RF Absorbing Material + Tin-Plated Copper Foil Uncompensated AoA Error

Figure 4-19 PCB + RF Absorbing Material + Tin-Plated Copper Foil Compensated AoA Error

Compensation greatly reduces the AoA error and shows less than 10° of error over most frequencies from –80° to 75°. Figure 4-20 and Figure 4-21 show how the AoA data has been adjusted to be closer to the desired result.

Figure 4-20 PCB + RF Absorbing Material + Tin-Plated Copper Foil Uncompensated AoA Results Over all Bluetooth Low Energy Channels

Figure 4-21 PCB + RF Absorbing Material + Tin-Plated Copper Foil Compensated AoA Results Over all Bluetooth Low Energy Channels